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  • Linux Kernel Packet Forwarding Performance

    - by Bob Somers
    I've been using a Linux box as a router for some time now. Nothing too fancy, just enabling forwarding in the kernel, turning on masquerading, and setting up iptables to poke a few holes in the firewall. Recently a friend of mine pointed out a performance problem. Single TCP connections seem to experience very poor performance. You have to open multiple parallel TCP connections to get decent speed. For example, I have a 10 Mbit internet connection. When I download a file from a known-fast source using something like the DownThemAll! extension for Firefox (which opens multiple parallel TCP connections) I can get it to max out my downstream bandwidth at around 1 MB/s. However, when I download the same file using the built-in download manager in Firefox (uses only a single TCP connection) it starts fast and the speed tanks until it tops out around 100 KB/s to 350 KB/s. I've checked the internal network and it doesn't seem to have any problems. Everything goes through a 100 Mbit switch. I've also run iperf both internally (from the router to my desktop) and externally (from my desktop to a Linux box I own out on the net) and haven't seen any problems. It tops out around 1 MB/s like it should. Speedtest.net also reports 10 Mbits speeds. The load on the Linux machine is around 0.00, 0.00, 0.00 all the time, and it's got plenty of free RAM. It's an older laptop with a Pentium M 1.6 GHz processor and 1 GB of RAM. The internal network is connected to the built in Intel NIC and the cable modem is connected to a Netgear FA511 32-bit PCMCIA network card. I think the problem is with the packet forwarding in the router, but I honestly am not sure where the problem could be. Is there anything that would substantially slow down a single TCP stream?

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  • PHP/MySQL Performance Testing with Just PHP

    - by Mike Gifford
    I'm trying to diagnose a server where the website is loading very slowly, but unfortunately my client has only provided me with FTP access. I've got FTP access so I can upload PHP scripts, but can't set up any other server side tools. I have access to phpMyAdmin, but not direct access to the MySQL server. It is also unfortunately a Windows server (and we've been a Linux shop for over a decade now). So, if I wan to evaluate MySQL & disk speed performance through PHP on a generic server, what is the best way to do this? There are already tools like: https://github.com/raphaelm/php-benchmark or https://github.com/InfinitySoft/php-benchmark But I'm surprised there isn't something that someone has already set up & configured to just run through and do some basic testing of a server's responsiveness. Every time we evaluate a new server environment it's handy to be able to compare it to an existing one quickly to see if there are any anomalies. I guess I'd just hoped that someone else had written up a script to do this already. I know I have, but that was before Github when there was a handy place to post scraps of code like this. Originally posted in http://stackoverflow.com/questions/12321498/php-mysql-performance-testing-with-just-php but it was recommended that I re-post it here.

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  • IIS High use & Server Performance issues

    - by HaydnWVN
    Have an SBS2011 running Exchange, a database app and a few other things serving 5 users (3 low use, 1 high). The server was never specced for the database app so it isn't as powerful as I'd like... Only 12GB RAM. We have increasingly found performance problems with this server, last week it was so bad I couldn't even connect remotely. To free up some available RAM I have (over the past month or so): Restricted the Exchange Message Store to 1GB with (so far) no ill effects. Restricted SQL Databases (including SBSMonitoring and Sharepoint/##SSEE (Which isn't used)). Now I am finding that IIS Worker threads are using up the available memory and I have (so far) been unable to track down much useful information about restricting them. This server is not 'serving' anything web-based apart from OWA that I am finding people using because Outlook is so slow (again related to the Servers performance). I am aware that Exchange on SBS2011 is designed to use up available resources (and concede when other applications request). But it is not doing so (or anywhere near fast enough) for our needs. Opening the database application (using Postgres) takes 5+ minutes from client machines and regularly times out or crashes due to this. After a reboot (before SQL/Exchange/IIS databases are very large/totally cached) we get the performace we need and expect. Previously a reboot once a month was enough... Then once a week... Now they have taken to rebooting it almost daily!

