Questions about server hardware and software performance, or network performance.

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Understanding RedHat's recommended tuned profiles

We are going to roll out tuned (and numad) on ~1000 servers, the majority of them being VMware servers either on NetApp or 3Par storage. According to RedHats documentation we should choose the ...
6
votes
9answers
4k views

Linux Server Performance Monitoring

I'm looking to monitor performance on my Linux servers (which happen to be Centos). What are the best tools for monitoring things in realtime such as: Disk Performance I/O, swapping etc.. CPU ...
6
votes
2answers
5k views

In absense of iotop which command is most appropriate for get i/o bounded process

Suggest me best way to list io bounded process. I know iotop is best way to get list but want any alternate option since my system showing a large number of D state process.
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6answers
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Find the bottleneck: disk I/O on Windows XP

One of our development boxes has developed a problem wherein performance will occasionally drop through the floor. When this happens, you can hear the hard drive thrashing, but I don't know what's ...
6
votes
4answers
5k views

Performance difference between compiled and binary linux distributions/packages

I was searching a lot on the internet and couldn't find an exact answer. There are distros like Gentoo (or FreeBSD) which does not come with binaries but only with source code for packages (ports). ...
6
votes
4answers
2k views

Will a database server perform better running on 2 CPUs with 16 cores or 4 CPUs with 8 cores?

What I have: an online financial application (ASP.NET, C#) at peak we have 5K+ simultaneous users backend is running on Oracle 11g (active server + stand-by using Active Data Guard). At peak - 4K-5K ...
6
votes
4answers
6k views

Nagios remote monitoring: NRPE Vs. SSH

We use Nagios to monitor quite a few (~130) servers. We monitor CPU, Disk, RAM and a few other things on each server. I've always used SSH to run the remote commands, purely because it requires little ...
6
votes
2answers
3k views

ZFS with L2ARC (SSD) slower for random seeks than without L2ARC

I am currently testing ZFS (Opensolaris 2009.06) in an older fileserver to evaluate its use for our needs. Our current setup is as follows: Dual core (2,4 GHz) with 4 GB RAM 3x SATA controller with ...
6
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1answer
1k views

Is it bad practice to run a web application server directly on port 80/443

I am hosting a web app on amazon aws, using an ec2 instance. On that instance i will be running only one application. using glassfish v3.0.1 I do not want to run the app using : ...
6
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5answers
4k views

How to measure disk throughput?

I want to know how many bytes per second can I write to the disk and read from it. How can I do that on linux machine?
6
votes
1answer
5k views

HP DL380 G7 + Smart Array P410i + sysbench -> poor raid 10 performance

I have running system with low IO utilization: HP DL380G7 ( 24gb RAM ) Smart Array p410i with 512mb battary backed write cache 6x SAS 10k rpm 146gb drives in RAID10 Debian Squeze linux, ext4 + LVM, ...
6
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3answers
35k views

How to set shmall, shmmax, shmni, etc … in general and for postgresql

I've used the documentation from PostgreSQL to set it for example this config: >>> cat /proc/meminfo MemTotal: 16345480 kB MemFree: 1770128 kB Buffers: 382184 kB ...
6
votes
4answers
597 views

Suggestions for recommended file system for Linux server

There are many file systems for a Linux server administrator to choose from. Also, it is not always an easy task to figure out the appropriate layout and optimal file system for your needs. Can you ...
6
votes
2answers
3k views

Why does apache slow down overnight?

Greetings experts, On my dedicated CentOS 5.4 server, I configure apache with about a dozen virtual hosts. I test a few of 'em, each loads within about a second; fairly quick. Load average is less ...
6
votes
6answers
13k views

How to troubleshoot slow Windows XP boot?

I have a Windows XP x64 SP2 machine that used to boot up really quickly, but now takes a very long time. If I enable the /sos boot switch it gets to the bit where it says: 2 system processors [8191MB ...
6
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2answers
2k views

does adding heaps of drives to a raid 0 increase performance?

does adding heaps of drives to a raid 0 increase performance? i know that two drives in a striped raid will usually be faster than a single drive but will i notice a difference in performance between ...
6
votes
1answer
146 views

How to prevent IO Load under Linux for Video serving?

