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• How can I limit the cache used by copying so there is still memory available for other cache?

  - by Peter

  Basic situation: I am copying some NTFS disks in openSuSE. Each one is 2TB. When I do this, the system runs slow. My guesses: I believe it is likely due to caching. Linux decides to discard useful cache (eg. kde4 bloat, virtual machine disks, LibreOffice binaries, Thunderbird binaries, etc.) and instead fill all available memory (24 GB total) with stuff from the copying disks, which will be read only once, then written and never used again. So then any time I use these apps (or kde4), the disk needs to be read again, and reading the bloat off the disk again makes things freeze/hiccup. Due to the cache being gone and the fact that these bloated applications need lots of cache, this makes the system horribly slow. Since it is USB,the disk and disk controller are not the bottleneck, so using ionice does not make it faster. I believe it is the cache rather than just the motherboard going too slow, because if I stop everything copying, it still runs choppy for a while until it recaches everything. And if I restart the copying, it takes a minute before it is choppy again. But also, I can limit it to around 40 MB/s, and it runs faster again (not because it has the right things cached, but because the motherboard busses have lots of extra bandwidth for the system disks). I can fully accept a performance loss from my motherboard's IO capability being completely consumed (which is 100% used, meaning 0% wasted power which makes me happy), but I can't accept that this caching mechanism performs so terribly in this specific use case. # free total used free shared buffers cached Mem: 24731556 24531876 199680 0 8834056 12998916 -/+ buffers/cache: 2698904 22032652 Swap: 4194300 24764 4169536 I also tried the same thing on Ubuntu, which causes a total system hang instead. ;) And to clarify, I am not asking how to leave memory free for the "system", but for "cache". I know that cache memory is automatically given back to the system when needed, but my problem is that it is not reserved for caching of specific things. Question: Is there some way to tell these copy operations to limit memory usage so some important things remain cached, and therefore any slowdowns are a result of normal disk usage and not rereading the same commonly used files? For example, is there a setting of max memory per process/user/file system allowed to be used as cache/buffers?

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• C#/.NET Little Wonders: Interlocked Read() and Exchange()

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Last time we discussed the Interlocked class and its Add(), Increment(), and Decrement() methods which are all useful for updating a value atomically by adding (or subtracting).  However, this begs the question of how do we set and read those values atomically as well? Read() – Read a value atomically Let’s begin by examining the following code: 1: public class Incrementor 2: { 3: private long _value = 0; 4:  5: public long Value { get { return _value; } } 6:  7: public void Increment() 8: { 9: Interlocked.Increment(ref _value); 10: } 11: } 12:  It uses an interlocked increment, as we discuss in my previous post (here), so we know that the increment will be thread-safe.  But, to realize what’s potentially wrong we have to know a bit about how atomic reads are in 32 bit and 64 bit .NET environments. When you are dealing with an item smaller or equal to the system word size (such as an int on a 32 bit system or a long on a 64 bit system) then the read is generally atomic, because it can grab all of the bits needed at once.  However, when dealing with something larger than the system word size (reading a long on a 32 bit system for example), it cannot grab the whole value at once, which can lead to some problems since this read isn’t atomic. For example, this means that on a 32 bit system we may read one half of the long before another thread increments the value, and the other half of it after the increment.  To protect us from reading an invalid value in this manner, we can do an Interlocked.Read() to force the read to be atomic (of course, you’d want to make sure any writes or increments are atomic also): 1: public class Incrementor 2: { 3: private long _value = 0; 4:  5: public long Value 6: { 7: get { return Interlocked.Read(ref _value); } 8: } 9:  10: public void Increment() 11: { 12: Interlocked.Increment(ref _value); 13: } 14: } Now we are guaranteed that we will read the 64 bit value atomically on a 32 bit system, thus ensuring our thread safety (assuming all other reads, writes, increments, etc. are likewise protected).  Note that as stated before, and according to the MSDN (here), it isn’t strictly necessary to use Interlocked.Read() for reading 64 bit values on 64 bit systems, but for those still working in 32 bit environments, it comes in handy when dealing with long atomically. Exchange() – Exchanges two values atomically Exchange() lets us store a new value in the given location (the ref parameter) and return the old value as a result. So just as Read() allows us to read atomically, one use of Exchange() is to write values atomically.  For example, if we wanted to add a Reset() method to our Incrementor, we could do something like this: 1: public void Reset() 2: { 3: _value = 0; 4: } But the assignment wouldn’t be atomic on 32 bit systems, since the word size is 32 bits and the variable is a long (64 bits).  Thus our assignment could have only set half the value when a threaded read or increment happens, which would put us in a bad state. So instead, we could write Reset() like this: 1: public void Reset() 2: { 3: Interlocked.Exchange(ref _value, 0); 4: } And we’d be safe again on a 32 bit system. But this isn’t the only reason Exchange() is valuable.  The key comes in realizing that Exchange() doesn’t just set a new value, it returns the old as well in an atomic step.  Hence the name “exchange”: you are swapping the value to set with the stored value. So why would we want to do this?  Well, anytime you want to set a value and take action based on the previous value.  An example of this might be a scheme where you have several tasks, and during every so often, each of the tasks may nominate themselves to do some administrative chore.  Perhaps you don’t want to make this thread dedicated for whatever reason, but want to be robust enough to let any of the threads that isn’t currently occupied nominate itself for the job.  An easy and lightweight way to do this would be to have a long representing whether someone has acquired the “election” or not.  So a 0 would indicate no one has been elected and 1 would indicate someone has been elected. We could then base our nomination strategy as follows: every so often, a thread will attempt an Interlocked.Exchange() on the long and with a value of 1.  The first thread to do so will set it to a 1 and return back the old value of 0.  We can use this to show that they were the first to nominate and be chosen are thus “in charge”.  Anyone who nominates after that will attempt the same Exchange() but will get back a value of 1, which indicates that someone already had set it to a 1 before them, thus they are not elected. Then, the only other step we need take is to remember to release the election flag once the elected thread accomplishes its task, which we’d do by setting the value back to 0.  In this way, the next thread to nominate with Exchange() will get back the 0 letting them know they are the new elected nominee. Such code might look like this: 1: public class Nominator 2: { 3: private long _nomination = 0; 4: public bool Elect() 5: { 6: return Interlocked.Exchange(ref _nomination, 1) == 0; 7: } 8: public bool Release() 9: { 10: return Interlocked.Exchange(ref _nomination, 0) == 1; 11: } 12: } There’s many ways to do this, of course, but you get the idea.  Running 5 threads doing some “sleep” work might look like this: 1: var nominator = new Nominator(); 2: var random = new Random(); 3: Parallel.For(0, 5, i => 4: { 5:  6: for (int j = 0; j < _iterations; ++j) 7: { 8: if (nominator.Elect()) 9: { 10: // elected 11: Console.WriteLine("Elected nominee " + i); 12: Thread.Sleep(random.Next(100, 5000)); 13: nominator.Release(); 14: } 15: else 16: { 17: // not elected 18: Console.WriteLine("Did not elect nominee " + i); 19: } 20: // sleep before check again 21: Thread.Sleep(1000); 22: } 23: }); And would spit out results like: 1: Elected nominee 0 2: Did not elect nominee 2 3: Did not elect nominee 1 4: Did not elect nominee 4 5: Did not elect nominee 3 6: Did not elect nominee 3 7: Did not elect nominee 1 8: Did not elect nominee 2 9: Did not elect nominee 4 10: Elected nominee 3 11: Did not elect nominee 2 12: Did not elect nominee 1 13: Did not elect nominee 4 14: Elected nominee 0 15: Did not elect nominee 2 16: Did not elect nominee 4 17: ... Another nice thing about the Interlocked.Exchange() is it can be used to thread-safely set pretty much anything 64 bits or less in size including references, pointers (in unsafe mode), floats, doubles, etc.  Summary So, now we’ve seen two more things we can do with Interlocked: reading and exchanging a value atomically.  Read() and Exchange() are especially valuable for reading/writing 64 bit values atomically in a 32 bit system.  Exchange() has value even beyond simply atomic writes by using the Exchange() to your advantage, since it reads and set the value atomically, which allows you to do lightweight nomination systems. There’s still a few more goodies in the Interlocked class which we’ll explore next time! Technorati Tags: C#,CSharp,.NET,Little Wonders,Interlocked

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• "domain crashed" when creating new Xen instance

