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• Why are tools like git-svn that allow git to integrate with svn useful? [closed]

  - by Wes

  I have read these related questions: I'm a Subversion geek, why should I consider or not consider Mercurial or Git or any other DVCS? git for personal (one-man) projects. Overkill? ...and I understand why git is useful. What I don't understand is why tools like git-svn that allow git to integrate with svn are useful. When, for example, a team is working with svn, or any other centralised SCM, why would a member of the team opt to use git-svn? Are there any practical advantages for a developer that has to synchronize with a centralized repository?

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• In the days of modern computing, in 'typical business apps' - why does performance matter?

  - by Prog

  This may seem like an odd question to some of you. I'm a hobbyist Java programmer. I have developed several games, an AI program that creates music, another program for painting, and similar stuff. This is to tell you that I have an experience in programming, but not in professional development of business applications. I see a lot of talk on this site about performance. People often debate what would be the most efficient algorithm in C# to perform a task, or why Python is slow and Java is faster, etc. What I'm trying to understand is: why does this matter? There are specific areas of computing where I see why performance matters: games, where tens of thousands of computations are happening every second in a constant-update loop, or low level systems which other programs rely on, such as OSs and VMs, etc. But for the normal, typical high-level business app, why does performance matter? I can understand why it used to matter, decades ago. Computers were much slower and had much less memory, so you had to think carefully about these things. But today, we have so much memory to spare and computers are so fast: does it actually matter if a particular Java algorithm is O(n^2)? Will it actually make a difference for the end users of this typical business app? When you press a GUI button in a typical business app, and behind the scenes it invokes an O(n^2) algorithm, in these days of modern computing - do you actually feel the inefficiency? My question is split in two: In practice, today does performance matter in a typical normal business program? If it does, please give me real-world examples of places in such an application, where performance and optimizations are important.

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• Firewall error when running Pando Media Booster (for League of Legends) in wine

  - by Matt2

  When I'm downloading League of Legends using Pando Media Booster in wine, I get an error when starting it: Connection Error Your system is currently not allowing access to our servers. Check your Firewall and/or security software sttings to allow PMB.exe to run. Reluctantly, I disabled ufw, but to no avail. The terminal displays the following multiple times: fixme:msvcp90:_Locinfo__Locinfo_ctor_cat_cstr (0x33fcf8 1 C) semi-stub fixme:dbghelp:EnumerateLoadedModulesW64 If this happens, bump the number in mod fixme:wininet:InternetAttemptConnect Stub fixme:oleacc:CreateStdAccessibleObject 0x4f00bc -4 {618736e0-3c3d-11cf-810c-00aa00389b71} 0xc252d18 fixme:oleacc:CreateStdAccessibleObject 0x3700c0 -4 {618736e0-3c3d-11cf-810c-00aa00389b71} 0xc252958 fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:uxtheme:BeginBufferedPaint Stub (0x1c28 0xcde880 0 (nil) 0xc2f6fe8) fixme:uxtheme:EndBufferedPaint Stub ((nil) 1) fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:uxtheme:EndBufferedPaint Stub ((nil) 1) fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:InternetAttemptConnect Stub fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:InternetAttemptConnect Stub fixme:wininet:InternetAttemptConnect Stub fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:advapi:RegisterEventSourceW ((null),L"BugSplat"): stub fixme:advapi:ReportEventW (0xcafe4242,0x0001,0x0000,0x00000001,(nil),0x0003,0x00000000,0x33f224,(nil)): stub err:eventlog:ReportEventW L"Pando_Win" err:eventlog:ReportEventW L"Pando" err:eventlog:ReportEventW L"-1" fixme:advapi:DeregisterEventSource (0xcafe4242) stub fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:wininet:CommitUrlCacheEntryInternal entry already in cache - don't know what to do! fixme:advapi:RegisterEventSourceW ((null),L"BugSplat"): stub fixme:advapi:ReportEventW (0xcafe4242,0x0001,0x0000,0x00000001,(nil),0x0003,0x00000000,0x33f224,(nil)): stub err:eventlog:ReportEventW L"Pando_Win" err:eventlog:ReportEventW L"Pando" err:eventlog:ReportEventW L"-1" fixme:advapi:DeregisterEventSource (0xcafe4242) stub Any idea what's going on here? Is there a better place to put this question?

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• Why is C++ often the first language taught in college?

  - by Casey Patton

  My school starts the computer science curriculum with C++ programming courses, meaning this is the first language that many of the students learn. I've seen that many people dislike C++, and I've read a variety of reasons why. It almost seems to be popular opinion that C++ isn't a very good language. I get the impression it's not very liked based on some questions on StackExchange as well as posts such as: http://damienkatz.net/2004/08/why-c-sucks.html http://blogs.kde.org/node/2298 http://blogs.cio.com/esther_schindler/linus_torvalds_why_c_sucks http://www.dacris.com/blog/2010/02/16/why-c-sucks-part-2/ etc. (Note: It is not my opinion that C++ is a bad language. In fact, it's the main language I use. However, the internet as well as some professors have given me the impression that it's not a very widely liked language. In fact, one of my professor constantly rags on C++, yet it's still the starting language at my college!) With that in mind, why is this the first language taught at many schools? What are the reasons for starting a programming curriculum with C++? Note: This question is similar to "Is C++ suitable as a first language", but is a little different since I'm not interested in whether it's suitable, but why it's been chosen.

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• what should a developer know/address to build commercial Android Apps ?

  - by giulio

  Android and mobile development is an exciting area of development. As it is a new discipline, what would be expected of an android developer to build commercially robust applications in terms of skills ? The problem that I and, i think, many other "noobs" into the technology would like to know are the areas of technical skills and the progression to the required advanced topics that goes beyond the the very basics provided by Google. There is a lot of information that's quite useful but its not organised into categories of discipline nor order.

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• How to know the number of pins on my laptop's ram?

  - by Rajat Saxena

  I am thinking about upgrading my laptop's ram.How can I get to know the number of pins on my ram without opening my laptop? I ran this command sudo dmidecode --type memory and got following info: Handle 0x0019, DMI type 17, 27 bytes Memory Device Array Handle: 0x0017 Error Information Handle: 0x001A Total Width: 64 bits Data Width: 64 bits Size: 1024 MB Form Factor: SODIMM Set: None Locator: DIMM0 Bank Locator: BANK 0 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: AD00000000000000 Serial Number: 04008104 Asset Tag: Unknown Part Number: 040404040404040404040404040404040404 Can anyone help?