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  • Very slow write performance on Debian 6.0 (AMD64) with DMCRYPT/LVM/RAID1

    - by jdelic
    I'm seeing very strange performance characteristics on one of my servers. This server is running a simple two-disk software-RAID1 setup with LVM spanning /dev/md0. One of the logical volumes /dev/vg0/secure is encrypted using dmcrypt with LUKS and mounted with the sync and noatimes flag. Writing to that volume is incredibly slow at 1.8 MB/s and the CPU usage stays near 0%. There are 8 crpyto/1-8 processes running (it's a Intel Quadcore CPU). I hope that someone on serverfault has seen this before :-(. uname -a 2.6.32-5-xen-amd64 #1 SMP Tue Mar 8 00:01:30 UTC 2011 x86_64 GNU/Linux Interestingly, when I read from the device I get good performance numbers: reading without encryption: $ dd if=/dev/vg0/secure of=/dev/null bs=64k count=100000 100000+0 records in 100000+0 records out 6553600000 bytes (6.6 GB) copied, 68.8951 s, 95.1 MB/s reading with encryption: $ dd if=/dev/mapper/secure of=/dev/null bs=64k count=100000 100000+0 records in 100000+0 records out 6553600000 bytes (6.6 GB) copied, 69.7116 s, 94.0 MB/s However, when I try to write to the device: $ dd if=/dev/zero of=./test bs=64k 8809+0 records in 8809+0 records out 577306624 bytes (577 MB) copied, 321.861 s, 1.8 MB/s Also, when I read I see CPU usage, when I write, the CPU stays at almost 0% usage. Here is output of cryptsetup luksDump: LUKS header information for /dev/vg0/secure Version: 1 Cipher name: aes Cipher mode: cbc-essiv:sha256 Hash spec: sha1 Payload offset: 2056 MK bits: 256 MK digest: dd 62 b9 a5 bf 6c ec 23 36 22 92 4c 39 f8 d6 5d c1 3a b7 37 MK salt: cc 2e b3 d9 fb e3 86 a1 bb ab eb 9d 65 df b3 dd d9 6b f4 49 de 8f 85 7d 3b 1c 90 83 5d b2 87 e2 MK iterations: 44500 UUID: a7c9af61-d9f0-4d3f-b422-dddf16250c33 Key Slot 0: ENABLED Iterations: 178282 Salt: 60 24 cb be 5c 51 9f b4 85 64 3d f8 07 22 54 d4 1a 5f 4c bc 4b 82 76 48 d8 a2 d2 6a ee 13 d7 5d Key material offset: 8 AF stripes: 4000 Key Slot 1: DISABLED Key Slot 2: DISABLED Key Slot 3: DISABLED Key Slot 4: DISABLED Key Slot 5: DISABLED Key Slot 6: DISABLED Key Slot 7: DISABLED

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  • How to configure VirtualBox server for performance at home

    - by BluJai
    I currently have two physical Ubuntu Server 10.10 servers at home: one serves as our firewall/router/DHCP/VPN server and the other performs double-duty as a file server and a VirtualBox host for an Ubuntu Desktop 10.10 machine which I use from remote connections (via NoMachine) for many thin-client purposes which are irrelevant to my question. What I'd like to accomplish is to consolidate the two physical machines into one which is a dedicated VirtualBox host (most likely running Ubuntu Server 10.10). Note that I'd like to stick with VirtualBox (if possible) because I'm most comfortable with it and use it on a daily basis at both home and work. Specifically, I plan to have one VM set up as file server, another as the firewall/router/DHCP/VPN (or possibly split those a bit) and a third, which is the only current VM (already VirtualBox), which is the thin-client host. My question comes down to performance and/or recommendations about the file server VM. The file server hosts about 6 terabytes of data across 4 drives. What I'd like to do is use raw disk access from the VM directly to the existing disks. However, I'm curious what performance advantage/disadvantage that would have as compared to using shared folders from the VM host and basically just have the whole drive served as a shared folder to the VM which would then serve it to the other machines on the network. I don't know if virtual disks would even work in this scenario and I certainly wouldn't want a drive to be filled with just a single file which is 1.5 TB (disk image). To add understanding of context, but not to get additional advice, I want to virtualize these machines because I intend to regularly use the snapshot capabilities of VirtualBox for the system disks (which will be virtual drives) of the VMs and I have some physical space/power needs to address (as I mentioned, this is at home).

