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  • Creating a network link between 2 very close buildings

    - by Daniel Johnson
    I have a charity who have two adjacent medium sized modern detached houses (in the UK): the buildings stand next to each other and are less than 5 metres apart. They have DSL connected to a single computer in one of the buildings. They want to add a network with wireless, and want it to work across both buildings. Being a charity they need to keep costs down. The network would be used for sharing Word documents, e-mail, browsing and skyping. My initial thoughts were to connect the buildings with fibre. So: Option 1 Use fibre between the buildings. Sufficient cable and two TP-LINK MC100CM Fast Ethernet Media Converters. Cost ~£80.00. But there is the extra cost and hassle of running the cable down and up the external walls, lifting and relaying paving, and burying underground. Never having fitted fibre I'm also a little worried about going up the wall and then bending the cable at 90 degrees to go through the wall and into the building. Option 2 Use two TP-Link TL-WA7510N High Powered Outdoor 5Ghz 15dBi Wireless antennas to connect the buildings. There is a clear line of sight at first floor level. Cost ~£100. And much easier to fit than fibre! Is using the TL-WA7510Ns overkill? Is there something more suitable? I had hoped to use some Netgear stuff, e.g. two DGN2200, one in each house and also use them to provide the wireless link between the buildings. However, in bridge mode wireless client association is not available and repeater mode with client association only supports WEP security which isn't strong enough. Is there something similar that would be up to the job? Option 3 Connect the buildings with UTP cable. My concerns here are risk of electric shock due to a difference of potential between the buildings (or are they so close this shouldn't be an issue) and protection from lightning strikes. Is fitting lighting arrestors expensive? And what can be done to ameliorate against the risk of shock? This all falls outside my area of expertise so I would really appreciate some advice.

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  • How to configure DD-WRT routing table when creating an isolated network segment for PCI C VT compliance

    - by tetranz
    I'm the volunteer support and system admin person at a small private school. We need to setup a PCI compliant Windows PC as a virtual terminal for credit card processing. I've read questionnaire SAQ C-VT and, to quote, this computer needs to be accessed: "via a computer that is isolated in a single location, and is not connected to other locations or systems within your environment (this can be achieved via a firewall or network segmentation to isolate the computer from other systems)" Our setup is as follows: DSL modem from ISP is setup to be a "transparent pipe" with no extra services. That goes into the WAN port of Linksys WRT54-GL running a DD-WRT. The LAN is 192.168.1.x. There are a couple of other WRT54-GL / DD-WRT devices. One is used as a wireless AP and another is a client bridge. To isolate the VT (virtual terminal) machine, I have another DD-WRT device. Its WAN is connected to a port on the 192.168.1.x LAN. The virtual terminal machine is connected to its LAN which is at 192.168.10.x. The SPI Firewall etc is turned on. It's basically the default DD-WRT gateway setup where the "ISP" is our own LAN. That's working. All incoming traffic to the VT machine is blocked, including from our own LAN. The VT can access the internet BUT, and here's the problem, it can also ping any of the computers on the 192.168.1.x LAN. I think I need to stop that. I'm guessing that I could do something with the Static Routing table in the VT machine's DD-WRT device. I need to route anything going to 192.168.1.x other than the gateway which is 192.168.1.1 to 0.0.0.0 or something like that. That's where I'm stuck at the end of my knowledge. Or ... do I need to get yet another DD-WRT so the network is "balanced". Maybe I need to have the internet from the DSL going into a DD-WRT which has only two devices on its LAN i.e., two other DD-WRTs, one for the main LAN and one for the VT. I think that would do but I'd like to avoid the extra cost and complexity if I don't need it. Thanks

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  • One user sometimes gets an unknown certificate error opening Outlook

    - by Chris
    Let me clarify a little. This isn't an unknown certificate error it's an unknown certificate error in so much as I can't figure out where the certificate comes from. This happens on a Win 7 Enterprise machine connecting to Exchange 2010 with Outlook 2010. The error he gets is that the root is not trusted because it's a self-signed cert. Take a look at this screenshot because even if I had generated this myself I wouldn't have put "SomeOrganizationalUnit" or "SomeCity" or "SomeState", etc. (Red block covers our domain name.) I'm a little concerned this is a symptom of a security breach. Exchange 2010 has three certificates installed but none of them are this certificate. They all have different expiration dates (one is expired) and different meta-data. edit: There are two scenarios that I see the certificate warning and one of them I can reliably repeat. When the user leaves his computer on over night Outlook pops the Security Warning window. I don't know what time this happens. Using Outlook Anywhere if I connect to Exchange externally via a cellular USB modem the Security Warning window will appear every time I close and reopen Outlook. Whether I say Yes or No does not make a difference on whether or not I can connect to Exchange and send/receive email. In other words, I can always connect to Exchange. I've checked my two Exchange servers and my Cisco router for a certificate that matches this one and I can't find it. edit 2: Here is a screenshot of the Security Alert window. (I've been calling it Security Warning... My mistake.) edit 3: I stopped seeing this error several weeks ago but I can't tie it to any single event (because I just sort of realized that warning had stopped showing up) but I think I found the source of the certificate. Last week I found out that the certificate on our website DomainA.com was invalid. I knew that our web admin had installed a valid certificate so when I look into the problem I found out I was being presented with the invalid certificate that this posting is in regards to. The Exchange server's domain is mail.DomainA.com so I can only guess that Outlook was passing this invalid certificate through as it did some kind of check on DomainA.com. This issue is still a mystery because the certificate warning stopped appearing several weeks ago whereas the invalid certificate issue on the website was only fixed last week. It ended up being a problem with the website control panel. The valid certificate was installed but not being served for some reason and instead the self-signed cert was being served.

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  • How to disable or tune filesystem cache sharing for OpenVZ?

    - by gertvdijk
    For OpenVZ, an example of container-based virtualization, it seems that host and all guests are sharing the filesystem cache. This sounds paradoxical when talking about virtualization, but this is actually a feature of OpenVZ. It makes sense too. Because only one kernel is running, it's possible to benefit from sharing the same pages of filesystem cache in memory. And while it sounds beneficial, I think a set up here actually suffers in performance from it. Here's why I think why: my machines aren't actually sharing any files on disk so I can't benefit from this feature in OpenVZ. Several OpenVZ machines are running MySQL with MyISAM tables. MyISAM relies on the system's filesystem cache for caching of data files, unlike InnoDB's buffer pool. Also some virtual machines are known to do heavy and large I/O operations on the same filesystem in the host. For example, when running cat *.MYD > /dev/null on some large database in one machine, I saw the filesystem cache lowering in another, monitored by htop. This essentially flushes all the useful filesystem cache in guests (FIFO) and so it flushes the MySQL caches in the guests. Now users are complaining that MySQL is very slow. And it is. Some simple SELECT queries take several seconds on times disk I/O is heavily used by other machines. So, simply put: Is there a way to avoid filesystem cache being wiped out by other virtual machines in container-based virtualization? Some thoughts: Choosing algorithm for flushing filesystem cache in the kernel. (possible? how?) Reserving a certain amount of pages for a single VM. (seems no option for filesystem cache type of pages that reading man vzctl) Will running MySQL on another filesystem get me anywhere? If not, I think my alternatives are: Use KVM for MySQL-MyISAM running VMs. KVM actually assigns memory to the VM and does not allow swapping out caches unless using a balloon driver. Move to InnoDB and tune the buffer pools, dirty pages, etc. This is now considered to be 'nice to have' on the long-term as not everyone responsible for administration of the system understands InnoDB. more suggestions welcome. System software: Proxmox (now 1.9, could be upgraded to 2.x). One big LV assigned for the VMs.