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• ipconfig /release not working, why?

  - by barlop

  ipconfig /release is not working, why is that? here is a sequence where I put my cable in get an IP, try ipconfig /release and it tells me it can't release wireless, but there is no wireless connection. i'm just trying to release the wired one. C:\>ipconfig Windows IP Configuration Ethernet adapter Wireless Network Connection: Media State . . . . . . . . . . . : Media disconnected Ethernet adapter Local Area Connection: Media State . . . . . . . . . . . : Media disconnected Fine so I plug my cable in C:\>ipconfig Windows IP Configuration Ethernet adapter Wireless Network Connection: Media State . . . . . . . . . . . : Media disconnected Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : IP Address. . . . . . . . . . . . : 0.0.0.0 Subnet Mask . . . . . . . . . . . : 0.0.0.0 Default Gateway . . . . . . . . . : C:\>ipconfig Windows IP Configuration Ethernet adapter Wireless Network Connection: Media State . . . . . . . . . . . : Media disconnected Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : IP Address. . . . . . . . . . . . : 192.168.1.8 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.1.254 Fine so from above, it clearly has an iP C:\>ipconfig /release Windows IP Configuration No operation can be performed on Wireless Network Connection while it has its me dia disconnected. C:\>

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• "Half of everything you know will be obsolete in 18-24 months" = ( True, or False? )

  - by blunders

  Just ran across this, and wondering if anyone has a way to prove or disprove this statement: Something to keep in mind ... what's the half-life of knowledge in high tech? It tracks with Moore's Law: half of everything you know will be obsolete in 18-24 months. SOURCE: Within answer by Craig Trader to this question "What is the single most effective thing you did to improve your programming skills?"

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• Why is domU faster than dom0 on IO?

  - by Paco

  I have installed debian 7 on a physical machine. This is the configuration of the machine: 3 hard drives using RAID 5 Strip element size: 1M Read policy: Adaptive read ahead Write policy: Write Through /boot 200 MB ext2 / 15 GB ext3 SWAP 10GB LVM rest (~500GB) emphasized text I installed postgresql, created a big database (over 1GB). I have an SQL request that takes a lot of time to run (a SELECT statement, so it only reads data from the database). This request takes approximately 5.5 seconds to run. Then, I installed XEN, created a domU, with another debian distro. On this OS, I also installed postgresql, with the same database. The same SQL request takes only 2.5 seconds to run. I checked the kernel on both dom0 and domU. uname-a returns "Linux debian 3.2.0-4-amd64 #1 SMP Debian 3.2.41-2+deb7u2 x86_64 GNU/Linux" on both systems. I checked the kernel parameters, which are approximately the same. For those that are relevant, I changed their values to make them match on both systems using sysctl. I saw no changes (the requests still take the same amount of time). After this, I checked the file systems. I used ext3 on domU. Still no changes. I installed hdparm, and ran hdparm -Tt on both systems, on all my partitions on both systems, and I get similar results. Now, I am stuck, I don't know what is different, and what could be the cause of such a big difference. Additional Info: Debian runs on a Dell server PowerEdge 2950 postgresql: 9.1.9 (both dom0 and domU) xen-linux-system: 3.2.0 xen-hypervisor: 4.1 Thanks EDIT: As Krzysztof Ksiezyk suggested, it might be due to some file caching system. I ran the dd command to test both the read and write speed. Here is domU: root@test1:~# dd if=/dev/zero of=/root/dd count=5MB bs=1MB ^C2020+0 records in 2020+0 records out 2020000000 bytes (2.0 GB) copied, 18.8289 s, 107 MB/s root@test1:~# dd if=/root/dd of=/dev/null count=5MB bs=1MB 2020+0 records in 2020+0 records out 2020000000 bytes (2.0 GB) copied, 15.0549 s, 134 MB/s And here is dom0: root@debian:~# dd if=/dev/zero of=/root/dd count=5MB bs=1MB ^C1693+0 records in 1693+0 records out 1693000000 bytes (1.7 GB) copied, 8.87281 s, 191 MB/s root@debian:~# dd if=/root/dd of=/dev/null count=5MB bs=1MB 1693+0 records in 1693+0 records out 1693000000 bytes (1.7 GB) copied, 0.501509 s, 3.4 GB/s What can be the cause of this caching system? And how can we "fix" it? Can we apply it to dom0? EDIT 2: I switched my virtual disk type. To do so I followed this article. I did a dd if=/dev/vg0/test1-disk of=/mnt/test1-disk.img bs=16M Then in /etc/xen/test1.cfg, I changed the disk parameter to use file: instead of phy: it should have removed the file caching, but I still get the same numbers (domU being much faster for Postgres)

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• Why use C++ when C works for large projects equally well?

  - by Karl

  Before I start, please DO NOT make this into a C vs C++ flamewar. This question has nothing to do with which language is better or not. Period. I have read that C++ is said to be fit for large projects. After all, it makes managing code easier. OO and other features, for example the STL. But then why use C++ when C works equally well for large projects? Take the example of the Linux kernel. Or GNOME. Or even Windows I guess, it is written in C right? So why bother at all with the complexity of C++ (templates and all that), when C works well and this is not just a statement, but proper examples have been quoted. If it works for projects of magnitude of the kernel, why is C++ preferred or why is C not used for almost all projects?

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• Do you know any independant keyword(phrase) statistics trend website?

  - by Sam

  Hi all, does anyone know an equally impressive service that shows the amount of times a specific keyword(phrase) has been searched, as well as a branch of other similar words? The one discussed in this video (Wordtracker.com) seems very good, but has gone commercial unfortunately which is not what Im looking for. I really would prefer free tool... http://www.youtube.com/watch?v=H2M1tXtAc18&feature=related Any suggestions for similar free online tools are very welcome. Thanks

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• Master Data and Data Quality - Do You Really Know Your Customer?

  - by Mala Narasimharajan

  How well do you know your customer?   Data Quality and MDM go hand-in-hand when it comes to fully knowing your customers and information related to the Take a look at this video and see why customer data needs a consolidated management strategy that incorporates data quality.  Oracle MDM, specifically Oracle Customer Hub enables enterprises to truly understand their customers and ensure a single, trusted view for any customer.  It offers the most complete MDM application suite in the marketplace.  For more information on Oracle MDM and Oracle Enterprise Data Quality visit us on the web.  

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• What should I know before getting involved in Kinect development?