I'm currently serving videos of conferences via Nginx on 3 servers; 4 cores, enough memory (no swap used) and RAID-10 with 8 drives per server. Unfortunately iostat -xd 1 gives me 100% on all 3 ...
6
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6answers
18k views

IO Wait causing so much slowdown (EXT4 JDB2 at 99% IO ) During Mysql Commit

I am writing an indexer, using python, which indexes documents and insert them into Database, Before it was single process but now i made it to multiprocessing with 4 parallel processes running.After ...
6
votes
3answers
9k views

Configuring Varnish to rewrite Expires/Cache-Control headers for client-side caching

How do I configure Varnish so that all responses to requests matching say "*.css" gets cached in the client's browser for 30 days? What I'm trying to achieve is making Varnish set the correct ...
6
votes
3answers
3k views

Best Linux network tuning tips? [closed]

I figure it's a good idea to have a central question for linux network tuning. I'm particularly interested in tuning options for the following. Web server Varnish / Squid server DB server File ...
6
votes
2answers
174 views

What Linux command do I type to see my MySQL server load in real time?

What Linux command can I type where I can watch MySQL server load in real time? BACKGROUND: I can type 'top' and watch overall server load (just look at inverse of Idle % and consider it over a ...
6
votes
2answers
3k views

pg_restore taking much longer than pg_dump

I am regularly saving and later restoring a smallish PostgreSQL database, which is used for testing. Its data is updated regularly as a result of tests, then a new dump must be made, and the dumps are ...
6
votes
6answers
3k views

Windows 2008 Server on mixed ethernet speeds — download from share slow, but fast plain TCP

I have a Windows Server 2008 R2 x64 server that is AD controller and file server. I have a problem that Windows XP clients experience terribly slow (less than 10Mbps, really less than ...
6
votes
2answers
12k views

Why do MySQL queries pile up in “Sending data” state?

We're using InnoDB tables as the back end of a web application, and everything was fine for about two years until we had to restart MySQL a few weeks ago. (We hadn't disabled reverse DNS lookups, ...
6
votes
7answers
12k views

How many files in a directory is too many? (Downloading data from net)

Greetings, I'm writing some scripts to process images from various photo websites. Right now I'm storing all this data in individual text files in the same directory. The directory is web ...
6
votes
1answer
10k views

How is memcache distributed?

I've got memcache running on 5 web servers all of which are on the host list in php and which are load balanced on the front end. So since memcached is supposed to be distributed the php client will ...
6
votes
1answer
294 views

4X10GB Bonded NIC - only producing 4-5GB throughput

I have Two HPBL685c G6 blade servers running Ubuntu 15.04 Each server has 4X10GB NIC 2x10GB NIC are connected to a single VirtualConnect 10/10G Ethernet module The other 2x10GB NIC are connected to ...
6
votes
3answers
236 views

PHP + MYSQL site perfomance

I have to manage a site which wasn't developed by me. It is in PHP using a mysql database, which is located in the web server. The site, sometimes (when the visitors increase too much) stops ...
6
votes
3answers
4k views

Apache + Tomcat VS Stand Alone Tomcat or GlassFish

I am setting up a Debian server to serve Java web applications. I have done quite a bit of research for several weeks now. Tomcat's web site says it is better to use stand alone Tomcat for speed if ...
6
votes
1answer
100 views

postfix performance with lists in main.cf

For defining a list of items to assign to many different options in postfix, you can either use a comma separated list like this: relay_domains = example.com,example.net,example.org or a hash map ...
6
votes
2answers
270 views

Calling sync/fsync slows IO after 30 minutes uptime

After 30 minutes of uptime using Ubuntu 14.04 with an ext4 hybrid SSD I see many processes blocking IO using iotop. The root cause of this slowdown has been traced back to the Unix system call sync. ...
6
votes
2answers
1k views

Why is Postgres sitting 95% idle, with no file I/O?

I have a TileMill/PostGIS stack running on an 8 core Ubuntu 12.04 VM on an OpenStack cloud. It's a rebuild of a very similar system which was running nicely on very similar hardware (same cloud, but ...
6
votes
1answer
2k views

Does APC really improve performance with PHP 5.3+

According to a Linux Adminstrator over at Hostgator: With PHP 5.3 having APC installed is not needed as PHP 5.3 already has improvements that APC does resolve in it. Is that statement actually ...
6
votes
2answers
2k views

Too much I/O generated by postgres stats collector process

I am using XenServer with several virtual machines having local postgres databases. Even when all applications are unused and the databases are idle, each vm causes constant storage network traffic ...
6
votes
3answers
682 views

A strategy for network monitoring to improve network health?