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  • Software Raid 10 corrupted superblock after dual disk failure, how do I recover it?

    - by Shoshomiga
    I have a software raid 10 with 6 x 2tb hard drives (raid 1 for /boot), ubuntu 10.04 is the os. I had a raid controller failure that put 2 drives out of sync, crashed the system and initially the os didnt boot up and went into initramfs instead, saying that drives were busy but I eventually managed to bring the raid up by stopping and assembling the drives. The os booted up and said that there were filesystem errors, I chose to ignore because it would remount the fs in read-only mode if there was a problem. Everything seemed to be working fine and the 2 drives started to rebuild, I was sure that it was a sata controller failure because I had dma errors in my log files. The os crashed soon after that with ext errors. Now its not bringing up the raid, it says that there is no superblock on /dev/sda2, even if I assemble manually with all the device names. I also did a memtest and changed the motherboard in addition to everything else. EDIT: This is my partition layout Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x0009c34a Device Boot Start End Blocks Id System /dev/sdb1 * 2048 511999 254976 83 Linux /dev/sdb2 512000 3904980991 1952234496 83 Linux /dev/sdb3 3904980992 3907028991 1024000 82 Linux swap / Solaris All 6 disks have the same layout, partition #1 is for raid 1 /boot, partition #2 is for raid 10 far plan, partition #3 is swap, but sda did not have swap enabled EDIT2: This is the output of mdadm --detail /dev/md1 Layout : near=1, far=2 Chunk Size : 64k UUID : a0feff55:2018f8ff:e368bf24:bd0fce41 Events : 0.3112126 Number Major Minor RaidDevice State 0 8 34 0 spare rebuilding /dev/sdc2 1 0 0 1 removed 2 8 18 2 active sync /dev/sdb2 3 8 50 3 active sync /dev/sdd2 4 0 0 4 removed 5 8 82 5 active sync /dev/sdf2 6 8 66 - spare /dev/sde2 EDIT3: I ran ddrescue and it has copied everything from sda except a single 4096 byte sector that I suspect is the raid superblock EDIT4: Here is some more info too long to fit here lshw: http://pastebin.com/2eKrh7nF mdadm --detail /dev/sd[abcdef]1 (raid1): http://pastebin.com/cgMQWerS mdadm --detail /dev/sd[abcdef]2 (raid10): http://pastebin.com/V5dtcGPF dumpe2fs of /dev/sda2 (from the ddrescue cloned drive): http://pastebin.com/sp0GYcJG I tried to recreate md1 based on this info with the command mdadm --create /dev/md1 -v --assume-clean --level=10 --raid-devices=6 --chunk=64K --layout=f2 /dev/sda2 missing /dev/sdc2 /dev/sdd2 missing /dev/sdf2 But I can't mount it, I also tried to recreate it based on my initial mdadm --detail /dev/md1 but it still doesn't mount It also warns me that /dev/sda2 is an ext2fs file system but I guess its because of ddrescue

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  • Trying to get DNS services running on Windows Server 2008 R2, what am I getting wrong ?

    - by LaserBeak
    Ok, So I am basically trying to get a home server pc up that will provide Domain name services, act as Mail server and web server. I have one static IP, well it's not officially static but hasn't changed in two years so I'll call it static. I have done the following: Configured router NAT/virtual port forward UDP/TCP port 53 to the internal IP of my server 192.168.1.16, in adapter settings specified the manual settings: 192.168.1.16 IP, gateway 192.168.1.1, Subnet: 255.255.255.0 and loopback DNS: 127.0.0.1 Using my public my public IP Checked using http://www.canyouseeme.org/ that port 53 is open and is not being blocked by my ISP. It can see services on this port. Registered Domain name (mydomain.com.au) Updated whois database through the domain registrars site and registered NameServer names: ns0.mydomain.com.au and ns2.mydomain.com.au, both have been associated with my single public IP. (Waited 24 hours) Update the nameserver for mydomain.com.au: primary ns0.mydomain.com.au secondary: ns2.mydomain.com.au (waited 24+ hours) Installed Server 2008 R2, install web server role and DNS role. Webserver works when I enter my public IP into browser of any PC/mobile, get IIS7 welcome page. In DNS server: Created new forward lookup zone: ; ; Database file mydoman.com.au.dns for mydomain.com.au zone. ; Zone version: 10 ; @ IN SOA mydomain.com.au. mydomain.testdomain.com. ( 10 ; serial number 900 ; refresh 600 ; retry 86400 ; expire 3600 ) ; default TTL ; ; Zone NS records ; @ NS ns0.mydomain.com.au. @ NS ns1.mydomain.com.au. ; ; Zone records ; @ A 192.168.1.16 www A 192.168.1.16 The Domain name services will however not work, the whois database updated with ns0.mydomain.com.au etc. but when I type in my site name www.mydomain.com.au from an external machine it will not open site and I can't even ping it (Can't find host) When I check the ns0.mydomain.com.au NS record using a tool Like: http://www.squish.net/dnscheck/ I get: Security: Server ns0.mydomain.com.au (XXX.XXX.XXX.XX <- my public IP) is recursive Domain exists but there is no such record Any ideas, thanks...