  - by chossen-addict

  I'm in the final year of my Computer Science degree, and I'm starting to look at what I can work on as a final-year project. I've been looking at creating a Kinect application, but I'm not sure if I have the necessary background to get involved in its development. What should I know before starting Kinect development? Are there areas of programming I should have a background in in order to understand what I need to do to create a Kinect app?

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• Why isn't passwordless ssh working?

  - by Nelson

  I have two Ubuntu Server machines sitting at home. One is 192.168.1.15 (we'll call this 15), and the other is 192.168.1.25 (we'll call this 25). For some reason, when I want to setup passwordless login from 15 to 25, it works like a champ. When I repeat the steps on 25, so that 25 can login without a password on 15, no dice. I have checked both sshd_config files. Both have: RSAAuthentication yes PubkeyAuthentication yes I have checked permissions on both servers: drwx------ 2 bion2 bion2 4096 Dec 4 12:51 .ssh -rw------- 1 bion2 bion2 398 Dec 4 13:10 authorized_keys On 25. drwx------ 2 shimdidly shimdidly 4096 Dec 4 19:15 .ssh -rw------- 1 shimdidly shimdidly 1018 Dec 4 18:54 authorized_keys On 15. I just don't understand when things would work one way and not the other. I know it's probably something obvious just staring me in the face, but for the life of me, I can't figure out what is going on. Here's what ssh -v says when I try to ssh from 25 to 15: ssh -v -p 51337 192.168.1.15 OpenSSH_5.9p1 Debian-5ubuntu1, OpenSSL 1.0.1 14 Mar 2012 debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 19: Applying options for * debug1: Connecting to 192.168.1.15 [192.168.1.15] port 51337. debug1: Connection established. debug1: identity file /home/shimdidly/.ssh/id_rsa type 1 debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048 debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048 debug1: identity file /home/shimdidly/.ssh/id_rsa-cert type -1 debug1: identity file /home/shimdidly/.ssh/id_dsa type 2 debug1: Checking blacklist file /usr/share/ssh/blacklist.DSA-1024 debug1: Checking blacklist file /etc/ssh/blacklist.DSA-1024 debug1: identity file /home/shimdidly/.ssh/id_dsa-cert type -1 debug1: identity file /home/shimdidly/.ssh/id_ecdsa type -1 debug1: identity file /home/shimdidly/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1 debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ECDSA 54:5c:60:80:74:ab:ab:31:36:a1:d3:9b:db:31:2a:ee debug1: Host '[192.168.1.15]:51337' is known and matches the ECDSA host key. debug1: Found key in /home/shimdidly/.ssh/known_hosts:2 debug1: ssh_ecdsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/shimdidly/.ssh/id_rsa debug1: Authentications that can continue: publickey,password debug1: Offering DSA public key: /home/shimdidly/.ssh/id_dsa debug1: Authentications that can continue: publickey,password debug1: Trying private key: /home/shimdidly/.ssh/id_ecdsa debug1: Next authentication method: password

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• What it is that will completely change the scene as we know it today?

  - by Eyewan

  Have you ever thought about what it is that it might be next in programming and IT industries that will completely change the scene as we know it today. Do you ever pause and think of something like that, what could it be? I think that it is really important for developers to have the awareness about such thing. That is what drives us to continually learn and improve ourselves, always something new awaits us just around the corner and everything is going to change in blink of an eye.

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• Why are there so many minus pont on questions in this forum? [migrated]

  - by BlackLotus

  First, I think I will get minus too here or blocked idk why I want know this so why when I am looking at question list so many minus point on question here so they are asking about programming not other, so this programmers forum or not? and what defferent with stackoverflow ? so many question about programmer there but just little question got minus and i know that must got minus because asking about cyber cryme or other bad but here so many good question got minus why ? thanks for replay,good or not

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• Why "./" is used to run ".sh" scripts in Unix? [duplicate]

  - by user283502

  This question already has an answer here: Why do I need to type `./` before executing a program in the current directory? 10 answers I am executing a .sh script today. It is executed with prefix "./.sh,I am a bit confuse because it is also executed without ./.but why this is required to use ./ Could you please explain me that why ./ is used to run .sh scripts?

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• Why wireless adatper stop to work?

  - by AndreaNobili

  today I correctly installed the driver for the TP-LINK TL-WN725N USB wireless adapter on my RaspBerry Pi (I use RaspBian that is a Debian), then I setted up the wifi using the wpa-supplicant as explained in this tutorial: http://www.maketecheasier.com/setup-wifi-on-raspberry-pi/ This worked fine untill this evening. Then suddenly it stopped to work when I try to connect in SSH and the Raspberry is on the wireless (or rather it should be, as this is not in the list of my router's DHCP connected Client) The strange thing is that the USB wirless adapter blink so I think that this is not a driver problem. If I try to connect it by the ethernet I have no problem. It appear in my router's DHCP connected Client and I can connect to it by SSH. When I connect to it using ethernet if I perform an ifconfig command I obtain: pi@raspberrypi ~ $ ifconfig eth0 Link encap:Ethernet HWaddr b8:27:eb:2a:9f:b0 inet addr:192.168.1.9 Bcast:192.168.1.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:48 errors:0 dropped:0 overruns:0 frame:0 TX packets:59 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:6006 (5.8 KiB) TX bytes:8268 (8.0 KiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:8 errors:0 dropped:0 overruns:0 frame:0 TX packets:8 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1104 (1.0 KiB) TX bytes:1104 (1.0 KiB) wlan0 Link encap:Ethernet HWaddr e8:94:f6:19:80:4c UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) So it seems that the wlan0 USB wireless adapter driver is correctly loaded. If I remove the USB wireless adapter and put it again into the USB port, the lasts lines of dmesg log is: [ 20.303172] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup [ 20.306340] RTL871X: set bssid:00:00:00:00:00:00 [ 20.306726] RTL871X: set ssid [g\xffffffc6isQ\xffffffffJ\xffffffec)\xffffffcd\xffffffba\xffffffba\xffffffab\xfffffff2\xfffffffb\xffffffe3F|\xffffffc2T\xfffffff8\x1b\xffffffe8\xffffffe7\xffffff8dvZ.c3\xffffff9f\xffffffc9\xffffff9a\xffffff9aD\xffffffa7\x1a\xffffffa0\x1a\xffffff8b] fw_state=0x00000008 [ 21.614585] RTL871X: indicate disassoc [ 21.908495] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1 [ 25.006282] Adding 102396k swap on /var/swap. Priority:-1 extents:1 across:102396k SSFS [ 26.247997] RTL871X: nolinked power save enter As you can see some of these line are related to the RTL871X that is my USB wireless adapter, but I don't know is that these line report an error or if it is all ok. Looking at the adapter status I obtain: pi@raspberrypi ~ $ ip link list dev wlan0 3: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DORMANT qlen 1000 link/ether e8:94:f6:19:80:4c brd ff:ff:ff:ff:ff:ff As you can see the mode is DORMANT but I think that this is normal because now I am connected using ethernet. I tryied to set up the adapter but it seems that I obtain no result, infact: pi@raspberrypi ~ $ sudo ip link set dev wlan0 up pi@raspberrypi ~ $ ip link list dev wlan0 3: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DORMANT qlen 1000 link/ether e8:94:f6:19:80:4c brd ff:ff:ff:ff:ff:ff pi@raspberrypi ~ $ sudo ip link set dev wlan0 up This is my /etc/network/interfaces file content and it is ok: auto lo iface lo inet loopback iface eth0 inet dhcp allow-hotplug wlan0 iface wlan0 inet manual wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf iface default inet dhcp and it is the /etc/wpa_supplicant/wpa_supplicant.conf that I think is ok (I did not change it compared to when it worked): ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev update_config=1 network={ ssid="MY-NETWORK" psk="mypassword" key_mgmt=WPA-PSK } and infact if I execute a network scan I correctly find MY-NETWORK in the network list,infact: pi@raspberrypi ~ $ sudo iwlist wlan0 scan | grep ESSID ESSID:"TeleTu_74888B0060AD" ESSID:"MY-NETWORK" ESSID:"FASTWEB-1-PT6NtjL4TOSe" ESSID:"DC" So I reboot the system and I remove the ethernet cable but when I try to connect again to my raspberry I obatin the following error message: andrea@andrea-virtual-machine:~$ sudo ssh [email protected] ssh: connect to host 192.168.1.9 port 22: No route to host It seems that it can't connect using wireless. What could be the problem? What am I missing? How can I solve this situation? Tnx