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  • Slow performance on VMWare Linux server after Tomcat install

    - by Loftx
    We have a VMWare ESXi 4.1 server hosting a number of Linux and Windows guests. Recently a new Linux guest was added to this server and seemed to be performing well. Tomcat and some other applications on this server were then installed which seem to have caused the server to run really slowly without any obvious resource issues. Slow performance include: The time taken to bring up the password prompt over ssh takes a few seconds when it was previously instantaneous. The time taken to unzip a zip file which was previously a few seconds now takes around 30 seconds The time taken to compile vmware tools has increased by similar factors Both the VMWare console and monitoring commands don't report any issues with high CPU or memory usage but something is obviously slowing the server down somehow. Does anyone have any ideas what may be causing this issue and how it can be resolved? Thanks, Tom Edit As per your questions I’ve looked at some of the performance indicators on both the VM host and VM guest indicated. Firstly I tried reserving the full amount of memory (3gb) for this VM – no other machines on this server have any memory reservation. The swap in rate and swap out rate for the VM host and guest are now both zero. Balloon memory on the guest is zero and on the host is 3.5gb (total memory on the host is 12gb) The swap rate for the guest is also zero. Swap used by the host is 200mb on average. Compression and decompression rates for the host and guest are zero. Command aborts for the host are zero. Read latency is very low – maximum 10ms average 0.8ms. Write latency is higher – a few spikes to 170ms but mostly around 25ms – is this bad? Queue command latency is zero . Physical disk read latency averages 5ms but often 10ms Physical disk write latency averages 15ms but is often 20ms I hope this helps - let me know if you need any more information.

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  • Windows 7 network performance tuning for LAN

    - by Hubert Kario
    I want to tune Windows 7 TCP stack for speed in a LAN environment. Bit of background info: I've got a Citrix XenServer set up with Windows 2008R2, Windows 7 and Debian Lenny with Citrix kernel, Windows machines have Tools installed the iperf server process is running on different host, also Debian Lenny. The servers are otherwise idle, tests were repeated few times to confirm results. While testing with iperf 2008R2 can achieve around 600-700Mbps with no tuning what so ever but I can't find any guide or set of parameters that will make Windows 7 achieve anything over 150Mbps with no change in TCP window size using -w parameter to iperf. I tried using netsh autotuining to disabled, experimental, normal and highlyrestricted - no change. Changing congestionprovider doesn't do anything, just as rss and chimney. Setting all the available settings to same values as on Windows 2008R2 host doesn't help. To summarize: Windows 2008R2 default settings: 600-700Mbps Debian, default settings: 600Mbps Windows 7 default settings: 120Mbps Windows 7 default, iperf -w 65536: 400-500Mbps While the missing 400Mbps in performance I blame on crappy Realtek NIC in the XenServer host (I can do ~980Mbps from my laptop to the iperf server) it doesn't explain why Windows 7 can't achieve good performance without manually tuning window size at the application level. So, how to tune Windows 7?

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  • How to configure VirtualBox server for performance at home

    - by BluJai
    I currently have two physical Ubuntu Server 10.10 servers at home: one serves as our firewall/router/DHCP/VPN server and the other performs double-duty as a file server and a VirtualBox host for an Ubuntu Desktop 10.10 machine which I use from remote connections (via NoMachine) for many thin-client purposes which are irrelevant to my question. What I'd like to accomplish is to consolidate the two physical machines into one which is a dedicated VirtualBox host (most likely running Ubuntu Server 10.10). Note that I'd like to stick with VirtualBox (if possible) because I'm most comfortable with it and use it on a daily basis at both home and work. Specifically, I plan to have one VM set up as file server, another as the firewall/router/DHCP/VPN (or possibly split those a bit) and a third, which is the only current VM (already VirtualBox), which is the thin-client host. My question comes down to performance and/or recommendations about the file server VM. The file server hosts about 6 terabytes of data across 4 drives. What I'd like to do is use raw disk access from the VM directly to the existing disks. However, I'm curious what performance advantage/disadvantage that would have as compared to using shared folders from the VM host and basically just have the whole drive served as a shared folder to the VM which would then serve it to the other machines on the network. I don't know if virtual disks would even work in this scenario and I certainly wouldn't want a drive to be filled with just a single file which is 1.5 TB (disk image). To add understanding of context, but not to get additional advice, I want to virtualize these machines because I intend to regularly use the snapshot capabilities of VirtualBox for the system disks (which will be virtual drives) of the VMs and I have some physical space/power needs to address (as I mentioned, this is at home).

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  • graphics performance better on battery?