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  • understanding my site's DNS records

    - by DaveM
    firstly apologies for using the word 'pointage' this is the word my french domain registrar uses so I may have used to wrong term. OK I would like to better understand what is going on on my 'pointage' record on my domain registrars site. for my (currently empty) web site it reports the following details... Type : Host : Destination A : www.mydomain.org : 62.210.176.146 A : mail.mydomain.org : 84.246.225.176 Mx : .mydomain.org : mail.mydomain.org I think I understand the MX record, that simply relays anything onto the mail.mydomain.org location. However why are the destination for the www and mail domains different. Even more confusing (for me) is the fact that if I ping either of www.mydomain.org or mail.mydomain.org the ping returns a different IP address. This IP address is consistent with that of my server (ie 92.39.247.92). So what exactly is going on ? I'm sure I could find the information on the web,I've read a few thing on the debianhelp site regarding DNS records, and it seems to suggest that the record should be a reverse lookup, but certains isn't the reverse of my servers IP ? but I don't what I should be looking for, so links to docs and search terms for google will be happily accepteed (even though they go against the grain of SO answers to question). thanks in advance. David. ps. I should add that everything seems to work just fine, and I've just descovered this part of the management page of my registrar. Edit: Addition of DNS records and ping results. The DNS record for the site. From what I've read there should only realy be a single 'A' record, so has something gone wrong ? should I change it (remove the extras and then just point www.facilitee.org - .facilitee.org and mail.facilitee.org - .facilitee.org here is the DNS record A www.facilitee.org ? 92.39.247.92 A .facilitee.org ? 92.39.247.92 A mail.facilitee.org ? 92.39.247.92 A webmail.facilitee.org ? 92.39.247.92 MX .facilitee.org ? mail.facilitee.org ping results... ~$ ping www.facilitee.org PING www.facilitee.org (92.39.247.92) 56(84) bytes of data. 64 bytes from vps4576-cloud.dns26.com (92.39.247.92): ~$ ping mail.facilitee.org PING mail.facilitee.org (92.39.247.92) 56(84) bytes of data. 64 bytes from vps4576-cloud.dns26.com (92.39.247.92): So the DNS and the ping correspond, but the 'pointage' doesn't. ~ how can I get a report of the pointage records other than from my registrar ?

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  • A gigabit network interface is CPU-limited to 25MB/s. How can I maximize the throughput?

    - by netvope
    I have a Acer Aspire R1600-U910H with a nForce gigabit network adapter. The maximum TCP throughput of it is about 25MB/s, and apparently it is limited by the single core Intel Atom 230; when the maximum throughput is reached, the CPU usage is about 50%-60%, which corresponds to full utilization considering this is a Hyper-threading enabled CPU. The same problem occurs on both Windows XP and on Ubuntu 8.04. On Windows, I have installed the latest nForce chipset driver, disabled power saving features, and enabled checksum offload. On Linux, the default driver has checksum offload enabled. There is no Linux driver available on Nvidia's website. ethtool -k eth0 shows that checksum offload is enabled: Offload parameters for eth0: rx-checksumming: on tx-checksumming: on scatter-gather: on tcp segmentation offload: on udp fragmentation offload: off generic segmentation offload: off The following is the output of powertop when the network is idle: Wakeups-from-idle per second : 61.9 interval: 10.0s no ACPI power usage estimate available Top causes for wakeups: 90.9% (101.3) <interrupt> : eth0 4.5% ( 5.0) iftop : schedule_timeout (process_timeout) 1.8% ( 2.0) <kernel core> : clocksource_register (clocksource_watchdog) 0.9% ( 1.0) dhcdbd : schedule_timeout (process_timeout) 0.5% ( 0.6) <kernel core> : neigh_table_init_no_netlink (neigh_periodic_timer) And when the maximum throughput of about 25MB/s is reached: Wakeups-from-idle per second : 11175.5 interval: 10.0s no ACPI power usage estimate available Top causes for wakeups: 99.9% (22097.4) <interrupt> : eth0 0.0% ( 5.0) iftop : schedule_timeout (process_timeout) 0.0% ( 2.0) <kernel core> : clocksource_register (clocksource_watchdog) 0.0% ( 1.0) dhcdbd : schedule_timeout (process_timeout) 0.0% ( 0.6) <kernel core> : neigh_table_init_no_netlink (neigh_periodic_timer) Notice the 20000 interrupts per second. Could this be the cause for the high CPU usage and low throughput? If so, how can I improve the situation? As a reference, the other computers in the network can usually transfer at 50+MB/s without problems. A computer with a Core 2 CPU generates only 5000 interrupts per second when it's transferring at 110MB/s. The number of interrupts is about 20 times less than the Atom system (if interrupts scale linearly with throughput.) And a minor question: How can I find out what is the driver in use for eth0?

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  • Squid on windows loadbalancing only to one server

    - by Martin L.
    After thousands of googles and trying days i cant get the load balancer/failover in squid on windows to work. Iam using squid 2.7. My webservers are 2 single NIC lighttpd and one dual nic lighttpd. server1 in this example is running squid on port 80 and lighttpd on port 8080 (just to test) Requirements: All 3 webservers running lighttpd should be balanced two option for load balancing: Best would be if server1 is busy server2 takes over, if server2 is busy server3 takes over, etc.. Round robin style evenly distributed load. Eg server1 takes first call, server2 second etc.. All requests should be treated the same way (no url rewriting or so on) Sent host headers have to be redirected to every server as http host header, speaking of "server1", "server1.company.internal" and "10.211.1.1". My approach: acl all src all acl manager proto cache_object http_port 80 accel defaultsite=server1.company.internal vhost #reverse proxy entries cache_peer 10.211.2.1 parent 8080 0 no-query originserver round-robin login=PASS name=server1_nic1 cache_peer 10.211.1.2 parent 80 0 no-query originserver round-robin login=PASS name=server2_nic1 cache_peer 10.211.2.3 parent 8080 0 no-query originserver round-robin login=PASS name=server3_nic1 cache_peer 10.211.2.4 parent 8080 0 no-query originserver round-robin login=PASS name=server3_nic2 #decl of names of squid host acl registered_name_hostdomain dstdomain server1.company.internal acl registered_name_host dstdomain server1 #ip of squid host acl registered_name_ip dstdomain 10.211.2.1 # access: redirects the correct squid hostname http_access allow registered_name_hostdomain http_access allow registered_name_host http_access allow registered_name_ip http_access deny all cache_peer_access server1_nic1 allow registered_name_hostdomain cache_peer_access server1_nic1 allow registered_name_host cache_peer_access server1_nic1 allow registered_name_ip cache_peer_access server2_nic1 allow registered_name_hostdomain cache_peer_access server2_nic1 allow registered_name_host cache_peer_access server2_nic1 allow registered_name_ip cache_peer_access server3_nic1 allow registered_name_hostdomain cache_peer_access server3_nic1 allow registered_name_host cache_peer_access server3_nic1 allow registered_name_ip cache_peer_access server3_nic2 allow registered_name_hostdomain cache_peer_access server3_nic2 allow registered_name_host cache_peer_access server3_nic2 allow registered_name_ip cache_peer_access server1_nic1 deny all cache_peer_access server2_nic1 deny all cache_peer_access server3_nic1 deny all cache_peer_access server3_nic2 deny all never_direct allow all Problems: Load balancer does not load balance other than to first server. Only if the first server is killed in any way the second will take over. I have seen the others working at some point, but definitely not as the intended load balancing described above. If the cache_peer_access is not defined sometimes the wrong hostname is sent to the backend webserver and this always depends on the defaultsite= parameter. Probably because the host header on the request to squid is not set and its replaced by defaultsite. Leaving out defaultsite didnt solve the problem. The only workaround i found for this is the current approach with cache_peer_access. Questions: Does the cache_peer_access influence the round-robin? Is there a better workaround to pass the host header to the backed webservers? Which parameters do increase the speed of load balancing or does anyone have a better approach? -Martin