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• SNTP, why do you mock me?!

  - by Matthew

  --- SOLVED SEE EDIT 5 --- My w2k3 pdc is configured as an authoritative time server. Other servers on the domain are able to sync with it if I manually specify it in the peer list. By if I try to sync from flags 'domhier', it wont resync; I get the error message The computer did not resync because no time data was available. I can only think that it is not querying the pdc. I also tried setting the registry as shown here (http://support.microsoft.com/kb/193825). But no luck (I have not restarted the server, I am hoping I wont have to since it is the pdc) If you would like any further information on my config, please let me know. Edit 1: I have set the w32time service config AnnouceFlags to 0x05 as documented here www.krr.org/microsoft/authoritative_time_servers.php and a number of other places. The PDC syncs to an external time source (ntp). I can get the stripchart on the client from the pdc no problems. The loginserver for the host I am trying to configure is shown as the pdc. Edit 2: The packet capture has revealed something interesting. The client is contacting the correct server, and getting a valid response but I still get the same error message. Here is the NTP excerpt from the client to the server Flags: 11.. .... = Leap Indicator: alarm condition (clock not synchronized) (3) ..01 1... = Version number: NTP Version 3 (3) .... .011 = Mode: client (3) Peer Clock Stratum: unspecified or unavailable (0) Peer Polling Interval: 10 (1024 sec) Peer Clock Precision: 0.015625 sec Root Delay: 0.0000 sec Root Dispersion: 1.0156 sec Reference Clock ID: NULL Reference Clock Update Time: Sep 1, 2010 05:29:39.8170 UTC Originate Time Stamp: NULL Receive Time Stamp: NULL Transmit Time Stamp: Nov 8, 2010 01:44:44.1450 UTC Key ID: DC080000 Here is the reply NTP excerpt from the server to the client Flags: 0x1c 00.. .... = Leap Indicator: no warning (0) ..01 1... = Version number: NTP Version 3 (3) .... .100 = Mode: server (4) Peer Clock Stratum: secondary reference (3) Peer Polling Interval: 10 (1024 sec) Peer Clock Precision: 0.00001 sec Root Delay: 0.1484 sec Root Dispersion: 0.1060 sec Reference Clock ID: 192.189.54.17 Reference Clock Update Time: Nov 8,2010 01:18:04.6223 UTC Originate Time Stamp: Nov 8, 2010 01:44:44.1450 UTC Receive Time Stamp: Nov 8, 2010 01:46:44.1975 UTC Transmit Time Stamp: Nov 8, 2010 01:46:44.1975 UTC Key ID: 00000000 Edit 3: dumpreg for paramters on pdc Value Name Value Type Value Data ------------------------------------------------------------------------ ServiceMain REG_SZ SvchostEntry_W32Time ServiceDll REG_EXPAND_SZ C:\WINDOWS\system32\w32time.dll NtpServer REG_SZ bhvmmgt01.domain.com,0x1 Type REG_SZ AllSync and config Value Name Value Type Value Data -------------------------------------------------------------------------- LastClockRate REG_DWORD 156249 MinClockRate REG_DWORD 155860 MaxClockRate REG_DWORD 156640 FrequencyCorrectRate REG_DWORD 4 PollAdjustFactor REG_DWORD 5 LargePhaseOffset REG_DWORD 50000000 SpikeWatchPeriod REG_DWORD 900 HoldPeriod REG_DWORD 5 LocalClockDispersion REG_DWORD 10 EventLogFlags REG_DWORD 2 PhaseCorrectRate REG_DWORD 7 MinPollInterval REG_DWORD 6 MaxPollInterval REG_DWORD 10 UpdateInterval REG_DWORD 100 MaxNegPhaseCorrection REG_DWORD -1 MaxPosPhaseCorrection REG_DWORD -1 AnnounceFlags REG_DWORD 5 MaxAllowedPhaseOffset REG_DWORD 300 FileLogSize REG_DWORD 10000000 FileLogName REG_SZ C:\Windows\Temp\w32time.log FileLogEntries REG_SZ 0-300 Edit 4: Here are some notables from the ntp log file on the pdc. ReadConfig: failed. Use default one 'TimeJumpAuditOffset'=0x00007080 DomainHierachy: we are now the domain root. ClockDispln: we're a reliable time service with no time source: LS: 0, TN: 864000000000, WAIT: 86400000 Edit 5: F&^%ING SOLVED! Ok so I was reading about people with similar problems, some mentioned w32time server settings applied by GPO, but I tested this early on and there were no settings applied to this service by gpo. Others said that the reporting software may not be picking up some old gpo settings applied. So I searched the registry for all w32time instaces. I came across an interesting key that indicated there may be some other ntp software running on the server. Sure enough, I look through the installed software list and there the little F*&%ER is. Uninstalled and now working like a dream. FFFFFFFUUUUUUUUUUUU

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• Why are USB 2.0 devices crashing my system?

