How to reduce IOWAIT in linux - UNIX for Advanced & Expert Users

bache_gowda · #1 07-13-2007

Hi All,

Any ideas how to reduce IOWAIT and increase disk speed on Linux server.

Server has 4 CPUs and with 8GB RAM.

Thanks in advance,

Regards,
Bache

porter · #2 07-13-2007

Not knowing much about your machine here are a few thoughts.

1. Are you using the fastest disks you can, both rotational speed and transfer speed and can your disk controllers support the transfer rates?

2. Consider having a number of disks so binaries live on different disks to data. This will reduce the time spent waiting for seeks to occur.

3. In certain configurations, a RAID arrangement may speed up access to disks.

4, Are you using delayed writes?

porter · #3 07-14-2007

Here is an interesting article regarding performance tweaks for Linux...

http://www.linux.com/feature/116693

Quote:

The hdparm command ("hdparm" stands for "hard disk parameters") allows you to examine and modify drive configuration. Not all modifications are good: some will lower the performance, and some can even be wildly destructive, leading to data loss. The man hdparm command shows you all the options, and highlights the dangerous ones.

sysgate · #4 07-16-2007

Another tool that will suggest good options is "iozone - filesystem benchmark tool".

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