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  • Model M Keyboard inputs incorrect characters after logging in to Fedora

    - by mickburkejnr
    I recently bought a 24 year old IBM Model M keyboard. From what I gather, it'd been left on a shelf for the last 5 years, so you can imagine the amount of dust dirt and crap that was on it. Before cleaning it, I plugged it in to my laptop (running Fedora 17) using a PS/2 to USB adapter. What I found was, while it still works, the keys I press don't correspond to what is displayed on the screen. So for example, when I type S on the keyboard, I get ß display on the screen instead. At the time, I put this down to the adapter not working properly. Since then, I stripped the keys off the keyboard and cleaned the whole thing. It looks like it's just come out of a box! I then plugged it in to my computer (also running Fedora 17) via a standard PS/2 plug. The computer loaded up to the login screen, and I typed in my password. Pressed enter, and I logged straight in to my machine. At this point, I opened up a text editor and started typing some stuff. To my horror, the keystrokes I was entering weren't coming up as intended. What came up instead were characters that would map to the pressed key but only under a different keyboard language setting. I opened up a program to see what keyboard language had been selected, and the correct one for the keyboard was selected (which is UK in my case). I opened up a window that would show what characters mapped to what keys, and I pressed every single key on the keyboard, and every corresponding block representing each key lit up. I went back to the text editor to try again, but I was still getting these random characters. Whats more is that the backspace key would not work, although in the other utility it would flash when pressed. What I know is that at the login screen the keyboard must have entered the correct characters, otherwise I wouldn't have been able to log in. Further more, keys that don't respond while using a text editor as sending signals to the computer, as illustrated in that keyboard utility. The question is why random characters are displayed when they really shouldn't be? Would this be a hardware fault or a software issue?

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  • How to tune system settings for mongoDB on Linux?

    - by jsh
    Trying to squeeze a lot out of one question here -- please bear with me. Although the MongoDB man pages make several useful recommendations about system settings like ulimit (http://docs.mongodb.org/manual/reference/ulimit/), and other production factors (http://docs.mongodb.org/manual/administration/production-notes/) they seem mysteriously silent on things like virtual memory and swap settings. The closest we get to a hint is that "...the operating system’s virtual memory subsystem manages MongoDB’s memory..." (http://docs.mongodb.org/manual/faq/fundamentals/#does-mongodb-require-a-lot-of-ram). Running the same job - high writes and high reads on about 10,000,000 records in a single collection -- on my 4-processor, 4GB RAM macbook and an 8-core ubuntu box with 64GB RAM I saw dramatically WORSE read performance on the linux box with factory settings, and could hear the disk constantly spinning, indicating high I/O and presumably swapping. Yes, other things were happening on the box, but there was plenty of free RAM, disk space, etc.; furthermore, I did not see evidence that Mongo was expanding to take advantage of all that free RAM as it is touted to do. Linux box default settings were as follows: vm.swappiness =60 vm.dirty_background_ratio = 10 vm.dirty_ratio = 20 vm.dirty_expire_centisecs =3000 vm.dirty_writeback_centisecs=500 I hazarded some guesses looking at docs and blogs for other types of databases (Oracle, MYSQL, etc.), experimented, and adjusted as below. vm.swappiness=10 vm.dirty_background_ratio=5 vm.dirty_ratio=5 vm.dirty_writeback_centisecs=250 vm.dirty_expire_centisecs=500 I saw some immediate apparent improvements in read time. However, when I ran my test jobs again, read performance continued to be painfully sluggish during heavy writes. Then, I REBUILT the collection from an available data source - and suddenly I can read at 1ms or less per record WHILE doing the write job! So the question is really two-fold: 1) What are appropriate VM settings for MongoDB on Linux? 2) (bonus) Does Mongo do some checking or optimization with the OS while data is being built? In other words, if I have built a large data set with suboptimal VM or I/O settings, does Mongo make assumptions during the memory-mapping process that will fail to take advantage of optimizations down the road? Obviously I don't fully grok memory mapping under the hood (I was hoping I wouldn't have to). Any help appreciated...thanks! -j

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  • Conflicting ip routes with local table on attaching a virtual network interface

    - by user1071840
    I have an EC2 instance with these ip rules: $ sudo ip rule show 0: from all lookup local 32766: from all lookup main 32767: from all lookup default I can attach an elastic network interface to it with a private IP. Say the IP of my machine is 10.1.3.12 and the IP of the interface is 10.1.1.190. As soon as I attach the interface to my machine a new entry is added to the routing policy and local routing table: sudo ip rule show 0: from all lookup local 32765: from 10.1.1.190 lookup 10003 32766: from all lookup main 32767: from all lookup default $ sudo ip route show table local broadcast 10.1.1.0 dev eth3 proto kernel scope link src 10.1.1.190 local 10.1.1.190 dev eth3 proto kernel scope host src 10.1.1.190 broadcast 10.1.1.255 dev eth3 proto kernel scope link src 10.1.1.190 broadcast 10.1.3.0 dev eth0 proto kernel scope link src 10.1.3.12 local 10.1.3.12 dev eth0 proto kernel scope host src 10.1.3.12 broadcast 10.1.3.255 dev eth0 proto kernel scope link src 10.1.3.12 broadcast 127.0.0.0 dev lo proto kernel scope link src 127.0.0.1 local 127.0.0.0/8 dev lo proto kernel scope host src 127.0.0.1 local 127.0.0.1 dev lo proto kernel scope host src 127.0.0.1 broadcast 127.255.255.255 dev lo proto kernel scope link src 127.0.0.1 I can send traffic to this ENI directly from a host that can have the same IP as the host the ENI is attached to. This is where the problem starts. I ran tcpdump on the port in question and saw multiple SYNs going to the ENI with src '10.1.3.12' and destination '10.1.1.190' but didn't see even a single ACK. In my understanding if ACKs were being sent from the ENI they'd have destination as 10.1.3.12 i.e. the same as the local machine's IP and such packets will now be routed as local packets matching local routing policy: local 10.1.3.12 dev eth0 proto kernel scope host src 10.1.3.12 I'd like to send all the packets originating from 10.1.1.190 (my ENI) to go back on the same interface i.e. eth3 in this case. Contents of the nee table 10003 are: $ sudo ip route show table 10003 default via 10.1.1.1 dev eth3 I think I can do the following: I don't know if its possible but probably decrease the priority of local table so the packets match the table 10003. Use iptables to mangle these packets and update the local table route to include the mark information But I'm not sure if these are the right approaches.