  - by BenAlabaster

  Background on the machine I'm having a problem with: The machine was inherited and appears to be circa 2003 (there's a date stamp on the power supply which leads me to this conclusion). I've got it set up as a Skype terminal for my 2 year old to keep in touch with her grandparents and other members of the family - which everyone loves. It has a generic baby-ATX motherboard with no identifying markings. CPU-Z identifies the motherboard model as VT8601 but doesn't provide me with any manufacturer name. There's one stamp on the motherboard that says "Rev.B". On board it has 10/100 LAN, 2 x USB 1.0, VGA, PS/2 for KB and mouse, parallel port, 2 x serial ports, 2 x IDE, 1 x floppy, 2 x SDRAM slots, 1 x CPU housing that is seating a 1.3GHz Intel Celeron CPU, 3 x PCI, 1 x AGP - although you can only use 2 of the PCI slots if you use the AGP slot due to the physical layout of the board. It's got 768Mb PC133 SDRAM - 1 x 512Mb & 1 x 256Mb installed as well as a D-LINK WDA-2320 54G Wi-Fi network card and a generic USB 2.0 expansion board containing 3 x external + 1 x internal USB connectors. All this is sitting in a slimline case. I don't know the wattage of the PSU, but can post this later if this proves to be helpful. The motherboard is running a version of Award BIOS for which I don't have the version number to hand but can again post this later if it would be helpful. It has an 80Gb Western Digital hard drive freshly formatted and built with Windows XP Professional with Service Pack 3 and all current patches. In addition to Windows XP, the only other software it's running is Skype 4.1 (4.2 crashes the machine as soon as it starts up). It's got a Daytek MV150 15" touch screen running through the VGA and COM1 with the most current drivers from the Daytek website and the most current version of ELO-Touchsystems drivers for the touch component. The webcam is a Logitech Webcam C200 with the latest drivers from the Logitech website. The problem If I hook any USB 2.0 devices to this machine, it hangs the whole machine and I have to hard boot it to get it back up. Workarounds found I can plug the same devices into the on board USB 1.0 connectors and everything works fine, albeit at reduced performance. I've tried 3 different kinds of USB thumb drives, 3 different makes/models of webcams and my iPhone all with the same effect. They're recognized and don't hang the machine when I hook them to the USB 1.0 but if I hook them to the USB 2.0 ports, the machine hangs within a couple of seconds of recognizing the devices were connected. Attempted solutions I've tried disabling all the on board devices that I'm not using - such as the on board LAN, the second COM port, the AGP connector etc. through the BIOS in an (perhaps misguided or futile) attempt to reduce the power consumption... I don't think it had any effect but it didn't do any harm. I was wondering if the PSU wattage just isn't enough to drive the USB 2.0 devices; I've seen this suggested but haven't found any confirmation that this could really be an issue - nor have I found a way to work around this issue - if indeed it is one. Any ideas? The only thing I haven't done which I only just thought of while writing this essay is trying the USB 2.0 card in a different PCI slot, or re-ordering the wi-fi and USB cards in the slots... although I'm not sure if this will make any difference. I've installed the USB card in another machine and it works without issue, so it's not a problem with the USB card itself. Other thoughts Perhaps this is an incompatibility between the USB 2.0 card and the BIOS, would re-flashing the BIOS with a newer version help? Do I need to be able to identify the manufacturer of the motherboard in order to be able to find a BIOS edition specific for this motherboard or will any version of Award BIOS function in its place? Question Does anyone have any ideas that could help me get my USB 2.0 devices hooked up to this machine?

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• Why my VPN doesn't work anymore?