The goal is to find out which parts of network should be upgraded / reorganized to improve network health (reliability and performance). What are the methods to monitor network traffic, detect ...
6
votes
4answers
561 views

Best performance: 1tb vs larger drives in app using only sequential read/writes

I have a custom app that is multi-threaded; each thread runs on its own logical core (the workstation is a dual xeon, with 12 physical and 24 logical cores). So there are 24 threads running ...
6
votes
2answers
1k views

Apache's htcacheclean doesn't scale: How to tame a huge Apache disk_cache?

We have an Apache setup with a huge disk_cache (>500.000 entries, >50 GB disk space used). The cache grows by 16 GB every day. My problem is that the cache seems to be growing nearly as fast as it's ...
6
votes
4answers
2k views

better TCP performance over a “high delay network”

I’m trying to improve my TCP throughput over a “high delay network” between Linux machines. I set tcp_mem, tcp_wmem and tcp_rmem to “8192 7061504 7061504”. I set rmem_max, wmem_max, rmem_default and ...
6
votes
4answers
2k views

My linux server takes more than an hour to boot. Suggestions?

I am building a CentOS 5.4 system that boots off a compact flash card using a card reader that emulates an IDE drive. It literally takes about an hour to boot. The ultra-slow part occurs when Grub ...
6
votes
5answers
7k views

How can I replay Apache access logs back at my servers to do real world load testing?

I looked at http://serverfault.com/questions/2107/tools-for-load-testing-http-servers but I couldn't see how to replay my own existing logs in any of those tools. I have a bug that only occurs under ...
6
votes
2answers
7k views

Relation between disk IOPS and sar tps

I'm trying to estimate IOPS requirements of my application running on 32-bit CentOS 6.2. I started to take some measurement on a machine with SATA disks and I'm quite confused of difference between ...
6
votes
1answer
1k views

Very uneven CPU utilization with SQL Server 2012 on 2 processor computer with 16 cores / processor

After installing SQL Server Enterprise 2012 with the Server + Cal license model, on a computer with 2 processors each with 16 cores (and no hyperthreading involved) and putting the server under ...
6
votes
2answers
5k views

Why would Linux VM in vSphere ESXi 5.5 show dramatically increased disk i/o latency?

I'm stumped and I hope someone else will recognize the symptoms of this problem. Hardware: new Dell T110 II, dual-core Pentium G850 2.9 GHz, onboard SATA controller, one new 500 GB 7200 RPM cabled ...
6
votes
3answers
10k views

IIS: How to tell if a slow time-taken is due to a slow network connection

According to http://support.microsoft.com/kb/944884, "when a large response or large responses are sent to a client over a slow network connection, the value of the time-taken field may be more than ...
6
votes
4answers
5k views

iotop shows kswapd0 at 99.99% with 0% DISK READ and DISK WRITE

I have a heavy postgres query. It takes over ten minutes to run. I'd like to upgrade my hardware to get it run faster. I think more RAM will help, but my motherboard is full so I'll need a whole ...
6
votes
1answer
3k views

Why do I see a large performance hit with DRBD?

I see a much larger performance hit with DRBD than their user manual says I should get. I'm using DRBD 8.3.7 (Fedora 13 RPMs). I've setup a DRBD test and measured throughput of disk and network ...
6
votes
1answer
229 views

Is it possible to process millions of datagrams per second with Windows, using a vendor agnostic API? [closed]

I am investigating if I can implement an HPC app in Windows that receives small UDP multicast datagrams (mostly 100-400 Bytes) at a high rate, using a dozen or up to maybe 200 multicast groups (i.e. ...
6
votes
1answer
1k views

IPSec software that can use multiple CPU cores

Can anyone recommend a good IPSec software that can use multiple CPU cores to achieve performance ~2Gbps on Linux dual-CPU quad-core E5620 Xeon setup (total 16HT cores)? I have tried OpenSwan and ...
6
votes
1answer
195 views

Odd performance fluctation with php-fpm and nginx

I'm running a load test against a web service. It's a php application running on php-fpm and nginx, with fastcgi. There is a MySQL backend being used for small reads only. Invariably, I'm seeing a ...
6
votes
0answers
122 views

Fast distributed filesystem for a large amounts of data with metadata in database [closed]

My project uses several processing machines and one storage machine. Currently storage organized with a MSSQL filetable shared folder. Every file in storage have some metadata in database. Processing ...