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  • Lots of dropped packages when tcpdumping on busy interface

    - by Frands Hansen
    My challenge I need to do tcpdumping of a lot of data - actually from 2 interfaces left in promiscuous mode that are able to see a lot of traffic. To sum it up Log all traffic in promiscuous mode from 2 interfaces Those interfaces are not assigned an IP address pcap files must be rotated per ~1G When 10 TB of files are stored, start truncating the oldest What I currently do Right now I use tcpdump like this: tcpdump -n -C 1000 -z /data/compress.sh -i any -w /data/livedump/capture.pcap $FILTER The $FILTER contains src/dst filters so that I can use -i any. The reason for this is, that I have two interfaces and I would like to run the dump in a single thread rather than two. compress.sh takes care of assigning tar to another CPU core, compress the data, give it a reasonable filename and move it to an archive location. I cannot specify two interfaces, thus I have chosen to use filters and dump from any interface. Right now, I do not do any housekeeping, but I plan on monitoring disk and when I have 100G left I will start wiping the oldest files - this should be fine. And now; my problem I see dropped packets. This is from a dump that has been running for a few hours and collected roughly 250 gigs of pcap files: 430083369 packets captured 430115470 packets received by filter 32057 packets dropped by kernel <-- This is my concern How can I avoid so many packets being dropped? These things I did already try or look at Changed the value of /proc/sys/net/core/rmem_max and /proc/sys/net/core/rmem_default which did indeed help - actually it took care of just around half of the dropped packets. I have also looked at gulp - the problem with gulp is, that it does not support multiple interfaces in one process and it gets angry if the interface does not have an IP address. Unfortunately, that is a deal breaker in my case. Next problem is, that when the traffic flows though a pipe, I cannot get the automatic rotation going. Getting one huge 10 TB file is not very efficient and I don't have a machine with 10TB+ RAM that I can run wireshark on, so that's out. Do you have any suggestions? Maybe even a better way of doing my traffic dump altogether.

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  • MongoDB and datasets that don't fit in RAM no matter how hard you shove

    - by sysadmin1138
    This is very system dependent, but chances are near certain we'll scale past some arbitrary cliff and get into Real Trouble. I'm curious what kind of rules-of-thumb exist for a good RAM to Disk-space ratio. We're planning our next round of systems, and need to make some choices regarding RAM, SSDs, and how much of each the new nodes will get. But now for some performance details! During normal workflow of a single project-run, MongoDB is hit with a very high percentage of writes (70-80%). Once the second stage of the processing pipeline hits, it's extremely high read as it needs to deduplicate records identified in the first half of processing. This is the workflow for which "keep your working set in RAM" is made for, and we're designing around that assumption. The entire dataset is continually hit with random queries from end-user derived sources; though the frequency is irregular, the size is usually pretty small (groups of 10 documents). Since this is user-facing, the replies need to be under the "bored-now" threshold of 3 seconds. This access pattern is much less likely to be in cache, so will be very likely to incur disk hits. A secondary processing workflow is high read of previous processing runs that may be days, weeks, or even months old, and is run infrequently but still needs to be zippy. Up to 100% of the documents in the previous processing run will be accessed. No amount of cache-warming can help with this, I suspect. Finished document sizes vary widely, but the median size is about 8K. The high-read portion of the normal project processing strongly suggests the use of Replicas to help distribute the Read traffic. I have read elsewhere that a 1:10 RAM-GB to HD-GB is a good rule-of-thumb for slow disks, As we are seriously considering using much faster SSDs, I'd like to know if there is a similar rule of thumb for fast disks. I know we're using Mongo in a way where cache-everything really isn't going to fly, which is why I'm looking at ways to engineer a system that can survive such usage. The entire dataset will likely be most of a TB within half a year and keep growing.

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  • Excel 2010: dynamic update of drop down list based upon datasource validation worksheet changes

    - by hornetbzz
    I have one worksheet for setting up the data sources of multiple data validation lists. in other words, I'm using this worksheet to provide drop down lists to multiple other worksheets. I need to dynamically update all worksheets upon any of a single or several changes on the data source worksheet. I may understand this should come with event macro over the entire workbook. My question is how to achieve this keeping the "OFFSET" formula across the whole workbook ? Thx To support my question, I put the piece of code that I'm trying to get it working : Provided the following informations : I'm using such a formula for a pseudo dynamic update of the drop down lists, for example : =OFFSET(MyDataSourceSheet!$O$2;0;0;COUNTA(MyDataSourceSheet!O:O)-1) I looked into the pearson book event chapter but I'm too noob for this. I understand this macro and implemented it successfully as a test with the drop down list on the same worksheet as the data source. My point is that I don't know how to deploy this over a complete workbook. Macro related to the datasource worksheet : Option Explicit Private Sub Worksheet_Change(ByVal Target As Range) ' Macro to update all worksheets with drop down list referenced upon ' this data source worksheet, base on ref names Dim cell As Range Dim isect As Range Dim vOldValue As Variant, vNewValue As Variant Dim dvLists(1 To 6) As String 'data validation area Dim OneValidationListName As Variant dvLists(1) = "mylist1" dvLists(2) = "mylist2" dvLists(3) = "mylist3" dvLists(4) = "mylist4" dvLists(5) = "mylist5" dvLists(6) = "mylist6" On Error GoTo errorHandler For Each OneValidationListName In dvLists 'Set isect = Application.Intersect(Target, ThisWorkbook.Names("STEP").RefersToRange) Set isect = Application.Intersect(Target, ThisWorkbook.Names(OneValidationListName).RefersToRange) ' If a change occured in the source data sheet If Not isect Is Nothing Then ' Prevent infinite loops Application.EnableEvents = False ' Get previous value of this cell With Target vNewValue = .Value Application.Undo vOldValue = .Value .Value = vNewValue End With ' LOCAL dropdown lists : For every cell with validation For Each cell In Me.UsedRange.SpecialCells(xlCellTypeAllValidation) With cell ' If it has list validation AND the validation formula matches AND the value is the old value If .Validation.Type = 3 And .Validation.Formula1 = "=" & OneValidationListName And .Value = vOldValue Then ' Debug ' MsgBox "Address: " & Target.Address ' Change the cell value cell.Value = vNewValue End If End With Next cell ' Call to other worksheets update macros Call Sheets(5).UpdateDropDownList(vOldValue, vNewValue) ' GoTo NowGetOut Application.EnableEvents = True End If Next OneValidationListName NowGetOut: Application.EnableEvents = True Exit Sub errorHandler: MsgBox "Err " & Err.Number & " : " & Err.Description Resume NowGetOut End Sub Macro UpdateDropDownList related to the destination worksheet : Sub UpdateDropDownList(Optional vOldValue As Variant, Optional vNewValue As Variant) ' Debug MsgBox "Received info for update : " & vNewValue ' For every cell with validation For Each cell In Me.UsedRange.SpecialCells(xlCellTypeAllValidation) With cell ' If it has list validation AND the validation formula matches AND the value is the old value ' If .Validation.Type = 3 And .Value = vOldValue Then If .Validation.Type = 3 And .Value = vOldValue Then ' Change the cell value cell.Value = vNewValue End If End With Next cell End Sub