    - by Scott Beeson
    Anyone have any idea why my laptop would perform (considerably) better while on battery than while plugged in? It's a Dell Latitude E6420 with Windows 8 Pro. I tried mirroring all the settings in the selected power plan from "On battery" to "Plugged In" and that didn't help. I then just restored the defaults for all power plans (balanced and high performance). I'm still seeing the same results. The best example where it is most noticeable (don't laugh) is Sim City Social in Chrome. I'm probably seeing a performance increase of 5x on battery versus plugged in. This is easily reproducible too. I'm very confused. Could it be caused by dust? The laptop isn't that old and there is no visible dust. I'm not going to take it apart to check the insides as it's a corporate laptop. Could it be overheating? Battery Sim City Social: 68 degrees max Civ V: 77 degrees max Charger Sim City Social: 68 Civ V: did not test See answer below... I'm retarded

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  • Difference in performance: local machine VS amazon medium instance

    - by user644745
    I see a drastic difference in performance matrix when i run it with apache benchmark (ab) in my local machine VS production hosted in amazon medium instance. Same concurrent requests (5) and same total number of requests (111) has been run against both. Amazon has better memory than my local machine. But there are 2 CPUs in my local machine vs 1 CPU in m1.medium. My internet speed is very low at the moment, I am getting Transfer rate as 25.29KBps. How can I improve the performance ? Do not know how to interpret Connect, Processing, Waiting and total in ab output. Here is Localhost: Server Hostname: localhost Server Port: 9999 Document Path: / Document Length: 7631 bytes Concurrency Level: 5 Time taken for tests: 1.424 seconds Complete requests: 111 Failed requests: 102 (Connect: 0, Receive: 0, Length: 102, Exceptions: 0) Write errors: 0 Total transferred: 860808 bytes HTML transferred: 847155 bytes Requests per second: 77.95 [#/sec] (mean) Time per request: 64.148 [ms] (mean) Time per request: 12.830 [ms] (mean, across all concurrent requests) Transfer rate: 590.30 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.5 0 1 Processing: 14 63 99.9 43 562 Waiting: 14 60 96.7 39 560 Total: 14 63 99.9 43 563 And this is production: Document Path: / Document Length: 7783 bytes Concurrency Level: 5 Time taken for tests: 33.883 seconds Complete requests: 111 Failed requests: 0 Write errors: 0 Total transferred: 877566 bytes HTML transferred: 863913 bytes Requests per second: 3.28 [#/sec] (mean) Time per request: 1526.258 [ms] (mean) Time per request: 305.252 [ms] (mean, across all concurrent requests) Transfer rate: 25.29 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 290 297 14.0 293 413 Processing: 897 1178 63.4 1176 1391 Waiting: 296 606 135.6 588 1171 Total: 1191 1475 66.0 1471 1684

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  • Performance associated with storing millions of files on NTFS

    - by Tim Brigham
    Does anyone have a method / formula, etc that I could use - hopefully based on both current and projected numbers of files - to project the 'right' length of the split and the number of nested folders? Please note that although similar it isn't quite the same as Storing a million images in the filesystem. I'm looking for a way to help make the theories outlined more generic. Assumptions I have 'some' initial number of files. This number would be arbitrary but large. Say 500k to 10m+. I have considered the underlying physical hardware disk IO requirements that would be necessary to support such an endeavor. Put another way As time progresses this store will grow. I want to have the best balance of current performance and as my needs increase. Say I double or triple my storage. I need to be able to address both current needs and projected future growth. I need to both plan ahead and not sacrifice too much of current performance. What I've come up with I'm already thinking about using a hash split every so many characters to split things out across multiple directories and keeping the trees even, very similar as outlined in the comments in the question above. It also avoids duplicate files, which would be critical over time. I'm sure that the initial folder structure would be different based on what I've outlined, and depending on the initial scale. As far as I can figure there isn't a one size fits all solution here. It would be horrendously time intensive to work something out experimentally.

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  • VMWare Workstation Linux Host performance tuning

    - by Hoghweed
    I need to improve my linux hosted vmware workstation for using multiple virtual machines at the same time. I feel very stupid I lost a great blog post link which I found last month (and I'm not able to find it again..) so I try to ask here if anyone can help me: This is my host (laptop): 16GB DDR3 Ram HDD Hybrid 750GB 7200 (8GB SSD Cache) Mint 15 x64 Kernel 3.9.7 swappiness set to 10 The above are the important things about the host. So, My need is the ability to run 2 or 3 VMs at the same time. The lack of performance is about the disk, The last time from that blog post I lost, I setup /tmp to be mounted ad a memory partition and in my previous installation that was good, now I'm not able to find a good solution to tweak the things. I think with 16GB o RAM there will be no problems to run multiple VMs, but whe they start to swap or use the /tmp things going bad (guest cursor going too fast after a freeze, guest freeze and so on) Anyone can help me to fit a good host tweak and configuration to get better performance? Thanks in advance

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  • CloudFlare dashboards empty, or performance issues