  - by user47650

  I have downloaded a Xen virtual machine image from the appscale project, and I am trying to start it up. However once I run the command; xm create -c -f xen.conf The instance immediately crashes and provides no console output. however it produces logs that I have posted below. but this is the error; [2011-03-01 12:34:03 xend.XendDomainInfo 3580] WARNING (XendDomainInfo:1178) Domain has crashed: name=appscale-1.4b id=10. I have managed to mount the root.img file locally and verify that it is actually an ext3 file system. I am running Xen 3.0.3 that is a stock RPM from the CentOS 5 repos; # rpm -qa | grep -i xen xen-libs-3.0.3-105.el5_5.5 xen-3.0.3-105.el5_5.5 xen-libs-3.0.3-105.el5_5.5 kernel-xen-2.6.18-194.32.1.el5 any suggestions on how to proceed with troubleshooting? (i am a newbie to Xen) so far I have enabled console logging, but the log file is empty. ==> domain-builder-ng.log <== xc_dom_allocate: cmdline=" ip=:1.2.3.4::::eth0:dhcp root=/dev/sda1 ro xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console", features="" xc_dom_kernel_file: filename="/boot/vmlinuz-2.6.27-7-server" xc_dom_malloc_filemap : 2284 kB xc_dom_ramdisk_file: filename="/boot/initrd.img-2.6.27-7-server" xc_dom_malloc_filemap : 9005 kB xc_dom_boot_xen_init: ver 3.1, caps xen-3.0-x86_64 xen-3.0-x86_32p xc_dom_parse_image: called xc_dom_find_loader: trying ELF-generic loader ... failed xc_dom_find_loader: trying Linux bzImage loader ... xc_dom_malloc : 9875 kB xc_dom_do_gunzip: unzip ok, 0x234bb2 -> 0x9a4de0 OK elf_parse_binary: phdr: paddr=0x200000 memsz=0x447000 elf_parse_binary: phdr: paddr=0x647000 memsz=0xab888 elf_parse_binary: phdr: paddr=0x6f3000 memsz=0x908 elf_parse_binary: phdr: paddr=0x6f4000 memsz=0x1c2f9c elf_parse_binary: memory: 0x200000 -> 0x8b6f9c elf_xen_parse_note: GUEST_OS = "linux" elf_xen_parse_note: GUEST_VERSION = "2.6" elf_xen_parse_note: XEN_VERSION = "xen-3.0" elf_xen_parse_note: VIRT_BASE = 0xffffffff80000000 elf_xen_parse_note: ENTRY = 0xffffffff8071e200 elf_xen_parse_note: HYPERCALL_PAGE = 0xffffffff80209000 elf_xen_parse_note: FEATURES = "!writable_page_tables|pae_pgdir_above_4gb" elf_xen_parse_note: PAE_MODE = "yes" elf_xen_parse_note: LOADER = "generic" elf_xen_parse_note: unknown xen elf note (0xd) elf_xen_parse_note: SUSPEND_CANCEL = 0x1 elf_xen_parse_note: HV_START_LOW = 0xffff800000000000 elf_xen_parse_note: PADDR_OFFSET = 0x0 elf_xen_addr_calc_check: addresses: virt_base = 0xffffffff80000000 elf_paddr_offset = 0x0 virt_offset = 0xffffffff80000000 virt_kstart = 0xffffffff80200000 virt_kend = 0xffffffff808b6f9c virt_entry = 0xffffffff8071e200 xc_dom_parse_elf_kernel: xen-3.0-x86_64: 0xffffffff80200000 -> 0xffffffff808b6f9c xc_dom_mem_init: mem 1024 MB, pages 0x40000 pages, 4k each xc_dom_mem_init: 0x40000 pages xc_dom_boot_mem_init: called x86_compat: guest xen-3.0-x86_64, address size 64 xc_dom_malloc : 2048 kB ==> xend.log <== [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:01 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] INFO (XendDomainInfo:957) Dev 0 still active, looping... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2114) UUID Created: True [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2115) Devices to release: [], domid = 9 [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2127) Releasing PVFB backend devices ... [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:207) XendDomainInfo.create(['domain', ['domid', 9], ['uuid', 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0'], ['vcpus', 1], ['vcpu_avail', 1], ['cpu_cap', 0], ['cpu_weight', 256], ['memory', 1024], ['shadow_memory', 0], ['maxmem', 1024], ['features', ''], ['name', 'appscale-1.4b'], ['on_poweroff', 'destroy'], ['on_reboot', 'restart'], ['on_crash', 'restart'], ['image', ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']]], ['cpus', []], ['device', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]], ['device', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']]], ['state', '----c-'], ['shutdown_reason', 'crash'], ['cpu_time', 0.000339131], ['online_vcpus', 1], ['up_time', '0.952092885971'], ['start_time', '1299011639.92'], ['store_mfn', 1169289], ['console_mfn', 1169288]]) [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:329) parseConfig: config is ['domain', ['domid', 9], ['uuid', 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0'], ['vcpus', 1], ['vcpu_avail', 1], ['cpu_cap', 0], ['cpu_weight', 256], ['memory', 1024], ['shadow_memory', 0], ['maxmem', 1024], ['features', ''], ['name', 'appscale-1.4b'], ['on_poweroff', 'destroy'], ['on_reboot', 'restart'], ['on_crash', 'restart'], ['image', ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']]], ['cpus', []], ['device', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]], ['device', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']]], ['state', '----c-'], ['shutdown_reason', 'crash'], ['cpu_time', 0.000339131], ['online_vcpus', 1], ['up_time', '0.952092885971'], ['start_time', '1299011639.92'], ['store_mfn', 1169289], ['console_mfn', 1169288]] [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:446) parseConfig: result is {'features': '', 'image': ['linux', ['kernel', '/boot/vmlinuz-2.6.27-7-server'], ['ramdisk', '/boot/initrd.img-2.6.27-7-server'], ['ip', ':1.2.3.4::::eth0:dhcp'], ['root', '/dev/sda1 ro'], ['args', 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console']], 'cpus': [], 'vcpu_avail': 1, 'backend': [], 'uuid': 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'on_reboot': 'restart', 'cpu_weight': 256.0, 'memory': 1024, 'cpu_cap': 0, 'localtime': None, 'timer_mode': None, 'start_time': 1299011639.9200001, 'on_poweroff': 'destroy', 'on_crash': 'restart', 'device': [('vif', ['vif', ['backend', 0], ['script', 'vif-bridge'], ['mac', '00:16:3B:72:10:E4']]), ('vbd', ['vbd', ['backend', 0], ['dev', 'sda1:disk'], ['uname', 'file:/local/xen/domains/appscale1.4/root.img'], ['mode', 'w']])], 'bootloader': None, 'maxmem': 1024, 'shadow_memory': 0, 'name': 'appscale-1.4b', 'bootloader_args': None, 'vcpus': 1, 'cpu': None} [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1784) XendDomainInfo.construct: None [2011-03-01 12:34:02 xend 3580] DEBUG (balloon:145) Balloon: 3034420 KiB free; need 4096; done. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1953) XendDomainInfo.initDomain: 10 256.0 [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1994) _initDomain:shadow_memory=0x0, maxmem=0x400, memory=0x400. [2011-03-01 12:34:02 xend 3580] DEBUG (balloon:145) Balloon: 3034412 KiB free; need 1048576; done. [2011-03-01 12:34:02 xend 3580] INFO (image:139) buildDomain os=linux dom=10 vcpus=1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:208) domid = 10 [2011-03-01 12:34:02 xend 3580] DEBUG (image:209) memsize = 1024 [2011-03-01 12:34:02 xend 3580] DEBUG (image:210) image = /boot/vmlinuz-2.6.27-7-server [2011-03-01 12:34:02 xend 3580] DEBUG (image:211) store_evtchn = 1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:212) console_evtchn = 2 [2011-03-01 12:34:02 xend 3580] DEBUG (image:213) cmdline = ip=:1.2.3.4::::eth0:dhcp root=/dev/sda1 ro xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console [2011-03-01 12:34:02 xend 3580] DEBUG (image:214) ramdisk = /boot/initrd.img-2.6.27-7-server [2011-03-01 12:34:02 xend 3580] DEBUG (image:215) vcpus = 1 [2011-03-01 12:34:02 xend 3580] DEBUG (image:216) features = ==> domain-builder-ng.log <== xc_dom_build_image: called xc_dom_alloc_segment: kernel : 0xffffffff80200000 -> 0xffffffff808b7000 (pfn 0x200 + 0x6b7 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x200+0x6b7 at 0x2aaaab5f6000 elf_load_binary: phdr 0 at 0x0x2aaaab5f6000 -> 0x0x2aaaaba3d000 elf_load_binary: phdr 1 at 0x0x2aaaaba3d000 -> 0x0x2aaaabae8888 elf_load_binary: phdr 2 at 0x0x2aaaabae9000 -> 0x0x2aaaabae9908 elf_load_binary: phdr 3 at 0x0x2aaaabaea000 -> 0x0x2aaaabb9a004 xc_dom_alloc_segment: ramdisk : 0xffffffff808b7000 -> 0xffffffff82382000 (pfn 0x8b7 + 0x1acb pages) xc_dom_malloc : 160 kB xc_dom_pfn_to_ptr: domU mapping: pfn 0x8b7+0x1acb at 0x2aaab0000000 xc_dom_do_gunzip: unzip ok, 0x8cb5e7 -> 0x1aca210 xc_dom_alloc_segment: phys2mach : 0xffffffff82382000 -> 0xffffffff82582000 (pfn 0x2382 + 0x200 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x2382+0x200 at 0x2aaab1acb000 xc_dom_alloc_page : start info : 0xffffffff82582000 (pfn 0x2582) xc_dom_alloc_page : xenstore : 0xffffffff82583000 (pfn 0x2583) xc_dom_alloc_page : console : 0xffffffff82584000 (pfn 0x2584) nr_page_tables: 0x0000ffffffffffff/48: 0xffff000000000000 -> 0xffffffffffffffff, 1 table(s) nr_page_tables: 0x0000007fffffffff/39: 0xffffff8000000000 -> 0xffffffffffffffff, 1 table(s) nr_page_tables: 0x000000003fffffff/30: 0xffffffff80000000 -> 0xffffffffbfffffff, 1 table(s) nr_page_tables: 0x00000000001fffff/21: 0xffffffff80000000 -> 0xffffffff827fffff, 20 table(s) xc_dom_alloc_segment: page tables : 0xffffffff82585000 -> 0xffffffff8259c000 (pfn 0x2585 + 0x17 pages) xc_dom_pfn_to_ptr: domU mapping: pfn 0x2585+0x17 at 0x2aaab1ccb000 xc_dom_alloc_page : boot stack : 0xffffffff8259c000 (pfn 0x259c) xc_dom_build_image : virt_alloc_end : 0xffffffff8259d000 xc_dom_build_image : virt_pgtab_end : 0xffffffff82800000 xc_dom_boot_image: called arch_setup_bootearly: doing nothing xc_dom_compat_check: supported guest type: xen-3.0-x86_64 <= matches xc_dom_compat_check: supported guest type: xen-3.0-x86_32p xc_dom_update_guest_p2m: dst 64bit, pages 0x40000 clear_page: pfn 0x2584, mfn 0x11d788 clear_page: pfn 0x2583, mfn 0x11d789 xc_dom_pfn_to_ptr: domU mapping: pfn 0x2582+0x1 at 0x2aaab1ce2000 start_info_x86_64: called setup_hypercall_page: vaddr=0xffffffff80209000 pfn=0x209 domain builder memory footprint allocated malloc : 12139 kB anon mmap : 0 bytes mapped file mmap : 11289 kB domU mmap : 35 MB arch_setup_bootlate: shared_info: pfn 0x0, mfn 0xd6fe1 shared_info_x86_64: called vcpu_x86_64: called vcpu_x86_64: cr3: pfn 0x2585 mfn 0x11d787 launch_vm: called, ctxt=0x97b21f8 xc_dom_release: called ==> xend.log <== [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:114) DevController: writing {'mac': '00:16:3B:72:10:E4', 'handle': '0', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/vif/10/0'} to /local/domain/10/device/vif/0. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:116) DevController: writing {'domain': 'appscale-1.4b', 'handle': '0', 'script': '/etc/xen/scripts/vif-bridge', 'state': '1', 'frontend': '/local/domain/10/device/vif/0', 'mac': '00:16:3B:72:10:E4', 'online': '1', 'frontend-id': '10'} to /local/domain/0/backend/vif/10/0. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:634) Checking for duplicate for uname: /local/xen/domains/appscale1.4/root.img [file:/local/xen/domains/appscale1.4/root.img], dev: sda1:disk, mode: w [2011-03-01 12:34:02 xend 3580] DEBUG (blkif:27) exception looking up device number for sda1:disk: [Errno 2] No such file or directory: '/dev/sda1:disk' [2011-03-01 12:34:02 xend 3580] DEBUG (blkif:27) exception looking up device number for sda1: [Errno 2] No such file or directory: '/dev/sda1' [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:114) DevController: writing {'virtual-device': '2049', 'device-type': 'disk', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/vbd/10/2049'} to /local/domain/10/device/vbd/2049. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:116) DevController: writing {'domain': 'appscale-1.4b', 'frontend': '/local/domain/10/device/vbd/2049', 'format': 'raw', 'dev': 'sda1', 'state': '1', 'params': '/local/xen/domains/appscale1.4/root.img', 'mode': 'w', 'online': '1', 'frontend-id': '10', 'type': 'file'} to /local/domain/0/backend/vbd/10/2049. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:993) Storing VM details: {'shadow_memory': '0', 'uuid': 'd5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'on_reboot': 'restart', 'start_time': '1299011642.74', 'on_poweroff': 'destroy', 'name': 'appscale-1.4b', 'xend/restart_count': '0', 'vcpus': '1', 'vcpu_avail': '1', 'memory': '1024', 'on_crash': 'restart', 'image': "(linux (kernel /boot/vmlinuz-2.6.27-7-server) (ramdisk /boot/initrd.img-2.6.27-7-server) (ip :1.2.3.4::::eth0:dhcp) (root '/dev/sda1 ro') (args 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console'))", 'maxmem': '1024'} [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1028) Storing domain details: {'console/ring-ref': '1169288', 'console/port': '2', 'name': 'appscale-1.4b', 'console/limit': '1048576', 'vm': '/vm/d5f22dd4-8dc2-f51f-84e9-eea7d71ea1d0', 'domid': '10', 'cpu/0/availability': 'online', 'memory/target': '1048576', 'store/ring-ref': '1169289', 'store/port': '1'} [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:158) Waiting for devices vif. [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:164) Waiting for 0. [2011-03-01 12:34:02 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:1250) XendDomainInfo.handleShutdownWatch [2011-03-01 12:34:02 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vif/10/0/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vif/10/0/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:523) hotplugStatusCallback 1. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices usb. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vbd. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:164) Waiting for 2049. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vbd/10/2049/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:509) hotplugStatusCallback /local/domain/0/backend/vbd/10/2049/hotplug-status. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:523) hotplugStatusCallback 1. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices irq. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vkbd. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vfb. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices pci. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices ioports. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices tap. [2011-03-01 12:34:03 xend 3580] DEBUG (DevController:158) Waiting for devices vtpm. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] WARNING (XendDomainInfo:1178) Domain has crashed: name=appscale-1.4b id=10. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] ERROR (XendDomainInfo:2654) VM appscale-1.4b restarting too fast (2.275545 seconds since the last restart). Refusing to restart to avoid loops. [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2189) XendDomainInfo.destroy: domid=10 ==> xen-hotplug.log <== Nothing to flush. ==> xend.log <== [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] INFO (XendDomainInfo:2330) Dev 2049 still active, looping... [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2114) UUID Created: True [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2115) Devices to release: [], domid = 10 [2011-03-01 12:34:03 xend.XendDomainInfo 3580] DEBUG (XendDomainInfo:2127) Releasing PVFB backend devices ... And this is the xen.conf file that I am using; # cat xen.conf # Configuration file for the Xen instance AppScale, created # bn VMBuilder kernel = '/boot/vmlinuz-2.6.27-7-server' ramdisk = '/boot/initrd.img-2.6.27-7-server' memory = 1024 vcpus = 1 root = '/dev/sda1 ro' disk = [ 'file:/local/xen/domains/appscale1.4/root.img,sda1,w', ] name = 'appscale-1.4b' dhcp = 'dhcp' vif = [ 'mac=00:16:3B:72:10:E4' ] on_poweroff = 'destroy' on_reboot = 'restart' on_crash = 'restart' extra = 'xencons=tty console=tty1 console=hvc0 debugger=y debug=y sync_console'