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  • What is the probable failure - no BSOD, no event log, monitors sleeping, force reboot required

    - by Tyler
    Every 3 to 15 days, my PC freezes. This typically happens when the computer is idle, I'm coming home from work, back from vacation, etc. It's never happened while using my computer. The monitors are in power save mode The Caps Lock light on the (wireless) keyboard doesn't work Ctrl-alt-del has no effect, mouse (wireless) has no effect The hardware reset button and single press of power putton have no effect Computer does not appear on the network No BSOD, no memory dump Event logs have no errors or indications of problems near the time of crash. Only messages after reboot indicating that there was a reboot without a clean shutdown. Windows is set to never put the computer to sleep (just the display) Here are the vital stats of the build: OS Windows 8 Pro 64-bit CPU Intel i5-2400 Mobo Intel BOXDP67DE Micro ATX GPU MSI N460GTX Cyclone768D5/OC RAM CORSAIR XMS3 8GB (2 x 4GB) CMX8GX3M2A1333C9 PSU SeaSonic X Series X650 Gold System Drive Samsung 840 Pro 256 GB SSD Data Drive 2 x Western Digital WD20EARS 2TB in hardware RAID 1 Optical Lite-On DVD burner IHAS424-98 And here is the story of how the problem developed and what I've done to diagnose: January 2011, system built with Windows 7 64-bit, runs great. March 2011, Intel replaced the mobo because of the bad sata controllers. October 2012, upgrade to Windows 8 (problems start shortly after). January 2013, system freezes and causes network to fail for the whole house. Unplug the network cable and other devices and PCs can use the internet. Plug it back in, internet goes away for everyone. Reboot and everything is fine. March 2013, install Intel Gigabit CT PCI-E NIC, disable mobo nic in bios. Network strangeness goes away. Freezes are less frequent. Memtest shows no problems (20 passes). Early June 2013, replace Antec PSU with SeaSonic PSU. Mid June 2013, replace OCZ Vertex 2 SSD with Samsung SSD. Late June 2013, get frustrated and hope the community has some good ideas (I'm running out of budget to replace parts). My next plan of attack is setting "Turn off display" to Never and using a screen saver to see how that reacts on the next freeze. It makes me sad to waste power for up to 15 days though. Has anyone out there seen a problem like this? Any ideas on what kind of malfunction would act this way? Ideas of other diagnostic steps to take?

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  • Resetting root password on Fedora Core 3 - serial cable access only

    - by Sensible Eddie
    A little background: We have an old rackmount server running a customised version of Fedora, manufactured by a company called Navaho. The server is a TeamCAT, running some proprietary rubbish called Freedom2. We have to keep it going - the alternative is extraordinarily expensive, and the business is not likely to be running much longer to justify changing things. Through one means or another, it has fallen upon me to try and resolve our lack of root access. The previous admin has fallen under the proverbial bus, and nobody has any clue. We have no access to the root account for this server. ssh is running on the server, and there is one account admin that we can login with, however it has no permission to do anything (ironic...) The only other way into the server is with a null-modem serial cable. This works... up to a point. I can see the BIOS, I can see the post BIOS screen, and then I see "Starting grub", followed by another screen with about four lines of Linux information, but then it stops at that point. The server continues booting, and all services come online after around two minutes, but the serial terminal displays no more information. I understand it is possible to put Linux into "single user mode" to reset a root password, but I have no idea how to do this beyond trying to interrupt it at the grub stage listed above. When I have tried it just froze. It was almost like grub had appeared (since the server did not continue booting) but I couldn't see it on the serial terminal. Which made me think maybe the grub screen has some different serial settings? I don't know... it's the first time I've ever used serial for access! A friend of mine suggested trying to use a Fedora boot CD. We could boot from USB, so something along this approach is possible but again we still can only see what's going on with the serial terminal, so it might not be achievable. Does anyone have any suggestions for things I can try? I appreciate this is a bit of a long shot, but any assistance would be invaluable. *UPDATE 1 - 28/8/12 * - we will be making some attempts on this today and will post further details later!

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  • How should we serve files in a small bioinformatics cluster?

    - by cespinoza
    We have a small cluster of six ubuntu servers. We run bioinformatics analyses on these clusters. Each analysis takes about 24 hours to complete, each core i7 server can handle 2 at a time, takes as input about 5GB data and outputs about 10-25GB of data. We run dozens of these a week. The software is a hodgepodge of custom perl scripts and 3rd party sequence alignment software written in C/C++. Currently, files are served from two of the compute nodes (yes, we're using compute nodes as file servers)-- each node has 5 1TB sata drives mounted separately (no raid) and is pooled via glusterfs 2.0.1. They each have as 3 bonded intel ethernet pci gigabit ethernet cards, attached to a d-link DGS-1224T switch ($300 24 port consumer-level). We are not currently using jumbo frames (not sure why, actually). The two file-serving compute nodes are then mirrored via glusterfs. Each of the four other nodes mounts the files via glusterfs. The files are all large (4gb+), and are stored as bare files (no database/etc) if that matters. As you can imagine, this is a bit of a mess that grew organically without forethought and we want to improve it now that we're running out of space. Our analyses are I/O intensive and it is a bottle neck-- we're only getting 140mB/sec between the two fileservers, maybe 50mb/sec from the clients (which only have single NICs). We have a flexible budget which I can probably get up $5k or so. How should we spend our budget? We need at least 10TB of storage fast enough to serve all nodes. How fast/big does the cpu/memory of such a file server have to be? Should we use NFS, ATA over Ethernet, iSCSI, Glusterfs, or something else? Should we buy two or more servers and create some sort of storage cluster, or is 1 server enough for such a small number of nodes? Should we invest in faster NICs (say, PCI-express cards with multiple connectors)? The switch? Should we use raid, if so, hardware or software? and which raid (5, 6, 10, etc)? Any ideas appreciated. We're biologists, not IT gurus.

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  • How to auto advance a PowerPoint slide after an exit animation is over?