    - by Katafalkas
    I wanted to test CloudFlare performance so I set my image gallery domain on it and started testing. I have added PageRules for caching. And chose the Security: Essentially Off. I checked NS check tools and they say that my domain name is propagated with CloudFlare. For testing purpose I created a link that loads 200 images from that server, and was using loads.in website to determine how much it is faster. After trying few regions, I noticed that there were no improvement in loading speed. So I looked up the dashboards, and it was empty. I am not sure if I am doing something wrong, or made some error in my setup, or it takes few days to start caching or working properly, but at the moment - after a day of testing - dashboards are empty. Also the NS check tools sais that all name servers are propagated to CloudFlare and working fine. So I assume I got a bad performance because it is simply not working. I sent a letter to CloudFlare support team, but did not get any straight answer. So essentially my question is: Anyone has any experience with CloudFlare ? How long does it take for it to start caching static content to CDN ? Or there is simply something I am doing wrong ?

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  • Xubuntu vs Ubuntu 10.04 Performance

    - by wag2639
    I know it just came out today, but are there any statistics with memory requirements, system resources, power usage, and performance to decide which is better Xubuntu or Ubuntu (XFCE vs Gnome)? My main concern is running it as secondary OS on my Lenovo T400 laptop to just get online quickly and using SSH from a terminal to connect to remote web servers.

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  • How do you fix the Performance Dashboard datetime overfow error

    - by Mike L
    I'm a programmer/DBA by accident and we're running SQL Server 2005 with Performance Dashboard for basic monitoring. The server has been up for a few weeks and now we can't drill into certain reports. Is there any way to reset these reports without a complete reboot? edit: I bet the error message would help. I get this when I drill into the CPU graph: Error: Difference of two datetime columns caused overflow at runtime.

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  • Disk performance below expectations

    - by paulH
    this is a follow-up to a previous question that I asked (Two servers with inconsistent disk speed). I have a PowerEdge R510 server with a PERC H700 integrated RAID controller (call this Server B) that was built using eight disks with 3Gb/s bandwidth that I was comparing with an almost identical server (call this Server A) that was built using four disks with 6Gb/s bandwidth. Server A had much better I/O rates than Server B. Once I discovered the difference with the disks, I had Server A rebuilt with faster 6Gbps disks. Unfortunately this resulted in no increase in the performance of the disks. Expecting that there must be some other configuration difference between the servers, we took the 6Gbps disks out of Server A and put them in Server B. This also resulted in no increase in the performance of the disks. We now have two identical servers built, with the exception that one is built with six 6Gbps disks and the other with eight 3Gbps disks, and the I/O rates of the disks is pretty much identical. This suggests that there is some bottleneck other than the disks, but I cannot understand how Server B originally had better I/O that has subsequently been 'lost'. Comparative I/O information below, as measured by SQLIO. The same parameters were used for each test. It's not the actual numbers that are significant but rather the variations between systems. In each case D: is a 2 disk RAID 1 volume, and E: is a 4 disk RAID 10 volume (apart from the original Server A, where E: was a 2 disk RAID 0 volume). Server A (original setup with 6Gpbs disks) D: Read (MB/s) 63 MB/s D: Write (MB/s) 170 MB/s E: Read (MB/s) 68 MB/s E: Write (MB/s) 320 MB/s Server B (original setup with 3Gpbs disks) D: Read (MB/s) 52 MB/s D: Write (MB/s) 88 MB/s E: Read (MB/s) 112 MB/s E: Write (MB/s) 130 MB/s Server A (new setup with 3Gpbs disks) D: Read (MB/s) 55 MB/s D: Write (MB/s) 85 MB/s E: Read (MB/s) 67 MB/s E: Write (MB/s) 180 MB/s Server B (new setup with 6Gpbs disks) D: Read (MB/s) 61 MB/s D: Write (MB/s) 95 MB/s E: Read (MB/s) 69 MB/s E: Write (MB/s) 180 MB/s Can anybody suggest any ideas what is going on here? The drives in use are as follows: Dell Seagate F617N ST3300657SS 300GB 15K RPM SAS Dell Hitachi HUS156030VLS600 300GB 3.5 inch 15000rpm 6GB SAS Hitachi Hus153030vls300 300GB Server SAS Dell ST3146855SS Seagate 3.5 inch 146GB 15K SAS

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  • Performance issues concurrently running MySQL and MS SQL Sever

    - by pacifika
    We're considering installing MySQL on the same database server that has been running MS SQL Server. From my research there are no technical issues running both concurrently, but I am worried that the performance will be affected. Is by default SQL Server set up to use all available memory for example? What should I look out for? Thanks

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