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• Useful Command-line Commands on Windows

  - by Sung Meister

  The aim for this Wiki is to promote using a command to open up commonly used applications without having to go through many mouse clicks - thus saving time on monitoring and troubleshooting Windows machines. Answer entries need to specify Application name Commands Screenshot (Optional) Shortcut to commands && - Command Chaining %SYSTEMROOT%\System32\rcimlby.exe -LaunchRA - Remote Assistance (Windows XP) appwiz.cpl - Programs and Features (Formerly Known as "Add or Remove Programs") appwiz.cpl @,2 - Turn Windows Features On and Off (Add/Remove Windows Components pane) arp - Displays and modifies the IP-to-Physical address translation tables used by address resolution protocol (ARP) at - Schedule tasks either locally or remotely without using Scheduled Tasks bootsect.exe - Updates the master boot code for hard disk partitions to switch between BOOTMGR and NTLDR cacls - Change Access Control List (ACL) permissions on a directory, its subcontents, or files calc - Calculator chkdsk - Check/Fix the disk surface for physical errors or bad sectors cipher - Displays or alters the encryption of directories [files] on NTFS partitions cleanmgr.exe - Disk Cleanup clip - Redirects output of command line tools to the Windows clipboard cls - clear the command line screen cmd /k - Run command with command extensions enabled color - Sets the default console foreground and background colors in console command.com - Default Operating System Shell compmgmt.msc - Computer Management control.exe /name Microsoft.NetworkAndSharingCenter - Network and Sharing Center control keyboard - Keyboard Properties control mouse(or main.cpl) - Mouse Properties control sysdm.cpl,@0,3 - Advanced Tab of the System Properties dialog control userpasswords2 - Opens the classic User Accounts dialog desk.cpl - opens the display properties devmgmt.msc - Device Manager diskmgmt.msc - Disk Management diskpart - Disk management from the command line dsa.msc - Opens active directory users and computers dsquery - Finds any objects in the directory according to criteria dxdiag - DirectX Diagnostic Tool eventvwr - Windows Event Log (Event Viewer) explorer . - Open explorer with the current folder selected. explorer /e, . - Open explorer, with folder tree, with current folder selected. F7 - View command history find - Searches for a text string in a file or files findstr - Find a string in a file firewall.cpl - Opens the Windows Firewall settings fsmgmt.msc - Shared Folders fsutil - Perform tasks related to FAT and NTFS file systems ftp - Transfers files to and from a computer running an FTP server service getmac - Shows the mac address(es) of your network adapter(s) gpedit.msc - Group Policy Editor gpresult - Displays the Resultant Set of Policy (RSoP) information for a target user and computer httpcfg.exe - HTTP Configuration Utility iisreset - To restart IIS InetMgr.exe - Internet Information Services (IIS) Manager 7 InetMgr6.exe - Internet Information Services (IIS) Manager 6 intl.cpl - Regional and Language Options ipconfig - Internet protocol configuration lusrmgr.msc - Local Users and Groups Administrator msconfig - System Configuration notepad - Notepad? ;) mmsys.cpl - Sound/Recording/Playback properties mode - Configure system devices more - Displays one screen of output at a time mrt - Microsoft Windows Malicious Software Removal Tool mstsc.exe - Remote Desktop Connection nbstat - displays protocol statistics and current TCP/IP connections using NBT ncpa.cpl - Network Connections netsh - Display or modify the network configuration of a computer that is currently running netstat - Network Statistics net statistics - Check computer up time net stop - Stops a running service. net use - Connects a computer to or disconnects a computer from a shared resource, or displays information about computer connections odbcad32.exe - ODBC Data Source Administrator pathping - A traceroute that collects detailed packet loss stats perfmon - Opens Reliability and Performance Monitor ping - Determine whether a remote computer is accessible over the network powercfg.cpl - Power management control panel applet quser - Display information about user sessions on a terminal server qwinsta - See disconnected remote desktop sessions reg.exe - Console Registry Tool for Windows regedit - Registry Editor rasdial - Connects to a VPN or a dialup network robocopy - Backup/Restore/Copy large amounts of files reliably rsop.msc - Resultant Set of Policy (shows the combined effect of all group policies active on the current system/login) runas - Run specific tools and programs with different permissions than the user's current logon provides sc - Manage anything you want to do with services. schtasks - Enables an administrator to create, delete, query, change, run and end scheduled tasks on a local or remote system. secpol.msc - Local Security Settings services.msc - Services control panel set - Displays, sets, or removes cmd.exe environment variables. set DIRCMD - Preset dir parameter in cmd.exe start - Starts a separate window to run a specified program or command start. - opens the current directory in the Windows Explorer. shutdown.exe - Shutdown or Reboot a local/remote machine subst.exe - Associates a path with a drive letter, including local drives systeminfo -Displays a comprehensive information about the system taskkill - terminate tasks by process id (PID) or image name tasklist.exe - List Processes on local or a remote machine taskmgr.exe - Task Manager telephon.cpl - Telephone and Modem properties timedate.cpl - Date and Time title - Change the title of the CMD window you have open tracert - Trace route wmic - Windows Management Instrumentation Command-line winver.exe - Find Windows Version wscui.cpl - Windows Security Center wuauclt.exe - Windows Update AutoUpdate Client

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• ubuntu 10.04; kvm bridged networking not working with public ip addresses

  - by senorsmile

  I have a dedicated hosted server box with ubuntu 10.04 64 bit installed. I would like to run kvm with ubuntu 8.04 installed for some php 5.2 compatible apps(they don't work right with php 5.3, the default in ubuntu 10.04). I installed KVM as instructed at https://help.ubuntu.com/community/KVM/Installation . I installed the vm using virt-manager. I never could figure out how use virt-install or any of those automated installers. I just installed it using the disc. I set up bridged networking as per https://help.ubuntu.com/community/KVM/Networking . However, the bridged connection doesn't work. Here's my /etc/network/interfaces on the host, running ubuntu 10.04. (with specific public ip blanked) auto lo iface lo inet loopback auto eth0 iface eth0 inet manual auto br0 iface br0 inet static address xx.xx.xx.xx netmask 255.255.255.248 gateway xx.xx.xx.xa bridge_ports eth0 bridge_stp on bridge_fd 0 bridge_maxwait 10 ` Here's my /etc/network/interfaces on the guest, running ubuntu 8.04. auto lo iface lo inet loopback auto eth0 iface eth0 inet static address xx.xx.xx.xy netmask 255.255.255.248 gateway xx.xx.xx.xa The two vm's can communicate to each other. But, the guest vm can't access anyone in the real world. Here's my /etc/libvirt/qemu/store_804.xml <domain type='kvm'> <name>store_804</name> <uuid>27acfb75-4f90-a34c-9a0b-70a6927ae84c</uuid> <memory>2097152</memory> <currentMemory>2097152</currentMemory> <vcpu>2</vcpu> <os> <type arch='x86_64' machine='pc-0.12'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>restart</on_crash> <devices> <emulator>/usr/bin/kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/var/lib/libvirt/images/store_804.img'/> <target dev='hda' bus='ide'/> </disk> <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='hdc' bus='ide'/> <readonly/> </disk> <interface type='bridge'> <mac address='52:54:00:26:0b:c6'/> <source bridge='br0'/> <model type='virtio'/> </interface> <console type='pty'> <target port='0'/> </console> <console type='pty'> <target port='0'/> </console> <input type='mouse' bus='ps2'/> <graphics type='vnc' port='-1' autoport='yes'/> <sound model='es1370'/> <video> <model type='cirrus' vram='9216' heads='1'/> </video> </devices> </domain> Any idea where I've gone wrong?

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• RAID controller dropping the wrong drive

  - by bramp

  I've been having an issue with 3ware 9500S-8 RAID 10, and I have contracted their tech support, but I wanted to hear the serverfault community's recommendations. Firstly, all my data is backuped and secure, so I don't mind blowing my RAID away if I have to. But let me describe the problem I've been seeing. A month ago, disk 6 dropped out of the RAID. It is mirrored with disk 7, so I wasn't that bothered. I went to the data centre and replaced it. When I got back to the office, I noticed that disk 6 will still not in the RAID, and in fact the controller was show the name of the old drive still. A week later I went back and replace the drive again, thinking I might have swapped in a bad drive. Still the same problem. I decided to reboot the machine, to see if that would "force" the controller into seeing the new drive. It did, and a rebuild started to happen (from disk 7). Eventually both drives were showing as good. A week later, the MySQL database has flagged the database is corrupt, and is unable to repair it. I don't know what has gone wrong, but I suspected this 6-7 pair. At this point I noticed that the RAID had constantly been verifying itself, over and over. Regardless of this I began to rebuild the database, which took about 19 hours. It's a big database. Near the end of the repair, the RAID controller told me it had dropped disk 7, and that some data was most likely corrupted. I contacted LSI tech support, and they very promptly started to help me. I mentioned that drive 7 had been dropped. They suspect that drive 7 was always at fault, and drive 6 had always been good. I want to know how often a RAID controller would drop the wrong drive (in this case dropping drive 6 a month ago, instead of 7). I foolishly didn't run smartctl on the drives before I started swapping them out. I just assumed the RAID controller knew what it was talking about. I think my plan of action is to replace drive 7, rebuild the array from scratch, double check smartctl on ALL the disks, and then start restoring my data again. I would appreciate anyone's input on what the correct procedure for swapping drives is, and how often failures like this happen. If anyone would like more information then I'd be happy to provide it. thanks in advance. Oh some more information. I'm running CentOS 5.3, with two RAID arrays, a simple RAID 1 for the OS, and RAID 10 for the database. Both arrays are on different controllers. The RAID 10 is made of 10 identical ST3640323AS drives, until I swapped in a SAMSUNG HD103SJ last month.