  - by xx77aBs

  I have openvpn server running on debian lenny. There is only one client - and it is running Windows 7 64-bit. This has worked for few months without any problems. And now, let's say for the last 7 days, it doesn't work at all. I connect successfully from client to the server, but I can't access anything through VPN. I have set it up so that all internet traffic is routed through VPN, and now when I connect with the client, the client can't do anything on the net (open any webpage, ping google, anything ...). Can you help me to figure out what's wrong ? I don't know where to start. I've also tried to connect to another openvpn server (I've installed and configured openvpn on another server, and when I try to connect to it result is the same). So I think there's something wrong with client ... Here is my connection log: Wed Apr 04 21:35:59 2012 OpenVPN 2.3-alpha1 Win32-MSVC++ [SSL (OpenSSL)] [LZO2] [PF_INET6] [IPv6 payload 20110522-1 (2.2.0)] built on Feb 21 2012 Enter Management Password: Wed Apr 04 21:35:59 2012 MANAGEMENT: TCP Socket listening on [AF_INET]127.0.0.10:25340 Wed Apr 04 21:35:59 2012 Need hold release from management interface, waiting... Wed Apr 04 21:36:00 2012 MANAGEMENT: Client connected from [AF_INET]127.0.0.10:25340 Wed Apr 04 21:36:00 2012 MANAGEMENT: CMD 'state on' Wed Apr 04 21:36:00 2012 MANAGEMENT: CMD 'log all on' Wed Apr 04 21:36:00 2012 MANAGEMENT: CMD 'hold off' Wed Apr 04 21:36:00 2012 MANAGEMENT: CMD 'hold release' Wed Apr 04 21:36:00 2012 WARNING: No server certificate verification method has been enabled. See http://openvpn.net/howto.html#mitm for more info. Wed Apr 04 21:36:00 2012 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables Wed Apr 04 21:36:00 2012 Socket Buffers: R=[8192->8192] S=[8192->8192] Wed Apr 04 21:36:00 2012 MANAGEMENT: >STATE:1333568160,RESOLVE,,, Wed Apr 04 21:36:00 2012 UDPv4 link local: [undef] Wed Apr 04 21:36:00 2012 UDPv4 link remote: [AF_INET]11.22.33.44:1234 Wed Apr 04 21:36:00 2012 MANAGEMENT: >STATE:1333568160,WAIT,,, Wed Apr 04 21:36:00 2012 MANAGEMENT: >STATE:1333568160,AUTH,,, Wed Apr 04 21:36:00 2012 TLS: Initial packet from [AF_INET]11.22.33.44:1234, sid=ee329574 f15e9e04 Wed Apr 04 21:36:00 2012 VERIFY OK: depth=1, C=US, ST=CA, L=SanFrancisco, O=Fort-Funston, CN=Fort-Funston CA, [email protected] Wed Apr 04 21:36:00 2012 VERIFY OK: depth=0, C=US, ST=CA, L=SanFrancisco, O=Fort-Funston, CN=server_key, [email protected] Wed Apr 04 21:36:01 2012 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key Wed Apr 04 21:36:01 2012 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Wed Apr 04 21:36:01 2012 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key Wed Apr 04 21:36:01 2012 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Wed Apr 04 21:36:01 2012 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA Wed Apr 04 21:36:01 2012 [server_key] Peer Connection Initiated with [AF_INET]11.22.33.44:1234 Wed Apr 04 21:36:02 2012 MANAGEMENT: >STATE:1333568162,GET_CONFIG,,, Wed Apr 04 21:36:03 2012 SENT CONTROL [server_key]: 'PUSH_REQUEST' (status=1) Wed Apr 04 21:36:03 2012 PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1,route 172.16.100.1,topology net30,ping 10,ping-restart 120,ifconfig 172.16.100.6 172.16.100.5' Wed Apr 04 21:36:03 2012 OPTIONS IMPORT: timers and/or timeouts modified Wed Apr 04 21:36:03 2012 OPTIONS IMPORT: --ifconfig/up options modified Wed Apr 04 21:36:03 2012 OPTIONS IMPORT: route options modified Wed Apr 04 21:36:03 2012 ROUTE_GATEWAY 192.168.1.1/255.255.255.0 I=15 HWADDR=00:1f:1f:3f:61:55 Wed Apr 04 21:36:03 2012 do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0 Wed Apr 04 21:36:03 2012 MANAGEMENT: >STATE:1333568163,ASSIGN_IP,,172.16.100.6, Wed Apr 04 21:36:03 2012 open_tun, tt->ipv6=0 Wed Apr 04 21:36:03 2012 TAP-WIN32 device [VPN] opened: \\.\Global\{E28FD52B-F6C3-4094-A36A-30CB02FAC7E8}.tap Wed Apr 04 21:36:03 2012 TAP-Win32 Driver Version 9.9 Wed Apr 04 21:36:03 2012 Notified TAP-Win32 driver to set a DHCP IP/netmask of 172.16.100.6/255.255.255.252 on interface {E28FD52B-F6C3-4094-A36A-30CB02FAC7E8} [DHCP-serv: 172.16.100.5, lease-time: 31536000] Wed Apr 04 21:36:03 2012 Successful ARP Flush on interface [31] {E28FD52B-F6C3-4094-A36A-30CB02FAC7E8} Wed Apr 04 21:36:08 2012 TEST ROUTES: 2/2 succeeded len=1 ret=1 a=0 u/d=up Wed Apr 04 21:36:08 2012 C:\Windows\system32\route.exe ADD 11.22.33.44 MASK 255.255.255.255 192.168.1.1 Wed Apr 04 21:36:08 2012 ROUTE: CreateIpForwardEntry succeeded with dwForwardMetric1=25 and dwForwardType=4 Wed Apr 04 21:36:08 2012 Route addition via IPAPI succeeded [adaptive] Wed Apr 04 21:36:08 2012 C:\Windows\system32\route.exe ADD 0.0.0.0 MASK 128.0.0.0 172.16.100.5 Wed Apr 04 21:36:08 2012 ROUTE: CreateIpForwardEntry succeeded with dwForwardMetric1=30 and dwForwardType=4 Wed Apr 04 21:36:08 2012 Route addition via IPAPI succeeded [adaptive] Wed Apr 04 21:36:08 2012 C:\Windows\system32\route.exe ADD 128.0.0.0 MASK 128.0.0.0 172.16.100.5 Wed Apr 04 21:36:08 2012 ROUTE: CreateIpForwardEntry succeeded with dwForwardMetric1=30 and dwForwardType=4 Wed Apr 04 21:36:08 2012 Route addition via IPAPI succeeded [adaptive] Wed Apr 04 21:36:08 2012 MANAGEMENT: >STATE:1333568168,ADD_ROUTES,,, Wed Apr 04 21:36:08 2012 C:\Windows\system32\route.exe ADD 172.16.100.1 MASK 255.255.255.255 172.16.100.5 Wed Apr 04 21:36:08 2012 ROUTE: CreateIpForwardEntry succeeded with dwForwardMetric1=30 and dwForwardType=4 Wed Apr 04 21:36:08 2012 Route addition via IPAPI succeeded [adaptive] Wed Apr 04 21:36:08 2012 Initialization Sequence Completed Wed Apr 04 21:36:08 2012 MANAGEMENT: >STATE:1333568168,CONNECTED,SUCCESS,172.16.100.6,11.22.33.44 Client's route table after connection with OpenVPN: IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.41 281 0.0.0.0 128.0.0.0 172.16.100.1 172.16.100.6 31 94.23.53.45 255.255.255.255 192.168.1.1 192.168.1.41 25 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306 128.0.0.0 128.0.0.0 172.16.100.1 172.16.100.6 31 172.16.100.4 255.255.255.252 On-link 172.16.100.6 286 172.16.100.6 255.255.255.255 On-link 172.16.100.6 286 172.16.100.7 255.255.255.255 On-link 172.16.100.6 286 192.168.1.0 255.255.255.0 On-link 192.168.1.41 281 192.168.1.41 255.255.255.255 On-link 192.168.1.41 281 192.168.1.255 255.255.255.255 On-link 192.168.1.41 281 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 192.168.1.41 281 224.0.0.0 240.0.0.0 On-link 172.16.100.6 286 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306 255.255.255.255 255.255.255.255 On-link 192.168.1.41 281 255.255.255.255 255.255.255.255 On-link 172.16.100.6 286 =========================================================================== Persistent Routes: Network Address Netmask Gateway Address Metric 0.0.0.0 0.0.0.0 192.168.1.1 Default =========================================================================== IPv6 Route Table =========================================================================== Active Routes: If Metric Network Destination Gateway 13 58 ::/0 On-link 1 306 ::1/128 On-link 13 58 2001::/32 On-link 13 306 2001:0:5ef5:79fd:3cc3:6b9:ac7c:14db/128 On-link 15 281 fe80::/64 On-link 31 286 fe80::/64 On-link 13 306 fe80::/64 On-link 13 306 fe80::3cc3:6b9:ac7c:14db/128 On-link 31 286 fe80::7d72:9515:7213:35e3/128 On-link 15 281 fe80::9cec:ce3f:89de:a123/128 On-link 1 306 ff00::/8 On-link 13 306 ff00::/8 On-link 15 281 ff00::/8 On-link 31 286 ff00::/8 On-link =========================================================================== Persistent Routes: None

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• Why are my hard drives failing?