    - by joooc
    PowerPoint entrance animation set up with "Start: With Previous" starts right when a new slide is advanced. However, if you set up an exit animation in the same way, it doesn't start with a slide ending sequence. Instead, the "Start: On Click" trigger needs to be used and after your exit animation is over you still need one extra click just to advance to the next slide. Workarounds to this are obvious: create a duplicate slide, make your ending animations from the original slide being your starting animations on the duplicate slide and let them be followed with whatever you want or create a transition slide with those ending animations only and set up "Change Advance slide - Automatically after - [the time it takes your animations to finish]". These workarounds will make it work for your audience, visually. However, it has an impact on slide numbers you might need to adjust accordingly and/or duplicate content changes. If you are the only one creating and using your presentation, this might be just fine. But if you are creating a presentation in collaborative mode with three other people and don't even know who will be the presenter at the end, you can mess things up. Let's be specific: most of my slides have 0.2s fly in entrance animation applied to blocks of content coming from right, bottom or left. Advancing to the next slide I want them to fly out in another 0.2s exit animation being followed by new slide 0.2s fly in entrance animation of the new blocks. The swapping of the blocks should be triggered while advancing to the next slide, as usually. As mentioned, I'm not able to achieve this without one extra click between the slides. I wrote a VBA script that should start together with an exit animation and will auto advance a slide after 0.3s when the exit animation is over. That way I should get rid of those extra clicks which are needed right now. Sub nextslide() iTime = 0.3 Start = Timer While Timer < Start + iTime DoEvents Wend With SlideShowWindows(1).View .GotoSlide (ActivePresentation.SlideShowWindow.View.Slide.SlideIndex + 1) End With End Sub It works well when binded on a box, button or another object. But I can't make it run on a single click (anywhere on the slide) so that it could start together with the exit animation onclick trigger. Creating a big transparent rectangular shape over the whole slide and binding the macro on it doesn't help either. By clicking it you only get the macro running, exit animation is not triggered. Anyway, I don't want to bind the macro to any other workaround object but the slide itself. Anyone knows how to trigger a PowerPoint VBA script on slide onclick event? Anyone knows a secret setting that will make the exit animation work as expected i.e. animating right before exiting a slide while transitioning to the next one? Anyone knows how to beat this dragon? Thank you!

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  • IE9 Error: There was a pr?blem sending the command to the program

    - by HK1
    I'm working on a new/fresh Windows 7 32bit machine that now has IE9 installed. The user is using the Dell Stardock application as his primary "desktop" (all his links there). When we place an internet link there and click on it we get the following error message: There was a problem sending the command to the program. To me this indicates that IE9 is having trouble going to the website we want to go to, which should get passed as a parameter to the browser when it opens. I don't think this is a StarDock/ObjectDock problem because we also have some other problems with internet links. For example, we cannot move an internet link from the Desktop to the Quick Launch on the task bar. When we do try, it forces us to put the link with the IE icon as part of the IE menu instead of allowing us to have a shortcut there as it's own entry. I should mention however, that links on the desktop and in the taskbar do work as we expect them too (without showing the above error message). It appears that this problem started after installing Windows Updates. Since we installed a whole bunch of updates at once I have no idea which one caused the problem. I did have Google Chrome installed but I uninstalled it since the user wants to use IE. The problem started before I uninstalled Chrome. I also reset the browser settings on IE9. It didn't help. Next I uninstalled IE9 which took me back to IE8. This actually did resolve the problem but the problem came back as soon as I installed IE9 again. We have Verizon Internet Security installed. It's actually a McAfee product rebranded to look like Verizon. I'm not real crazy over this software but the customer has a subscription so we're not planning to change it. I have no reason to believe that this is causing the problem and yet I know that security software is often to blame for strange issues. I've looked at the registry settings for the following keys and everything appears to be ok for every single one of them: HKEY_CLASSES_ROOT\.htm HKEY_CLASSES_ROOT\.html HKEY_CLASSES_ROOT\http\shell\open\command HKEY_CLASSES_ROOT\http\shell\open\ddeexec\Application HKEY_CLASSES_ROOT\https\shell\open\command HKEY_CLASSES_ROOT\https\shell\open\ddeexec\Application HKEY_CLASSES_ROOT\htmlfile\shell\open\command HKEY_CLASSES_ROOT\Microsoft.Website\Shell\Open\Command Edit1: I've found two potential solutions but I won't be able to try them until tomorrow. One is to disable the "Windows Font Cache" service. Another is to clear IE cache and browsing history. I won't be able to try out either solution until tomorrow since this is a remote client's machine. I see there are lots of other suggestions online but if you take the time to read them through you'll see that the other suggestions didn't fix the problem.

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  • Hardware for multipurpose home server

    - by Michael Dmitry Azarkevich
    Hi guys, I'm looking to set up a multipurpose home server and hoped you could help me with the hardware selection. First of all, the services it will provide: Hosting a MySQL database (for training and testing purposes) FTP server Personal Mail Server Home media server So with this in mind I've done some research, and found some viable solutions: A standard PC with the appropriate software (Either second hand or new) A non-solid state mini-ITX system A solid state, fanless mini-ITX system I've also noted the pros and cons of each system: A standard second hand PC with old hardware would be the cheapest option. It could also have lacking processing power, not enough RAM and generally faulty hardware. Also, huge power consumption heat generation and noise levels. A standard new PC would have top-notch hardware and will stay that way for quite some time, so it's a good investment. But again, the main problem is power consumption, heat generation and noise levels. A non-solid state mini-ITX system would have the advantages of lower power consumption, lower cost (as far as I can see) and long lasting hardware. But it will generate noise and heat which will be even worse because of the size. A solid state, fanless mini-ITX system would have all the advantages of a non-solid state mini-ITX but with minimal noise and heat. The main disadvantage is the read\write problems of flash memory. All in all I'm leaning towards a non-solid state mini-ITX because of the read\write issues of flash memory. So, after this overview of what I do know, my questions are: Are all these services even providable from a single server? To my best understanding they are, but then again, I might be wrong. Is any of these solutions viable? If yes, which one is the best for my purposes? If not, what would you suggest? Also, on a more software oriented note: OS wise, I'm planning to run Linux. I'm currently thinking of four options I've been recommended: CentOS, Gentoo, DSL (Damn Small Linux) and LFS (Linux From Scratch). Any thoughts on this? Any other distro you would recomend? Regarding FTP services, I've herd good things about FileZila. Anyone has any experience with that? Do you recommend it? Do you recommend something else? Regarding the Mail service, I know nothing about this except that it exists. Any software you recommend for this task? Home media, same as mail service. Any recommended software? Thank you very much.

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  • How to find the process(es) which are hogging the machine

    - by Aaron Digulla
    Scenario: All of a sudden, my computer feels sluggish. Mouse moves but windows take ages to open, etc. uptime says the load is 7.69 and raising. What is the fastest way to find out which process(es) are the cause of the load? Now, "top" and similar tools isn't the answer because they either show CPU or memory usage but not both at the same time. What I need is the single command which I might be able to type as it happens - something that will figure out any of System is trying to swap 8GB of RAM to disk because process X ... or process X seeks all over the disk or process X uses 400% CPU" So what I'm looking for is iostat, htop/atop and similar tools run into one with an output like this: 1235 cp - Disk trashing 87 chrome - Uses 2&nbsp;GB of RAM 137 nfs_bench - Uses 95% of the network bandwidth I don't want a tool that gives me some numbers which I can analyze but a tool that tells me exactly which process causes the current load. Assume that the user in front of the keyboard barely knows how to write "process", but the user is quickly overwhelmed when it comes to "resident size", "virtual memory" or "process life cycle". My argument goes like this: A user notices a problem. There can be thousands of reasons ... well, almost :-) The user wants to know the source of the problem. The current solutions give me lots of numbers, and I need to know what these numbers mean. What I'm looking for is a meta tool. 99% of the data is irrelevant to the problem. So what the tool should do is look for processes which hog some resource and list only those along with "this process needs a lot of CPU, this produces many IRQs, this process allocates a lot of RAM (and it's still growing)". This will be a relatively short list. It will be much more simple for someone new to this to locate the culprit from this list than from the output of, say, htop which gives me about 5000 numbers but requires me to fold multi-threaded processes myself (I have 50 lines which say VIRT 2750M but only 16 GB of RAM - the machine ought to swap itself to death but of course, this is a misinterpretation of the data that can happen quickly).