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• What *exactly* gets screwed when I kill -9 or pull the power?

  - by Mike

  Set-Up I've been a programmer for quite some time now but I'm still a bit fuzzy on deep, internal stuff. Now. I am well aware that it's not a good idea to either: kill -9 a process (bad) spontaneously pull the power plug on a running computer or server (worse) However, sometimes you just plain have to. Sometimes a process just won't respond no matter what you do, and sometimes a computer just won't respond, no matter what you do. Let's assume a system running Apache 2, MySQL 5, PHP 5, and Python 2.6.5 through mod_wsgi. Note: I'm most interested about Mac OS X here, but an answer that pertains to any UNIX system would help me out. My Concern Each time I have to do either one of these, especially the second, I'm very worried for a period of time that something has been broken. Some file somewhere could be corrupt -- who knows which file? There are over 1,000,000 files on the computer. I'm often using OS X, so I'll run a "Verify Disk" operation through the Disk Utility. It will report no problems, but I'm still concerned about this. What if some configuration file somewhere got screwed up. Or even worse, what if a binary file somewhere is corrupt. Or a script file somewhere is corrupt now. What if some hardware is damaged? What if I don't find out about it until next month, in a critical scenario, when the corruption or damage causes a catastrophe? Or, what if valuable data is already lost? My Hope My hope is that these concerns and worries are unfounded. After all, after doing this many times before, nothing truly bad has happened yet. The worst is I've had to repair some MySQL tables, but I don't seem to have lost any data. But, if my worries are not unfounded, and real damage could happen in either situation 1 or 2, then my hope is that there is a way to detect it and prevent against it. My Question(s) Could this be because modern operating systems are designed to ensure that nothing is lost in these scenarios? Could this be because modern software is designed to ensure that nothing lost? What about modern hardware design? What measures are in place when you pull the power plug? My question is, for both of these scenarios, what exactly can go wrong, and what steps should be taken to fix it? I'm under the impression that one thing that can go wrong is some programs might not have flushed their data to the disk, so any highly recent data that was supposed to be written to the disk (say, a few seconds before the power pull) might be lost. But what about beyond that? And can this very issue of 5-second data loss screw up a system? What about corruption of random files hiding somewhere in the huge forest of files on my hard drives? What about hardware damage? What Would Help Me Most Detailed descriptions about what goes on internally when you either kill -9 a process or pull the power on the whole system. (it seems instant, but can someone slow it down for me?) Explanations of all things that could go wrong in these scenarios, along with (rough of course) probabilities (i.e., this is very unlikely, but this is likely)... Descriptions of measures in place in modern hardware, operating systems, and software, to prevent damage or corruption when these scenarios occur. (to comfort me) Instructions for what to do after a kill -9 or a power pull, beyond "verifying the disk", in order to truly make sure nothing is corrupt or damaged somewhere on the drive. Measures that can be taken to fortify a computer setup so that if something has to be killed or the power has to be pulled, any potential damage is mitigated. Thanks so much!

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• Installer Reboots at "Detecting hardware" (disks and other hardware) on all recent Server Installs

  - by Ryan Rosario

  I have a very frustrating problem with my PC. I cannot install any recent version of Ubuntu Server (or even Desktop) since 9.04 even using the text-based installer. I boot from a USB stick created by Unetbootin (I also tried other methods such as startup disk creator with no difference). On the Server installer, it gets to "Detecting Hardware" (the second one about disks and all other hardware, not network hardware) and then either hangs at 0% (waited 24 hours), or reboots after a minute or two. My system (late 2007): ASUS P5NSLI motherboard Intel Core 2 Duo E6600 2.4Ghz 2 x 1GB Corsair 667MHz RAM nVidia GeForce 6600 I have unplugged everything (including the only hard disk, CD-ROMs and floppy). I have only one stick of RAM (tried each one to no avail) and am booting the installer from a USB stick (booting from CD-ROM yields the same problem). I also tried several of the boot options (nomodeset, nousb, acpi=off, noapic, i915.modeset=1/0, xforcevesa) in all combinations) to no avail. The only active parts of my system are the video card, mouse, keyboard and USB stick. I have also updated the BIOS to the most recent version. (FWIW, on the Desktop installer, I get a black screen after hitting the Install option.) Even after removing "quiet" I am unable to see what kernel panic is occurring (or not occurring) to cause the install to crash. I am only able to save the debug logs via a simple webserver in the installer. After the last line (I repeatedly refreshed), the server stops responding and the installer hangs or reboots: Jan 2 01:04:03 main-menu[302]: INFO: Menu item 'disk-detect' selected Jan 2 01:04:04 kernel: [ 309.154372] sata_nv 0000:00:0e.0: version 3.5 Jan 2 01:04:04 kernel: [ 309.154409] sata_nv 0000:00:0e.0: Using SWNCQ mode Jan 2 01:04:04 kernel: [ 309.154531] sata_nv 0000:00:0e.0: setting latency timer to 64 Jan 2 01:04:04 kernel: [ 309.164442] scsi0 : sata_nv Jan 2 01:04:04 kernel: [ 309.167610] scsi1 : sata_nv Jan 2 01:04:04 kernel: [ 309.167762] ata1: SATA max UDMA/133 cmd 0x9f0 ctl 0xbf0 bmdma 0xd400 irq 10 Jan 2 01:04:04 kernel: [ 309.167774] ata2: SATA max UDMA/133 cmd 0x970 ctl 0xb70 bmdma 0xd408 irq 10 Jan 2 01:04:04 kernel: [ 309.167948] sata_nv 0000:00:0f.0: Using SWNCQ mode Jan 2 01:04:04 kernel: [ 309.168071] sata_nv 0000:00:0f.0: setting latency timer to 64 Jan 2 01:04:04 kernel: [ 309.171931] scsi2 : sata_nv Jan 2 01:04:04 kernel: [ 309.173793] scsi3 : sata_nv Jan 2 01:04:04 kernel: [ 309.173943] ata3: SATA max UDMA/133 cmd 0x9e0 ctl 0xbe0 bmdma 0xe800 irq 11 Jan 2 01:04:04 kernel: [ 309.173954] ata4: SATA max UDMA/133 cmd 0x960 ctl 0xb60 bmdma 0xe808 irq 11 Jan 2 01:04:04 kernel: [ 309.174061] pata_amd 0000:00:0d.0: version 0.4.1 Jan 2 01:04:04 kernel: [ 309.174160] pata_amd 0000:00:0d.0: setting latency timer to 64 Jan 2 01:04:04 kernel: [ 309.177045] scsi4 : pata_amd Jan 2 01:04:04 kernel: [ 309.178628] scsi5 : pata_amd Jan 2 01:04:04 kernel: [ 309.178801] ata5: PATA max UDMA/133 cmd 0x1f0 ctl 0x3f6 bmdma 0xf000 irq 14 Jan 2 01:04:04 kernel: [ 309.178811] ata6: PATA max UDMA/133 cmd 0x170 ctl 0x376 bmdma 0xf008 irq 15 Jan 2 01:04:04 net/hw-detect.hotplug: Detected hotpluggable network interface eth0 Jan 2 01:04:04 net/hw-detect.hotplug: Detected hotpluggable network interface lo Jan 2 01:04:04 kernel: [ 309.485062] ata3: SATA link down (SStatus 0 SControl 300) Jan 2 01:04:04 kernel: [ 309.633094] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Jan 2 01:04:04 kernel: [ 309.641647] ata1.00: ATA-8: ST31000528AS, CC38, max UDMA/133 Jan 2 01:04:04 kernel: [ 309.641658] ata1.00: 1953525168 sectors, multi 1: LBA48 NCQ (depth 31/32) Jan 2 01:04:04 kernel: [ 309.657614] ata1.00: configured for UDMA/133 Jan 2 01:04:04 kernel: [ 309.657969] scsi 0:0:0:0: Direct-Access ATA ST31000528AS CC38 PQ: 0 ANSI: 5 Jan 2 01:04:04 kernel: [ 309.658482] sd 0:0:0:0: Attached scsi generic sg0 type 0 Jan 2 01:04:04 kernel: [ 309.658588] sd 0:0:0:0: [sda] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB) Jan 2 01:04:04 kernel: [ 309.658812] sd 0:0:0:0: [sda] Write Protect is off Jan 2 01:04:04 kernel: [ 309.658823] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 Jan 2 01:04:04 kernel: [ 309.658918] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA Jan 2 01:04:04 kernel: [ 309.675630] sda: sda1 sda2 Jan 2 01:04:04 kernel: [ 309.676440] sd 0:0:0:0: [sda] Attached SCSI disk Jan 2 01:04:05 kernel: [ 309.969102] ata2: SATA link down (SStatus 0 SControl 300) Jan 2 01:04:05 kernel: [ 310.281137] ata4: SATA link down (SStatus 0 SControl 300) Anybody have any additional ideas I could try? I am getting ready to just toss the motherboard.