  - by WishCow

  I have a small Ubuntu server running at home, with 2 HDDs. There are two software raids (raid1) on the disks, managed by mdadm, which I believe is irrelevant, but mentioning it anyway. Both of the HDDs are Western Digital, and have been used for around 2 years, when one of them started making clicking noises, and died. I figured that maybe it's natural after 2 years, so I bought a new one, and resynced the raid arrays. After about a month, the other drive also died. I didn't get suspicious, since both drives have been bought at the same time, it's not that surprising to see both of them near each other, so I bought another one. So far, 2 old drives failed, and 2 brand new in the system. After one month, one of the new drives died. This is when it started getting suspicious. Since the PC was put together from some really old parts (think AthlonXP), I figured that maybe the motherboard's SATA controller is the culprit. Of course you can't switch parts easily in an old PC like this, so I bought a whole system, new MB, new CPU, new RAM. Took the just failed drive back, since it was under warranty, and got it replaced. So it is up to 2 failed drives from the old ones, and 1 failed drive from the new ones. No problems, for 1 month. After that errors were creeping up again in /var/log/messages, and mdadm was reporting raid array failures. I started tearing my hair out. Everything is new in the system, it's up to the third brand new HDD, it's simply not possible that all of the new drives that I bought were faulty. Let's see what is still common... the cables. Okay, long shot, let's replace the SATA cables. Take HDD back, smile to the guy at the counter and say that I'm really unlucky. He replaces the HDD. I come home, one month passes and one of HDDs fails, again. I'm not joking. Two of the brand new HDDs have failed. Maybe it's a bug in the OS. Let's see what the manufacturer's testing tool says. Download testing tool, burn it to a CD, reboot, leave HDD testing overnight. Test says that the drive is faulty, and I should back up everything, if I still can. I don't know what's happening, but it does not look like a software problem, something is definitely thrashing the HDDs. I should mention now, that the whole system is in a shoebox. Since there are a load of "build your own ikea case" stuff, I thought there shouldn't be any problems throwing the thing in a box, and stuffing it away somewhere. The box is well ventilated, but I thought that just maybe the drives were overheating. There is no other possible answer to this. So I took the HDD back, and got it replaced (for the 3rd time), and bought HDD coolers. And just now, I have heard the sound of doom. click click whizzzzzzzzz. SSH into the box: You have new mail! mail r 1 DegradedArrayEvent on /dev/md0 ... dmesg output: [47128.000051] ata3: lost interrupt (Status 0x50) [47128.000097] end_request: I/O error, dev sda, sector 58588863 [47128.000134] md: super_written gets error=-5, uptodate=0 [48043.976054] ata3: lost interrupt (Status 0x50) [48043.976086] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [48043.976132] ata3.00: cmd c8/00:18:bf:40:52/00:00:00:00:00/e1 tag 0 dma 12288 in [48043.976135] res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) [48043.976208] ata3.00: status: { DRDY } [48043.976241] ata3: soft resetting link [48044.148446] ata3.00: configured for UDMA/133 [48044.148457] ata3.00: device reported invalid CHS sector 0 [48044.148477] ata3: EH complete Recap: No possibility of overheating 6 drives have failed, 4 of those have been brand new. I'm not sure now that the original two have been faulty, or suffered the same thing that the new ones. There is nothing common in the system, apart from the OS which is Ubuntu Karmic now (started with Jaunty). New MB, new CPU, new RAM, new SATA cables. No, the little holes on the HDD are not covered I'm crying. Really. I don't have the face to return to the store now, it's not possible for 4 drives to fail under 4 months. A few ideas that I have been thinking: Is it possible that I fuck up something when I partition and resync the drives? Can it be so bad that it physicaly wrecks the drive? (since the vendor supplied tool says that the drive is damaged) I do the partitoning with fdisk, and use the same block size for the raid1 partitions (I check the exact block sizes with fdisk -lu) Is it possible that the linux kernel or mdadm, or something is not compatible with this exact brand of HDDs, and thrashes them? Is it possible that it may be the shoebox? Try placing it somewhere else? It's under a shelf now, so humidity is not a problem either. Is it possible that a normal PC case will solve my problem (I'm going to shoot myself then)? I will get a picture tomorrow. Am I just simply cursed? Any help or speculation is greatly appreciated. Edit: The power strip is guarded against overvoltage. Edit2: I have moved inbetween these 4 months, so the possibility of the cause being "dirty" electricity in both places, is very low. Edit3: I have checked the voltages in the BIOS (couldn't borrow a multimeter), and they are all seem correct, the biggest discrepancy is in the 12V, because it's supplying 11.3. Should I be worried about that? Edit4: I put my desktop PC's PSU into the server. The BIOS reported much more accurate voltage readings, and also it has successfully rebuilt the raid1 array, which took some 3-4 hours, so I feel a little positive now. Will get a new PSU tomorrow to test with that. Also, attaching the picture about the box: (disregard the 3rd drive)

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• Why is Varnish not caching?

