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

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6
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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
votes
2answers
503 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
141 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
votes
6answers
14k 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
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
170 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
3answers
30k 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
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
10k 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
6answers
10k 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
2answers
2k views

Importance of disk alignment for Windows Server 2012

I saw article about Disk alignment here and also here.Also there where some references that windows server 2003 has some problem with disk alignment. After reading article I am confused whether we ...
6
votes
3answers
3k views

PostgreSQL slow commit performance

We are having some problems with a PostgreSQL configuration. After some benchmarks I found out that very simple queries are taking a relatively long time, upon furter inspection it appears that the ...
6
votes
3answers
235 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
1answer
8k 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
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
211 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
1answer
86 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
218 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
1answer
5k views

Nginx auto minify html output

does anyone know of a way to get nginx (or any other method) to minify html output on the fly? It seems straightforward to me and can shave a few kb off and help speed up the site.
6
votes
3answers
669 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
548 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
4answers
1k 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
6k 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
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
167 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
0answers
107 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 ...
6
votes
4answers
7k views

3.5“ 15k RPM drives vs 2.5” 10k RPM drives

How do 2.5" 10k RPM SAS drives perform compared to 3.5" 15k RPM SAS drives? Specific areas of comparison: Random write Random read Sequential write Sequential read
5
votes
3answers
18k views

Measure Linux IOPS for a running system

How do I measure IOPS of a running Linux server? I know that the theoretical IOPS of a SATA drive is around 90 and enterprise 10k SAS/FC disk is 180. I want to know how much my running system is using ...
5
votes
7answers
9k views

How to optimize performance for MSSQL databases?

I'm a dba with a database with ~280 tables, and total datasize of ~1,5GB. I'd like to tune the database to make it perform better. What do you do to keep your SQL databases performant? How much ...
5
votes
7answers
2k views

setup lowcost image storage server with 24x SSD array to get high IOPS?

I want to build let's name it a lowcost Ra*san which would host for our social site the images (many millions) we have 5 sizes of every photo with 3 KB, 7 KB, 15 KB, 25 KB and 80 KB per Image. My ...
5
votes
7answers
12k views

Speeding up rsync over smb

I'm backing up a Linux box over SMB to a NAS. I mount the NAS locally and then I rsync a lot of data (100GB or so). I believe it's taking an awfully long time to do it: more than 12 hours. I would ...
5
votes
12answers
1k views

Optimum way to serve 70,000 static files (jpg)?

I need to serve around 70,000 static files (jpg) using nginx. Should I dump them all in a single directory, or is there a better (efficient) way ? Since the filenames are numeric, I considered having ...
5
votes
5answers
872 views

Linux: how many disk I/O does it take to read a file? How to minimize it?

According to this paper on Facebook's Haystack: "Because of how the NAS appliances manage directory metadata, placing thousands of files in a directory was extremely inefficient as the ...
5
votes
4answers
8k views

How do I configure RAID 5, especially stripe size, with 24 x 1.2 TB drives for CentOS 6?

For a Dell R920 with 24 x 1.2TB disks (and 1TB RAM), I'm looking to set up a RAID 5 configuration for fast IO. The server will be used to host KVM VMs that will be reading/writing files of all sizes, ...
5
votes
3answers
490 views

Should I host my entire web application using https?

Actually my only requirement for using SSL encryption is that when a user logs in, the password is transferred encrypted. However after reading a bit about protocol switching, that an HTTPS session ...
5
votes
6answers
601 views

Sysadmin performance metrics?

I work at a dot com and part of our team's responsibility is to maintain the production web application and server farm. Only recently did our department even get created, and now we have a huge ...
5
votes
8answers
7k views

Hard Drive Speed: RPM vs. Cache

When trying to choose a SATA magnetic hard drive (not SSD) for high performance for both random and linear access, which should be the primary factor? For example: would a 10k RPM drive with 16MB ...
5
votes
4answers
9k views

Virtual Machine guest optimization tips

I've installed Windows7 in VirtualBox 2.2.4 and worked like a charm. But compared with my WindowsXP virtual machine, the performance is slow. I've installed Windows7 in (non-virtual) machines and the ...
5
votes
6answers
862 views

How to do periodic Sql Server performance monitoring and troubleshooting?

What are the best tools and processes for periodically monitoring and troubleshooting sql server performance issues?
5
votes
3answers
22k views

HDD: performance differences between 7.2k SATA and 15k SAS

What is the rule of thumb in performance characteristics and differences between 7200rpm (SATA/SAS) and 15000rpm (SAS) hard disc drives of the same generation?
5
votes
4answers
632 views

Is there an advantage to load balancing using multiple VMs all on the same hardware?

Some collegues are suggesting a web load balancing schema with multiple web servers (IIS7) on different virtual machines all running on the same hardware. Is this a truly advantageous setup? All ...
5
votes
8answers
8k views

Windows app to monitor Linux server load, etc of a remote server in real time? [closed]

Is there a desktop app (for Windows preferably) that will connect to a remote Linux server, and provide a realtime meter/history graph of the server load and other metrics on that remote server? ...
5
votes
2answers
6k views

Clustered indexes versus non-clustered indexes?

I am in charge of a smaller DB 300+ hundred megs 100'ish tables about 45 users hit it throughout the work day. Mostly reads, but a fair number of updates and inserts. I have been slowing learning the ...
5
votes
4answers
3k views

dd vs. secure-erase for reconditiong SSDs

Does writing zeros to an entire ssd (dd if=/dev/zero of/dev/sdX) give the same performance restoring effect that you get from a "secure erase", or does secure erase do something else as well? ...