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• Converting an Oracle VM VirtualBox VM into an Oracle VM Server image

  - by wim.coekaerts

  As we are working on tighter seemless moving of VM's between the 2 products, here are a few simple steps to convert an existing Oracle VM VirtualBox image over. Steps involved to make it easy/straightforward : (1) When creating a VM in Virtualbox, using Oracle Linux as an example, make sure that /etc/fstab only uses labels. Do not use hardcoded device names. instead of an entry /dev/sda1 /u01 ext3 defaults 1 1 use LABEL=foo /u01 ext3 defaults 1 1 for more info on labels : man e2label or use a logical volume /dev/VolGroup00/LVfoo /u01 ext3 defaults 1 1 Doing so will make it easier to have an OS boot up on a different hypervisor with potentially different device names. For instance, the VirtualBox VM might expose a scsi driver while in Oracle VM Server you might end up with an ide disk, this then changes /dev/sda to /dev/hda. (2) If you have a VM created that you want to convert, then shut down the VM in VirtualBox and convert the image files : go the the directory that contains your HardDisk image files (.VirtualBox/HardDisks/* as an example) for each of the virtual disks run the following command : VBoxManage clonehd virtualdiskfilename.vdi system.img --format raw where virtualdiskfilename.vdi is the original VBox VM file (this can also be a vmdk file) and system.img is the name of the virtualdisk for Oracle VM. this can be any filename as well, I typically use system.img to specify the boot disk (as is common for Oracle VM template creation) (3) create a vm.cfg To run a VM converted from VirtualBox, you have to create a vm.cfg for Oracle VM server that creates an HVM guest. The easiest is to use a simple hvm vm.cfg and change it for your vm. I have an example here : acpi = 1 apic = 1 builder = 'hvm' device_model = '/usr/lib/xen/bin/qemu-dm' disk = ['file:system.img,hda,w', 'file:oracle.img,hdb,w',',hdc:cdrom,r',] kernel = '/usr/lib/xen/boot/hvmloader' memory = '1024' name = 'vmname' on_crash = 'restart' on_reboot = 'restart' pae = 1 serial = 'pty' timer_mode = '0' usbdevice = 'tablet' vcpus = 1 vif = ['bridge=xenbr0,type=ioemu'] vif_other_config = [] vnc = 1 vncconsole = 1 vnclisten = '0.0.0.0' vncpasswd = '' vncunused = 1 If you take the above vm.cfg, all you need to do - modify disk = (add your virtual disks in there) - modify memory = (amount of memory your VM needs) - modify name = (enter a name for your VM here) - modify vif = (might want to replace bridge=xenbr0 to the bridge you want to use) if you want more than 1 vcpu or other changes of course you have to make those as well. (4) copy this set of files onto your Oracle VM server or onto a webserver in a subdirectory and import the template through Oracle VM Manager. You can also just start the vm using xm create vm.cfg if you like. And that's it. As I said, we are working on automation around all this but it is relatively trivial to convert VM's over as long as you take the basic issues into account. Primarily the set up of the filesystems and the use of labels in /etc/fstab. There are other potential things to look at, such as network config. If you want to make that part clean then prior to shutting down the VM change /etc/modprobe.conf and/or add the mac address of the VM into the vm.cfg in the vifs line. The good thing, at least with Linux, is that even tho the virtual hardware changes, Linux will deal with it just fine (e1000 vs 8139 realtek, ide vs scsi etc). hope this helps.

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• How do I repair the corrupted files found by sfc /scannow? "Windows Resource Protection found corrupt files but was unable to fix some of them."

  - by galacticninja

  After running chkdsk C: /F /R and finding out that my hard disk has 24 KB in bad sectors (log is posted below), I decided to run Windows 7's System File Checker utility (sfc /scannow). SFC showed the ff. message after I ran it: "Windows Resource Protection found corrupt files but was unable to fix some of them. Details are included in the CBS.Log windir\Logs\CBS\CBS.log." Since the CBS.log file is too large, I ran findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >"%userprofile%\Desktop\sfcdetails.txt" (as per Microsoft's KB 928228 article) to only get the log text pertaining to the corrupt files. (log is also posted below) How do I troubleshoot and repair the corrupted files mentioned by sfc /scannow? My OS is Windows 7, 64-bit. chkdsk log Checking file system on C: The type of the file system is NTFS. A disk check has been scheduled. Windows will now check the disk. CHKDSK is verifying files (stage 1 of 5)... 936192 file records processed. File verification completed. 25238 large file records processed. 0 bad file records processed. 4 EA records processed. 44 reparse records processed. CHKDSK is verifying indexes (stage 2 of 5)... 1051640 index entries processed. Index verification completed. 0 unindexed files scanned. 0 unindexed files recovered. CHKDSK is verifying security descriptors (stage 3 of 5)... 936192 file SDs/SIDs processed. Cleaning up 24 unused index entries from index $SII of file 0x9. Cleaning up 24 unused index entries from index $SDH of file 0x9. Cleaning up 24 unused security descriptors. Security descriptor verification completed. 57725 data files processed. CHKDSK is verifying Usn Journal... 36994248 USN bytes processed. Usn Journal verification completed. CHKDSK is verifying file data (stage 4 of 5)... 936176 files processed. File data verification completed. CHKDSK is verifying free space (stage 5 of 5)... 306238 free clusters processed. Free space verification is complete. Adding 1 bad clusters to the Bad Clusters File. Correcting errors in the Volume Bitmap. Windows has made corrections to the file system. 488282111 KB total disk space. 485595420 KB in 766458 files. 401856 KB in 57726 indexes. 24 KB in bad sectors. 1059863 KB in use by the system. 65536 KB occupied by the log file. 1224948 KB available on disk. 4096 bytes in each allocation unit. 122070527 total allocation units on disk. 306237 allocation units available on disk. Internal Info: 00 49 0e 00 81 93 0c 00 34 01 17 00 00 00 00 00 .I......4....... 6b 29 00 00 2c 00 00 00 00 00 00 00 00 00 00 00 k)..,........... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ sfc /scannow log (through findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >"%userprofile%\Desktop\sfcdetails.txt") Note: The full log is at http://pastebin.com/raw.php?i=gTEGZmWj . I've only quoted parts of the full log below (mostly from the last part), as the full log won't fit within the character limit for questions. I've added it to serve as a preview. ... 2013-12-28 19:37:50, Info CSI00000542 [SR] Beginning Verify and Repair transaction 2013-12-28 19:37:55, Info CSI00000544 [SR] Verify complete 2013-12-28 19:37:56, Info CSI00000545 [SR] Verifying 95 (0x000000000000005f) components 2013-12-28 19:37:56, Info CSI00000546 [SR] Beginning Verify and Repair transaction 2013-12-28 19:38:03, Info CSI00000548 [SR] Verify complete 2013-12-28 19:38:03, Info CSI00000549 [SR] Repairing 43 (0x000000000000002b) components 2013-12-28 19:38:03, Info CSI0000054a [SR] Beginning Verify and Repair transaction ... 2013-12-28 19:38:15, Info CSI00000730 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:62{31}]"GroupPolicy-Admin-Gpedit-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000733 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:30{15}]"frs-core-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000736 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:26{13}]"gpmgmt-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000739 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:74{37}]"MediaServer-ASPAdmin-Migration-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI0000073c [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:36{18}]"Ldap-Client-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI0000073f [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:38{19}]"iSNS_Service-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000742 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:76{38}]"MediaServer-Multicast-Migration-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000745 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:78{39}]"Kerberos-Key-Distribution-Center-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000748 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:86{43}]"GroupPolicy-CSE-SoftwareInstallation-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI0000074b [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:28{14}]"ieframe-dl.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI0000074e [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:76{38}]"GroupPolicy-Admin-Gpedit-Snapin-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000751 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:32{16}]"IPSec-Svc-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000754 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:22{11}]"HTTP-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000757 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:56{28}]"MediaServer-Migration-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI0000075a [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:26{13}]"GPBase-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI0000075d [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:38{19}]"IasMigPlugin-DL.man"; source file in store is also corrupted 2013-12-28 19:38:15, Info CSI00000760 [SR] Could not reproject corrupted file [ml:520{260},l:84{42}]"\??\C:\Windows\System32\migwiz\dlmanifests"\[l:50{25}]"International-Core-DL.man"; source file in store is also corrupted 2013-12-28 19:38:16, Info CSI00000762 [SR] Cannot repair member file [l:24{12}]"wbemdisp.dll" of Microsoft-Windows-WMI-Scripting, Version = 6.1.7600.16385, pA = PROCESSOR_ARCHITECTURE_INTEL (0), Culture neutral, VersionScope = 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName neutral, PublicKey neutral in the store, hash mismatch 2013-12-28 19:38:16, Info CSI00000763 [SR] This component was referenced by [l:202{101}]"Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~6.1.7601.17514.WindowsFoundationDelivery" 2013-12-28 19:38:16, Info CSI00000766 [SR] Could not reproject corrupted file [ml:58{29},l:56{28}]"\??\C:\Windows\SysWOW64\wbem"\[l:24{12}]"wbemdisp.dll"; source file in store is also corrupted 2013-12-28 19:38:16, Info CSI00000768 [SR] Cannot repair member file [l:56{28}]"Microsoft.MediaCenter.UI.dll" of Microsoft.MediaCenter.UI, Version = 6.1.7601.17514, pA = PROCESSOR_ARCHITECTURE_MSIL (8), Culture neutral, VersionScope = 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName neutral, PublicKey neutral in the store, hash mismatch 2013-12-28 19:38:16, Info CSI00000769 [SR] This component was referenced by [l:176{88}]"Microsoft-Windows-MediaCenter-Package~31bf3856ad364e35~amd64~~6.1.7601.17514.MediaCenter" 2013-12-28 19:38:16, Info CSI0000076c [SR] Could not reproject corrupted file [ml:520{260},l:40{20}]"\??\C:\Windows\ehome"\[l:56{28}]"Microsoft.MediaCenter.UI.dll"; source file in store is also corrupted 2013-12-28 19:38:16, Info CSI0000076e [SR] Cannot repair member file [l:24{12}]"ReAgentc.exe" of Microsoft-Windows-WinRE-RecoveryTools, Version = 6.1.7601.17514, pA = PROCESSOR_ARCHITECTURE_INTEL (0), Culture neutral, VersionScope = 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName neutral, PublicKey neutral in the store, hash mismatch 2013-12-28 19:38:16, Info CSI0000076f [SR] This component was referenced by [l:202{101}]"Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~6.1.7601.17514.WindowsFoundationDelivery" 2013-12-28 19:38:16, Info CSI00000772 [SR] Could not reproject corrupted file [ml:48{24},l:46{23}]"\??\C:\Windows\SysWOW64"\[l:24{12}]"ReAgentc.exe"; source file in store is also corrupted 2013-12-28 19:38:16, Info CSI00000774 [SR] Cannot repair member file [l:82{41}]"System.Management.Automation.dll-Help.xml" of Microsoft-Windows-PowerShell-PreLoc.Resources, Version = 6.1.7600.16385, pA = PROCESSOR_ARCHITECTURE_AMD64 (9), Culture = [l:10{5}]"en-US", VersionScope = 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName neutral, PublicKey neutral in the store, hash mismatch 2013-12-28 19:38:16, Info CSI00000775 [SR] This component was referenced by [l:266{133}]"Microsoft-Windows-Client-Features-Package~31bf3856ad364e35~amd64~en-US~6.1.7601.17514.Microsoft-Windows-Client-Features-Language-Pack" 2013-12-28 19:38:16, Info CSI00000778 [SR] Could not reproject corrupted file [ml:520{260},l:104{52}]"\??\C:\Windows\System32\WindowsPowerShell\v1.0\en-US"\[l:82{41}]"System.Management.Automation.dll-Help.xml"; source file in store is also corrupted 2013-12-28 19:38:16, Info CSI0000077a [SR] Cannot repair member file [l:18{9}]"hlink.dll" of Microsoft-Windows-HLink, Version = 6.1.7600.16385, pA = PROCESSOR_ARCHITECTURE_INTEL (0), Culture neutral, VersionScope = 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName neutral, PublicKey neutral in the store, hash mismatch 2013-12-28 19:38:16, Info CSI0000077b [SR] This component was referenced by [l:202{101}]"Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~6.1.7601.17514.WindowsFoundationDelivery" 2013-12-28 19:38:16, Info CSI0000077e [SR] Could not reproject corrupted file [ml:48{24},l:46{23}]"\??\C:\Windows\SysWOW64"\[l:18{9}]"hlink.dll"; source file in store is also corrupted 2013-12-28 19:38:16, Info CSI00000780 [SR] Repair complete 2013-12-28 19:38:16, Info CSI00000781 [SR] Committing transaction 2013-12-28 19:38:19, Info CSI00000785 [SR] Verify and Repair Transaction completed. All files and registry keys listed in this transaction have been successfully repaired