  - by Justin

  I am troubleshooting the setup of Varnish 3.x on my Ubuntu server. I'm running Drupal 7 on two sites set up on the box, via named-based vhosts. Before trying to get Varnish to play nice with Drupal I'm trying to just get Varnish to a PNG from cache. Here are the headers I get from a curl -I request of the PNG file: HTTP/1.1 200 OK Server: Apache/2.2.22 (Ubuntu) Last-Modified: Sun, 07 Oct 2012 21:18:59 GMT ETag: "a57c2-3850-4cb7ea73db6c0" Accept-Ranges: bytes Content-Length: 14416 Cache-Control: max-age=1209600 Expires: Thu, 25 Oct 2012 22:55:14 GMT Content-Type: image/png Accept-Ranges: bytes Date: Thu, 11 Oct 2012 22:55:14 GMT X-Varnish: 1766703058 Age: 0 Via: 1.1 varnish Connection: keep-alive X-Varnish-Cache: MISS Here is the Varnish VCL file I'm using (It's a default VCL configuration designed for Drupal): # Default backend definition. Set this to point to your content # server. # backend default { .host = "127.0.0.1"; .port = "8080"; } # Respond to incoming requests. sub vcl_recv { # Use anonymous, cached pages if all backends are down. if (!req.backend.healthy) { unset req.http.Cookie; } # Allow the backend to serve up stale content if it is responding slowly. set req.grace = 6h; # Pipe these paths directly to Apache for streaming. #if (req.url ~ "^/admin/content/backup_migrate/export") { # return (pipe); #} # Do not cache these paths. if (req.url ~ "^/status\.php$" || req.url ~ "^/update\.php$" || req.url ~ "^/admin$" || req.url ~ "^/admin/.*$" || req.url ~ "^/flag/.*$" || req.url ~ "^.*/ajax/.*$" || req.url ~ "^.*/ahah/.*$") { return (pass); } # Do not allow outside access to cron.php or install.php. #if (req.url ~ "^/(cron|install)\.php$" && !client.ip ~ internal) { # Have Varnish throw the error directly. # error 404 "Page not found."; # Use a custom error page that you've defined in Drupal at the path "404". # set req.url = "/404"; #} # Always cache the following file types for all users. This list of extensions # appears twice, once here and again in vcl_fetch so make sure you edit both # and keep them equal. if (req.url ~ "(?i)\.(pdf|asc|dat|txt|doc|xls|ppt|tgz|csv|png|gif|jpeg|jpg|ico|swf|css|js)(\?.*)?$") { unset req.http.Cookie; } # Remove all cookies that Drupal doesn't need to know about. We explicitly # list the ones that Drupal does need, the SESS and NO_CACHE. If, after # running this code we find that either of these two cookies remains, we # will pass as the page cannot be cached. if (req.http.Cookie) { # 1. Append a semi-colon to the front of the cookie string. # 2. Remove all spaces that appear after semi-colons. # 3. Match the cookies we want to keep, adding the space we removed # previously back. (\1) is first matching group in the regsuball. # 4. Remove all other cookies, identifying them by the fact that they have # no space after the preceding semi-colon. # 5. Remove all spaces and semi-colons from the beginning and end of the # cookie string. set req.http.Cookie = ";" + req.http.Cookie; set req.http.Cookie = regsuball(req.http.Cookie, "; +", ";"); set req.http.Cookie = regsuball(req.http.Cookie, ";(SESS[a-z0-9]+|SSESS[a-z0-9]+|NO_CACHE)=", "; \1="); set req.http.Cookie = regsuball(req.http.Cookie, ";[^ ][^;]*", ""); set req.http.Cookie = regsuball(req.http.Cookie, "^[; ]+|[; ]+$", ""); if (req.http.Cookie == "") { # If there are no remaining cookies, remove the cookie header. If there # aren't any cookie headers, Varnish's default behavior will be to cache # the page. unset req.http.Cookie; } else { # If there is any cookies left (a session or NO_CACHE cookie), do not # cache the page. Pass it on to Apache directly. return (pass); } } } # Set a header to track a cache HIT/MISS. sub vcl_deliver { if (obj.hits > 0) { set resp.http.X-Varnish-Cache = "HIT"; } else { set resp.http.X-Varnish-Cache = "MISS"; } } # Code determining what to do when serving items from the Apache servers. # beresp == Back-end response from the web server. sub vcl_fetch { # We need this to cache 404s, 301s, 500s. Otherwise, depending on backend but # definitely in Drupal's case these responses are not cacheable by default. if (beresp.status == 404 || beresp.status == 301 || beresp.status == 500) { set beresp.ttl = 10m; } # Don't allow static files to set cookies. # (?i) denotes case insensitive in PCRE (perl compatible regular expressions). # This list of extensions appears twice, once here and again in vcl_recv so # make sure you edit both and keep them equal. if (req.url ~ "(?i)\.(pdf|asc|dat|txt|doc|xls|ppt|tgz|csv|png|gif|jpeg|jpg|ico|swf|css|js)(\?.*)?$") { unset beresp.http.set-cookie; } # Allow items to be stale if needed. set beresp.grace = 6h; } # In the event of an error, show friendlier messages. sub vcl_error { # Redirect to some other URL in the case of a homepage failure. #if (req.url ~ "^/?$") { # set obj.status = 302; # set obj.http.Location = "http://backup.example.com/"; #} # Otherwise redirect to the homepage, which will likely be in the cache. set obj.http.Content-Type = "text/html; charset=utf-8"; synthetic {" <html> <head> <title>Page Unavailable</title> <style> body { background: #303030; text-align: center; color: white; } #page { border: 1px solid #CCC; width: 500px; margin: 100px auto 0; padding: 30px; background: #323232; } a, a:link, a:visited { color: #CCC; } .error { color: #222; } </style> </head> <body onload="setTimeout(function() { window.location = '/' }, 5000)"> <div id="page"> <h1 class="title">Page Unavailable</h1> <p>The page you requested is temporarily unavailable.</p> <p>We're redirecting you to the <a href="/">homepage</a> in 5 seconds.</p> <div class="error">(Error "} + obj.status + " " + obj.response + {")</div> </div> </body> </html> "}; return (deliver); } I'm getting a MISS and age 0 every time. If I'm understanding correctly, this means the file isn't being returned from Varnish's cache. Is there a problem with my Varnish config?

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• Why is it 8 here,understanding buffer overflow

  - by Mask

  void function(int a, int b, int c) { char buffer1[5]; char buffer2[10]; int *ret; ret = buffer1 + 12; (*ret) += 8;//why is it 8?? } void main() { int x; x = 0; function(1,2,3); x = 1; printf("%d\n",x); } The above demo is from here: http://insecure.org/stf/smashstack.html But it's not working here: D:\test>gcc -Wall -Wextra hw.cpp && a.exe hw.cpp: In function `void function(int, int, int)': hw.cpp:6: warning: unused variable 'buffer2' hw.cpp: At global scope: hw.cpp:4: warning: unused parameter 'a' hw.cpp:4: warning: unused parameter 'b' hw.cpp:4: warning: unused parameter 'c' 1 And I don't understand why it's 8 though the author thinks: A little math tells us the distance is 8 bytes.

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• Why allow concatenation of string literals?

  - by Caspin

  I recently got bit by a subtle bug. char ** int2str = { "zero", // 0 "one", // 1 "two" // 2 "three",// 3 nullptr }; assert( values[1] == "one"_s ); // passes assert( values[2] == "two"_s ); // fails If you have godlike code review powers you'll notice I forgot the , after "two". After the considerable effort to find that bug I've got to ask why would anyone ever want this behavior? I can see how this might be useful for macro magic, but then why is this a "feature" in a modern language like python? Have you ever used string literal concatenation in production code?

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