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  • Tips for maximizing Nginx requests/sec?

    - by linkedlinked
    I'm building an analytics package, and project requirements state that I need to support 1 billion hits per day. Yep, "billion". In other words, no less than 12,000 hits per second sustained, and preferably some room to burst. I know I'll need multiple servers for this, but I'm trying to get maximum performance out of each node before "throwing more hardware at it". Right now, I have the hits-tracking portion completed, and well optimized. I pretty much just save the requests straight into Redis (for later processing with Hadoop). The application is Python/Django with a gunicorn for the gateway. My 2GB Ubuntu 10.04 Rackspace server (not a production machine) can serve about 1200 static files per second (benchmarked using Apache AB against a single static asset). To compare, if I swap out the static file link with my tracking link, I still get about 600 requests per second -- I think this means my tracker is well optimized, because it's only a factor of 2 slower than serving static assets. However, when I benchmark with millions of hits, I notice a few things -- No disk usage -- this is expected, because I've turned off all Nginx logs, and my custom code doesn't do anything but save the request details into Redis. Non-constant memory usage -- Presumably due to Redis' memory managing, my memory usage will gradually climb up and then drop back down, but it's never once been my bottleneck. System load hovers around 2-4, the system is still responsive during even my heaviest benchmarks, and I can still manually view http://mysite.com/tracking/pixel with little visible delay while my (other) server performs 600 requests per second. If I run a short test, say 50,000 hits (takes about 2m), I get a steady, reliable 600 requests per second. If I run a longer test (tried up to 3.5m so far), my r/s degrades to about 250. My questions -- a. Does it look like I'm maxing out this server yet? Is 1,200/s static files nginx performance comparable to what others have experienced? b. Are there common nginx tunings for such high-volume applications? I have worker threads set to 64, and gunicorn worker threads set to 8, but tweaking these values doesn't seem to help or harm me much. c. Are there any linux-level settings that could be limiting my incoming connections? d. What could cause my performance to degrade to 250r/s on long-running tests? Again, the memory is not maxing out during these tests, and HDD use is nil. Thanks in advance, all :)

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  • How to prevent dual booted OSes from damaging each other?

    - by user1252434
    For better compatibility and performance in games I'm thinking about installing Windows additionally to Linux. I have security concerns about this, though. Note: "Windows" in the remaining text includes not only the OS but also any software running on it. Regardless of whether it comes included or is additionally installed, whether it is started intentionally or unintentionally (virus, malware). Is there an easy way to achieve the following requirements: Windows MUST NOT be able to kill my linux partition or my data disk neither single files (virus infection) nor overwriting the whole disk Windows MUST NOT be able to read data disk (- extra protection against spyware) Linux may or may not have access to the windows partition both Linux and Windows should have full access to the graphics card this rules out desktop VM solutions for gaming I want the manufacturer's windows graphics card driver Regarding Windows to be unable to destroy my linux install: this is not just the usual paranoia, that has happened to me in the past. So I don't accept "no ext4 driver" as an argument. Once bitten, twice shy. And even if destruction targeted at specific (linux) files is nearly impossible, there should be no way to shred the whole partition. I may accept the risk of malware breaking out of a barrier (e.g. VM) around the whole windows box, though. Currently I have a system disk (SSD) and a data disk (HDD), both SATA. I expect I have to add another disk. If i don't: even better. My CPU is a Intel Core i5, with VT-x and VT-d available, though untested. Ideas I've had so far: deactivate or hide other HDs until reboot at low level possible? can the boot loader (grub) do this for me? tiny VM layer: load windows in a VM that provides access to almost all hardware, except the HDs any ready made software solution for this? Preferably free. as I said: the main problem seems to be to provide full access to the graphics card hardware switch to cut power to disks commercial products expensive and lots of warnings against cheap home built solutions preferably all three hard disks with one switch (one push) mobile racks - won't wear of daily swapping be a problem?

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  • Successfully concatenating multiple videos

    - by wiseguydigital
    My mission is to create videos out of old web slideshows. To start with I have jpegs and audio files that worked as Flash slideshows in an old system, structured such as this: Audio structure my_audio_1.mp3 (this file is a 3 second mp3 of silence) my_audio_2.mp3 my_audio_3.mp3 my_audio_4 etc... roughly 30 mp3s per slideshow Image structure my_image_1.jpg (this acts as the opening slide) my_image_2.jpg my_image_3.jpg my_image_4. etc... roughly 30 images per slideshow. As there are almost 100 slideshows that must be converted to video, I have created a web-based interface using PHP to automate the process, that sits on a local system and attempts to combine the files using shell_exec(). The process uses the following workflow: Loop through each slide and make an avi or mpeg. So for instance my_mini_video_2.avi would be a video that consists of my_image_2.jpg and has a soundtrack of my_audio_2.mp3. This slide would last the length of my_audio_2.mp3. Join / stitch / concat all of the mini videos to create the final video (Using a combination of cat and either mencoder or ffmpeg (I have also tried avimerge but to no avail). Transcode the new 'master' video to various formats such as flv etc. I thought this would be simple and have been close on many occasions but it still won't work. I can't get past stage 2 as I can't get a perfect 'master' video. I have now experimented with Mencoder, FFMpeg and seem to have been through every combination I can think of. The problem is that the audio and visuals never sync, no matter what I try. Also, I have even tried created audio-less mini videos, joining the MP3s into one long MP3 using both cat and mp3wrap and then assigning the new long MP3 as the audio track, but this always produces either a very short file or a badly slowed down file and makes the female voiceover sound like a male boxer!!! There appears to be no problems at all with the original files. Does anybody have any experience in producing a video successfully from the same kind of starting point? Or any ideas on what I may be doing wrong? As an example: If I create silent mini-videos, and stitch them together into 'temp-master.mpg' and then join the MP3s together into single MP3 called 'temp-master-audio.mp3', the audio file's duration is 09:10 and the video file's duration is 08:35. They should be the same and the audio will seem sloooow. I haven't posted code as I have written lots and lots of combinations.

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