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• MySQL query, 2 similar servers, 2 minute difference in execution times

  - by mr12086

  I had a similar question on stack overflow, but it seems to be more server/mysql setup related than coding. The queries below all execute instantly on our development server where as they can take upto 2 minutes 20 seconds. The query execution time seems to be affected by home ambiguous the LIKE string's are. If they closely match a country that has few matches it will take less time, and if you use something like 'ge' for germany - it will take longer to execute. But this doesn't always work out like that, at times its quite erratic. Sending data appears to be the culprit but why and what does that mean. Also memory on production looks to be quite low (free memory)? Production: Intel Quad Xeon E3-1220 3.1GHz 4GB DDR3 2x 1TB SATA in RAID1 Network speed 100Mb Ubuntu Development Intel Core i3-2100, 2C/4T, 3.10GHz 500 GB SATA - No RAID 4GB DDR3 UPDATE 2 : mysqltuner output: [prod] -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.1.61-0ubuntu0.10.04.1 [OK] Operating on 64-bit architecture -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster [--] Data in MyISAM tables: 103M (Tables: 180) [--] Data in InnoDB tables: 491M (Tables: 19) [!!] Total fragmented tables: 38 -------- Security Recommendations ------------------------------------------- [OK] All database users have passwords assigned -------- Performance Metrics ------------------------------------------------- [--] Up for: 77d 4h 6m 1s (53M q [7.968 qps], 14M conn, TX: 87B, RX: 12B) [--] Reads / Writes: 98% / 2% [--] Total buffers: 58.0M global + 2.7M per thread (151 max threads) [OK] Maximum possible memory usage: 463.8M (11% of installed RAM) [OK] Slow queries: 0% (12K/53M) [OK] Highest usage of available connections: 22% (34/151) [OK] Key buffer size / total MyISAM indexes: 16.0M/10.6M [OK] Key buffer hit rate: 98.7% (162M cached / 2M reads) [OK] Query cache efficiency: 20.7% (7M cached / 36M selects) [!!] Query cache prunes per day: 3934 [OK] Sorts requiring temporary tables: 1% (3K temp sorts / 230K sorts) [!!] Joins performed without indexes: 71068 [OK] Temporary tables created on disk: 24% (3M on disk / 13M total) [OK] Thread cache hit rate: 99% (690 created / 14M connections) [!!] Table cache hit rate: 0% (64 open / 85M opened) [OK] Open file limit used: 12% (128/1K) [OK] Table locks acquired immediately: 99% (16M immediate / 16M locks) [!!] InnoDB data size / buffer pool: 491.9M/8.0M -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance Enable the slow query log to troubleshoot bad queries Adjust your join queries to always utilize indexes Increase table_cache gradually to avoid file descriptor limits Variables to adjust: query_cache_size (> 16M) join_buffer_size (> 128.0K, or always use indexes with joins) table_cache (> 64) innodb_buffer_pool_size (>= 491M) [dev] -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.1.62-0ubuntu0.11.10.1 [!!] Switch to 64-bit OS - MySQL cannot currently use all of your RAM -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster [--] Data in MyISAM tables: 185M (Tables: 632) [--] Data in InnoDB tables: 967M (Tables: 38) [!!] Total fragmented tables: 73 -------- Security Recommendations ------------------------------------------- [OK] All database users have passwords assigned -------- Performance Metrics ------------------------------------------------- [--] Up for: 1d 2h 26m 9s (5K q [0.058 qps], 1K conn, TX: 4M, RX: 1M) [--] Reads / Writes: 99% / 1% [--] Total buffers: 58.0M global + 2.7M per thread (151 max threads) [OK] Maximum possible memory usage: 463.8M (11% of installed RAM) [OK] Slow queries: 0% (0/5K) [OK] Highest usage of available connections: 1% (2/151) [OK] Key buffer size / total MyISAM indexes: 16.0M/18.6M [OK] Key buffer hit rate: 99.9% (60K cached / 36 reads) [OK] Query cache efficiency: 44.5% (1K cached / 2K selects) [OK] Query cache prunes per day: 0 [OK] Sorts requiring temporary tables: 0% (0 temp sorts / 44 sorts) [OK] Temporary tables created on disk: 24% (162 on disk / 666 total) [OK] Thread cache hit rate: 99% (2 created / 1K connections) [!!] Table cache hit rate: 1% (64 open / 4K opened) [OK] Open file limit used: 8% (88/1K) [OK] Table locks acquired immediately: 100% (1K immediate / 1K locks) [!!] InnoDB data size / buffer pool: 967.7M/8.0M -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance Enable the slow query log to troubleshoot bad queries Increase table_cache gradually to avoid file descriptor limits Variables to adjust: table_cache (> 64) innodb_buffer_pool_size (>= 967M) UPDATE 1: When testing the queries listed here there is usually no more than one other query taking place, and usually none. Because production is actually handling apache requests that development gets very few of as it's only myself and 1 other who accesses it - could the 4GB of RAM be getting exhausted by using the single machine for both apache and mysql server? Production: sudo hdparm -tT /dev/sda /dev/sda: Timing cached reads: 24872 MB in 2.00 seconds = 12450.72 MB/sec Timing buffered disk reads: 368 MB in 3.00 seconds = 122.49 MB/sec sudo hdparm -tT /dev/sdb /dev/sdb: Timing cached reads: 24786 MB in 2.00 seconds = 12407.22 MB/sec Timing buffered disk reads: 350 MB in 3.00 seconds = 116.53 MB/sec Server version(mysql + ubuntu versions): 5.1.61-0ubuntu0.10.04.1 Development: sudo hdparm -tT /dev/sda /dev/sda: Timing cached reads: 10632 MB in 2.00 seconds = 5319.40 MB/sec Timing buffered disk reads: 400 MB in 3.01 seconds = 132.85 MB/sec Server version(mysql + ubuntu versions): 5.1.62-0ubuntu0.11.10.1 ORIGINAL DATA : This query is NOT the query in question but is related so ill post it. SELECT f.form_question_has_answer_id FROM form_question_has_answer f INNER JOIN project_company_has_user p ON f.form_question_has_answer_user_id = p.project_company_has_user_user_id INNER JOIN company c ON p.project_company_has_user_company_id = c.company_id INNER JOIN project p2 ON p.project_company_has_user_project_id = p2.project_id INNER JOIN user u ON p.project_company_has_user_user_id = u.user_id INNER JOIN form f2 ON p.project_company_has_user_project_id = f2.form_project_id WHERE (f2.form_template_name = 'custom' AND p.project_company_has_user_garbage_collection = 0 AND p.project_company_has_user_project_id = '29') AND (LCASE(c.company_country) LIKE '%ge%' OR LCASE(c.company_country) LIKE '%abcde%') AND f.form_question_has_answer_form_id = '174' And the explain plan for the above query is, run on both dev and production produce the same plan. +----+-------------+-------+--------+----------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------+---------+----------------------------------------------------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+----------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------+---------+----------------------------------------------------+------+-------------+ | 1 | SIMPLE | p2 | const | PRIMARY | PRIMARY | 4 | const | 1 | Using index | | 1 | SIMPLE | f | ref | form_question_has_answer_form_id,form_question_has_answer_user_id | form_question_has_answer_form_id | 4 | const | 796 | Using where | | 1 | SIMPLE | u | eq_ref | PRIMARY | PRIMARY | 4 | new_klarents.f.form_question_has_answer_user_id | 1 | Using index | | 1 | SIMPLE | p | ref | project_company_has_user_unique_key,project_company_has_user_user_id,project_company_has_user_company_id,project_company_has_user_project_id | project_company_has_user_user_id | 4 | new_klarents.f.form_question_has_answer_user_id | 1 | Using where | | 1 | SIMPLE | f2 | ref | form_project_id | form_project_id | 4 | const | 15 | Using where | | 1 | SIMPLE | c | eq_ref | PRIMARY | PRIMARY | 4 | new_klarents.p.project_company_has_user_company_id | 1 | Using where | +----+-------------+-------+--------+----------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------+---------+----------------------------------------------------+------+-------------+ This query takes 2 minutes ~20 seconds to execute. The query that is ACTUALLY being run on the server is this one: SELECT COUNT(*) AS num_results FROM (SELECT f.form_question_has_answer_id FROM form_question_has_answer f INNER JOIN project_company_has_user p ON f.form_question_has_answer_user_id = p.project_company_has_user_user_id INNER JOIN company c ON p.project_company_has_user_company_id = c.company_id INNER JOIN project p2 ON p.project_company_has_user_project_id = p2.project_id INNER JOIN user u ON p.project_company_has_user_user_id = u.user_id INNER JOIN form f2 ON p.project_company_has_user_project_id = f2.form_project_id WHERE (f2.form_template_name = 'custom' AND p.project_company_has_user_garbage_collection = 0 AND p.project_company_has_user_project_id = '29') AND (LCASE(c.company_country) LIKE '%ge%' OR LCASE(c.company_country) LIKE '%abcde%') AND f.form_question_has_answer_form_id = '174' GROUP BY f.form_question_has_answer_id;) dctrn_count_query; With explain plans (again same on dev and production): +----+-------------+-------+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------+---------+----------------------------------------------------+------+------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------+---------+----------------------------------------------------+------+------------------------------+ | 1 | PRIMARY | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Select tables optimized away | | 2 | DERIVED | p2 | const | PRIMARY | PRIMARY | 4 | | 1 | Using index | | 2 | DERIVED | f | ref | form_question_has_answer_form_id,form_question_has_answer_user_id | form_question_has_answer_form_id | 4 | | 797 | Using where | | 2 | DERIVED | p | ref | project_company_has_user_unique_key,project_company_has_user_user_id,project_company_has_user_company_id,project_company_has_user_project_id,project_company_has_user_garbage_collection | project_company_has_user_user_id | 4 | new_klarents.f.form_question_has_answer_user_id | 1 | Using where | | 2 | DERIVED | f2 | ref | form_project_id | form_project_id | 4 | | 15 | Using where | | 2 | DERIVED | c | eq_ref | PRIMARY | PRIMARY | 4 | new_klarents.p.project_company_has_user_company_id | 1 | Using where | | 2 | DERIVED | u | eq_ref | PRIMARY | PRIMARY | 4 | new_klarents.p.project_company_has_user_user_id | 1 | Using where; Using index | +----+-------------+-------+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------+---------+----------------------------------------------------+------+------------------------------+ On the production server the information I have is as follows. Upon execution: +-------------+ | num_results | +-------------+ | 3 | +-------------+ 1 row in set (2 min 14.28 sec) Show profile: +--------------------------------+------------+ | Status | Duration | +--------------------------------+------------+ | starting | 0.000016 | | checking query cache for query | 0.000057 | | Opening tables | 0.004388 | | System lock | 0.000003 | | Table lock | 0.000036 | | init | 0.000030 | | optimizing | 0.000016 | | statistics | 0.000111 | | preparing | 0.000022 | | executing | 0.000004 | | Sorting result | 0.000002 | | Sending data | 136.213836 | | end | 0.000007 | | query end | 0.000002 | | freeing items | 0.004273 | | storing result in query cache | 0.000010 | | logging slow query | 0.000001 | | logging slow query | 0.000002 | | cleaning up | 0.000002 | +--------------------------------+------------+ On development the results are as follows. +-------------+ | num_results | +-------------+ | 3 | +-------------+ 1 row in set (0.08 sec) Again the profile for this query: +--------------------------------+----------+ | Status | Duration | +--------------------------------+----------+ | starting | 0.000022 | | checking query cache for query | 0.000148 | | Opening tables | 0.000025 | | System lock | 0.000008 | | Table lock | 0.000101 | | optimizing | 0.000035 | | statistics | 0.001019 | | preparing | 0.000047 | | executing | 0.000008 | | Sorting result | 0.000005 | | Sending data | 0.086565 | | init | 0.000015 | | optimizing | 0.000006 | | executing | 0.000020 | | end | 0.000004 | | query end | 0.000004 | | freeing items | 0.000028 | | storing result in query cache | 0.000005 | | removing tmp table | 0.000008 | | closing tables | 0.000008 | | logging slow query | 0.000002 | | cleaning up | 0.000005 | +--------------------------------+----------+ If i remove user and/or project innerjoins the query is reduced to 30s. Last bit of information I have: Mysqlserver and Apache are on the same box, there is only one box for production. Production output from top: before & after. top - 15:43:25 up 78 days, 12:11, 4 users, load average: 1.42, 0.99, 0.78 Tasks: 162 total, 2 running, 160 sleeping, 0 stopped, 0 zombie Cpu(s): 0.1%us, 50.4%sy, 0.0%ni, 49.5%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 4037868k total, 3772580k used, 265288k free, 243704k buffers Swap: 3905528k total, 265384k used, 3640144k free, 1207944k cached top - 15:44:31 up 78 days, 12:13, 4 users, load average: 1.94, 1.23, 0.87 Tasks: 160 total, 2 running, 157 sleeping, 0 stopped, 1 zombie Cpu(s): 0.2%us, 50.6%sy, 0.0%ni, 49.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 4037868k total, 3834300k used, 203568k free, 243736k buffers Swap: 3905528k total, 265384k used, 3640144k free, 1207804k cached But this isn't a good representation of production's normal status so here is a grab of it from today outside of executing the queries. top - 11:04:58 up 79 days, 7:33, 4 users, load average: 0.39, 0.58, 0.76 Tasks: 156 total, 1 running, 155 sleeping, 0 stopped, 0 zombie Cpu(s): 3.3%us, 2.8%sy, 0.0%ni, 93.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 4037868k total, 3676136k used, 361732k free, 271480k buffers Swap: 3905528k total, 268736k used, 3636792k free, 1063432k cached Development: This one doesn't change during or after. top - 15:47:07 up 110 days, 22:11, 7 users, load average: 0.17, 0.07, 0.06 Tasks: 210 total, 2 running, 208 sleeping, 0 stopped, 0 zombie Cpu(s): 0.1%us, 0.2%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 4111972k total, 1821100k used, 2290872k free, 238860k buffers Swap: 4183036k total, 66472k used, 4116564k free, 921072k cached

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• Displaying wait cursor in while backgroundworker is running

  - by arc1880

  During the start of my windows application, I have to make a call to a web service to retrieve some default data to load onto my application. During the load of the form, I run a backgroundworker to retrieve this data. I want to display the wait cursor until this data is retrieved. How would I do this? I've tried setting the wait cursor before calling the backgroundworker to run. When I report a progress of 100 then I set it back to the default cursor. The wait cursor comes up but when I move the mouse it disappears. Environment: Windows 7 Pro 64-bit VS2010 C# .NET 4.0 Windows Forms EDIT: I am setting the cursor the way Jay Riggs suggested. It only works if I don't move the mouse. **UPDATE: I have created a button click which does the following: When I do the button click and move my mouse, the wait cursor appears regardless if I move my mouse or not. void BtnClick() { Cursor = Cursors.WaitCursor; Thread.Sleep(8000); Cursor = Cursors.Default; } If I do the following: I see the wait cursor and when I move the mouse it disappears inside the form. If I move to my status bar or the menu bar the wait cursor appears. Cursor = Cursors.WaitCursor; if (!backgroundWorker.IsBusy) { backGroundWorker.RunWorkerAsync(); } void backGroundWorkerDoWork(object sender, DoWorkEventArgs e) { Thread.Sleep(8000); } void backGroundWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { Cursor = Cursors.Default; } If I do the following: The wait cursor appears and when I move the mouse it still appears but will sometimes flicker off and on when moving in text fields. if (!backgroundWorker.IsBusy) { backGroundWorker.RunWorkerAsync(); } void backGroundWorkerDoWork(object sender, DoWorkEventArgs e) { UseWaitCursor = true; Thread.Sleep(8000); } void backGroundWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { UseWaitCursor = false; }

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• DataContractSerializer and deserializing web service response types

  - by matra

  Hi, I am using calling web services and using WCF generated service-reference on the client. I have saved XML responses that are received from test service to disk (without SOAP envelope and body tags) I would like to load them from disk and create objects from them. Lets' take the following method from my web service: SomeMethodResponse SomeMethod(SomeMethodRequest req) I manually (through SOAP UI) save the response to disk to file, Sample response: < SomeMethodResponse xmlns="http://myNamespace"> <SomeMember1>value</SomeMember1> </SomeMethodResponse xmlns="http://myNamespace"> Then I try to deserialize the object from file using: DataContractSerializer dcs = new DataContractSerializer(typeof(SomeMethodResponse)) This fails – the serializer complains with the error, that it is expecting element in namespace 'http://schemas.datacontract.org/2004/07', but found element in 'http://myNamespace'. Question: Why does the DataContractSerializer not use the namespace, that is declared on SomeMethodResponseType with XmlTypeAttribute(Namespace="http://myNamespace")? I can work around this by explicitly providing the namespace and the root element to DataContractSerializer constructor. But then it fails with message similar to: Error in line X position Y (last line of the XMLdocument). 'EndElement' 'SomeMethodResponse from namespace 'httpmyNapespace’ is not expected. Expecting element 'someNameField'. SomeName is an element in the XSD that web service is using. It is also a property on the SomeMethodResponse type, backed by the private field called someNameField. It looks like DataContractSerializer is trying to deserialize the fields in addition to properties. How can I deserailize XML that I have saved from disk and get back the object of same type that SomeMethod is returning? Thanks, Matra

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• Visual studio 2010 setup project problem.

  - by Guru

  Hi there, I've made an application that uses .NET framework 3.5 SP1 and SQL Server 2008 Express. Application is fine and now i'm going to to make a setup project for this. When I first build my setup it was fine as all the prerequisites were not included in setup. But I want my setup to install .NET 3.5 SP1 and SQL SERVER 2008 Express also. So for this I've changed the options in setup project's properties from "Download prerequisites from following location" to "Download prerequisites from the same location as my application". In addition to that I've also checked the options above like .NET 3.5 SP1 and SQL Server 2008 Express etc. After doing all this I build my project again. This time I'm Getting 57 Errors. Error 1 The install location for prerequisites has not been set to 'component vendor's web site' and the file 'DotNetFX35SP1\dotNetFX20\aspnet.msp' in item '.NET Framework 3.5 SP1' can not be located on disk. See Help for more information. D:\MindStrike Setup\MindStrike Setup.vdproj MindStrike Setup Error 2 The install location for prerequisites has not been set to 'component vendor's web site' and the file 'DotNetFX35SP1\dotNetFX20\aspnet_64.msp' in item '.NET Framework 3.5 SP1' can not be located on disk. See Help for more information. D:\MindStrike Setup\MindStrike Setup.vdproj MindStrike Setup Error 3 The install location for prerequisites has not been set to 'component vendor's web site' and the file 'DotNetFX35SP1\dotNetFX20\clr.msp' in item '.NET Framework 3.5 SP1' can not be located on disk. See Help for more information. D:\MindStrike Setup\MindStrike Setup.vdproj MindStrike Setup Error 4 The install location for prerequisites has not been set to 'component vendor's web site' and the file 'DotNetFX35SP1\dotNetFX20\clr_64.msp' in item '.NET Framework 3.5 SP1' can not be located on disk. See Help for more information. D:\MindStrike Setup\MindStrike Setup.vdproj MindStrike Setup As the question will become too large so I'm just pasting 3 errors but there are totally 57 errors. Please help me . Thanks in advance Guru

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• Using Sendkeys in python to press {F12} results in other keys pressed?

  - by ThantiK

  import time from ctypes import * import win32gui import win32com.client as comclt X = 119 Y = 53 def PILColorToRGB(pil_color): """ convert a PIL-compatible integer into an (r, g, b) tuple """ hexstr = '%06x' % pil_color # reverse byte order r, g, b = hexstr[4:], hexstr[2:4], hexstr[:2] r, g, b = [int(n, 16) for n in (r, g, b)] return (r, g, b) wsh = comclt.Dispatch("WScript.Shell") w = win32gui user = windll.LoadLibrary("c:\\windows\\system32\\user32.dll") h = user.GetDC(0) gdi = windll.LoadLibrary("c:\\windows\\system32\\gdi32.dll") while True: FG = w.GetWindowText(w.GetForegroundWindow()) #FG = Foreground window title. if FG == "World of Warcraft": rgb = (PILColorToRGB(gdi.GetPixel(h,X,Y))) #X, Y time.sleep(0.333) #don't check too often. if (rgb[0] >= 130): #While Pixel (X, Y) is Red... #print "%d %d %d" % (rgb[0], rgb[1], rgb[2]) #Debug wsh.SendKeys("{F12}") #Send a key. time.sleep(0.7) #Add some extra down-time if we send the key. else: time.sleep(5) Basically all this code does is read a pixel on the screen, and send a key (F12) if the pixel is red. But when using this code I regularly get some phantom key-code being pressed. The application I'm using this on is obviously world of warcraft, and I have checked that all keybinds are standard keybinds. However randomly it seems I get either an up arrow, or a w pressed, which moves my character forward whenever this code executes (F12 is bound to a macro, unbound from any movement. If I press f12 with a hardware event, it does not exhibit this behavior. What in the world could be going on here?

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• Out of Core Implementation of a Quadtree

  - by Nima

  Hi, I am trying to build a Quadtree data structure(or let's just say a tree) on the secondary memory(Hard Disk). I have a C++ program to do so and I use fopen to create the files. Also, I am using tesseral coding to store each cell in a file named with its corresponding code to store it on the disk in one directory. The problem is that after creating about 1,100 files, fopen just returns NULL and stops creating new files. I can create further files manually in that directory, but using C++ it can not create any further files. I know about max limit of inode on ext3 filesystem which is (from Wikipedia) 32,000 but mine is way less than that, also note that I can create files manually on the disk; just not through fopen. Also, I really appreciate any idea regarding the best way to store a very dynamic quadtree on disk(I need the nodes to be in separate files and the quadtree might have a depth of 50). Using nested directories is one idea, but I think it will slow down the performance because of following the links on the filesystem to access the file. Thanks, Nima

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• Cooperative/Non-preemptive threading avoiding threadlooks?

  - by Wayne

  Any creative ideas to avoid deadlocks on a yield or sleep with cooperative/non-preemptive multitasking without doing an O/S Thread.Sleep(10)? Typically the yield or sleep call will call back into the scheduler to run other tasks. But this can sometime produce deadlocks. Some background: This application has enormous need for speed and, so far, it's extremely fast as compared to other systems in the same industry. One of the speed techniques is cooperative/non-preemptive threading rather then the cost of a context switch from O/S threads. The high level design a priority manager which calls out to tasks depending on priority and processing time. Each task does one "iteration" of work and returns to wait its turn again in the priority queue. The tricky thing with non-preemptive threading is what to do when you want to a particular task to stop in the middle of work and wait for some other event from a different task before continuing. In this case, we have 3 tasks, A B and C where A is a controller that must synchronize the activity of B and C. First, A starts both B and C. Then B yields so C gets invoked. When C yields, A sees they are both inactive, decides it's time for B to run but not time for C yet. Well B is now stuck in a yield that has called C, so it can never run. Sincerely, Wayne

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• How to loop through a boost::mpl::list?

  - by Kyle

  This is as far as I've gotten, #include <boost/mpl/list.hpp> #include <algorithm> namespace mpl = boost::mpl; class RunAround {}; class HopUpAndDown {}; class Sleep {}; template<typename Instructions> int doThis(); template<> int doThis<RunAround>() { /* run run run.. */ return 3; } template<> int doThis<HopUpAndDown>() { /* hop hop hop.. */ return 2; } template<> int doThis<Sleep>() { /* zzz.. */ return -2; } int main() { typedef mpl::list<RunAround, HopUpAndDown, Sleep> acts; // std::for_each(mpl::begin<acts>::type, mpl::end<acts>::type, doThis<????>); return 0; }; How do I complete this? (I don't know if I should be using std::for_each, just a guess based on another answer here)

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• Problem using custom HttpHandler to process requests for both .aspx and non-extension pages in IIS7

  - by Noel

  I am trying to process both ".aspx" and non-extension page requests (i.e. both contact.aspx and /contact/) using a custom HttpHandler in IIS7. My handler works just fine in either one case or the other, but as soon as I try to process both cases, it only works for one. Please see Handlers snippet from my web.config below: If i keep only mapping to "*.aspx" then all .aspx requests are processed correctly, but obviously extensionless requests won't work: <add name="AllPages.ASPX" path="*.aspx" verb="*" type="Test.PageHandlerFactory, Test" preCondition="" /> If i change the mapping to "*" then all extensionless requests are processed correctly, but ".aspx" requests that should still be handled by this handler stop working. Note that i added the StaticFiles entry in order to process files that are on disk like images, css, js, etc. <add name="WebResource" path="WebResource.axd" verb="GET" type="System.Web.Handlers.AssemblyResourceLoader" /> <add name="StaticFiles" verb="GET,HEAD" path="*.*" type="System.Web.StaticFileHandler" resourceType="File" /> <add name="AllPages" path="*" verb="*" type="Test.PageHandlerFactory, Test" preCondition="" /> The crazy thing is that when i load an ".aspx" request (with the 2nd configuration shown) IIS7 gives a 404 not found error. The error also says that the request is processed by the StaticFiles handler. But I made sure to add resourceType="File" to the StaticFileHandler in order to avoid this. According to MS this means the request is only for "physical files on disk". Am i misreading/interpreting the "on disk" part? My .aspx file isn't on disk, that's why i want to use the handler in the first place.

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• Selenium RC: how to capture/handle error?

  - by KenBurnsFan1

  Hi, My test uses Selenium to loop through a CSV list of URLs via an HTTP proxy (working script below). As I watch the script run I can see about 10% of the calls produce "Proxy error: 502" ("Bad_Gateway"); however, the errors are not captured by my catch-all "except Exception" clause -- ie: instead of writing 'error' in the appropriate row of the "output.csv", they get passed to the else clause and produce a short piece of html that starts: "Proxy error: 502 Read from server failed: Unknown error." Also, if I collect all the URLs which returned 502s and re-run the script, they all pass, which leads me to believe that this is a sporadic network path issue. Question: Can the script be made to recognize the the 502 errors, sleep a minute, and then retry the URL instead of moving on to the next URL in the list? The only alternative that I can think of is to apply re.search("Proxy error: 502") after "get_html_source" as a way to catch the bad calls. Then, if the RE matches, put the script to sleep for a minute and then retry 'sel.open(row[0]' on the URL which produced the 502. Any advice would be much appreciated. Thanks! #python 2.6 from selenium import selenium import unittest, time, re, csv, logging class Untitled(unittest.TestCase): def setUp(self): self.verificationErrors = [] self.selenium = selenium("localhost", 4444, "*firefox", "http://baseDomain.com") self.selenium.start() self.selenium.set_timeout("60000") def test_untitled(self): sel = self.selenium spamReader = csv.reader(open('ListOfSubDomains.csv', 'rb')) for row in spamReader: try: sel.open(row[0]) except Exception: ofile = open('output.csv', 'ab') ofile.write("error" + '\n') ofile.close() else: time.sleep(5) html = sel.get_html_source() ofile = open('output.csv', 'ab') ofile.write(html.encode('utf-8') + '\n') ofile.close() def tearDown(self): self.selenium.stop() self.assertEqual([], self.verificationErrors) if __name__ == "__main__": unittest.main()

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• SQL Server Clustered Index: (Physical) Data Page Order

  - by scherand

  I am struggling understanding what a clustered index in SQL Server 2005 is. I read the MSDN article Clustered Index Structures (among other things) but I am still unsure if I understand it correctly. The (main) question is: what happens if I insert a row (with a "low" key) into a table with a clustered index? The above mentioned MSDN article states: The pages in the data chain and the rows in them are ordered on the value of the clustered index key. And Using Clustered Indexes for example states: For example, if a record is added to the table that is close to the beginning of the sequentially ordered list, any records in the table after that record will need to shift to allow the record to be inserted. Does this mean that if I insert a row with a very "low" key into a table that already contains a gazillion rows literally all rows are physically shifted on disk? I cannot believe that. This would take ages, no? Or is it rather (as I suspect) that there are two scenarios depending on how "full" the first data page is. A) If the page has enough free space to accommodate the record it is placed into the existing data page and data might be (physically) reordered within that page. B) If the page does not have enough free space for the record a new data page would be created (anywhere on the disk!) and "linked" to the front of the leaf level of the B-Tree? This would then mean the "physical order" of the data is restricted to the "page level" (i.e. within a data page) but not to the pages residing on consecutive blocks on the physical hard drive. The data pages are then just linked together in the correct order. Or formulated in an alternative way: if SQL Server needs to read the first N rows of a table that has a clustered index it can read data pages sequentially (following the links) but these pages are not (necessarily) block wise in sequence on disk (so the disk head has to move "randomly"). How close am I? :)

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• How do I fork a maximum of 5 child processes of the parent at any one time?

  - by bstullkid

  I have the following code, which I'm trying to only allow a maximum of 5 children to run at a time, but I can't figure out how to decrement the child count when a child exits. struct { char *s1; char *s2; } s[] = { {"one", "oneB"}, {"two", "twoB"}, {"three", "thr4eeB"}, {"asdf", "3th43reeB"}, {"asdfasdf", "thr33eeB"}, {"asdfasdfasdf", "thdfdreeB"}, {"af3c3", "thrasdfeeB"}, {"fec33", "threfdeB"}, {NULL, NULL} }; int main(int argc, char *argv[]) { int i, im5, children = 0; int pid = fork(); for (i = 0; s[i].s2; i++) { im5 = 0; switch (pid) { case -1: { printf("Error\n"); exit(255); } case 0: { printf("%s -> %s\n", s[i].s1, s[i].s2); if (i==5) im5 = 1; printf("%d\n", im5); sleep(i); exit(1); } default: { // Here is where I need to sleep the parent until chilren < 5 // so where do i decrement children so that it gets modified in the parent process? while(children > 5) sleep(1); children++; pid = fork(); } } } return 1; }

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• CPU friendly infinite loop

  - by Adi

  Writing an infinite loop is simple: while(true){ //add whatever break condition here } But this will trash the CPU performance. This execution thread will take as much as possible from CPU's power. What is the best way to lower the impact on CPU? Adding some Thread.Sleep(n) should do the trick, but setting a high timeout value for Sleep() method may indicate an unresponsive application to the operating system. Let's say I need to perform a task each minute or so in a console app. I need to keep Main() running in an "infinite loop" while a timer will fire the event that will do the job. I would like to keep Main() with the lowest impact on CPU. What methods do you suggest. Sleep() can be ok, but as I already mentioned, this might indicate an unresponsive thread to the operating system. LATER EDIT: I want to explain better what I am looking for: I need a console app not Windows service. Console apps can simulate the Windows services on Windows Mobile 6.x systems with Compact Framework. I need a way to keep the app alive as long as the Windows Mobile device is running. We all know that the console app runs as long as its static Main() function runs, so I need a way to prevent Main() function exit. In special situations (like: updating the app), I need to request the app to stop, so I need to infinitely loop and test for some exit condition. For example, this is why Console.ReadLine() is no use for me. There is no exit condition check. Regarding the above, I still want Main() function as resource friendly as possible. Let asside the fingerprint of the function that checks for the exit condition.

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• Servlet requests are executed sequentially for no apparent reason in Glassfish v3

  - by Fabien Benoit

  Hi, I'm using Glassfish 3 Web profile and can't get http workers to execute concurrently requests on a servlet. This is how i observed the problem. I've made a very simple servlet, that writes the current thread name to the standard output and sleep for 10 seconds : protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println(Thread.currentThread().getName()); try { Thread.sleep(10000); // 10 sec } catch (InterruptedException ex) {} } } And when i'm running several simultaneous requests, I clearly see in the logs that the requests are sequentially executed (one trace every 10 seconds). INFO: http-thread-pool-8080-(2) (10 seconds later...) INFO: http-thread-pool-8080-(1) (10 seconds later...) INFO: http-thread-pool-8080-(2) etc. All my GF settings are untouched - it's the out-of-the-box config (the default thread pool is 2 threads min, 5 max if I recall properly). ...I really don't understand why the sleep() block all the others worker threads. Any insight would be greatly appreciated ! Thanks, Fabien

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• loaded resources looks ugly

  - by Xaver

  I have the TreeView class using in my project. I use icons for it.First i load icons so: ImageList^ il = gcnew ImageList(); il->Images->Add(Image::FromFile("DISK.ico")); il->Images->Add(Image::FromFile("FILE.ico")); il->Images->Add(Image::FromFile("FOLDER.ico")); treeView1->ImageList = il; All was good. But i dont like that if i delete my icons from directory of project. there is error in my project. I decide to add icons in .resx file. Now icons loading look so: ImageList^ il = gcnew ImageList(); Resources::ResourceManager^ resourceManager = gcnew Resources::ResourceManager ("FilesSaver.Form1", GetType()->Assembly); Object^ disk = resourceManager->GetObject("DISK"); il->Images->Add(reinterpret_cast<Image^>(disk)); Object^ file = resourceManager->GetObject("FILE"); il->Images->Add(reinterpret_cast<Image^>(file)); Object^ folder = resourceManager->GetObject("FOLDER"); il->Images->Add(reinterpret_cast<Image^>(folder)); treeView1->ImageList = il; And why icons in the TreeView looks ugly (they look lighter and have a big black border). Why did this happen?

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