Re: High iowait

[email protected] wrote:
> Basically i am not able to achieve the kind of throughput which i
> should get from my RAID system. And i think the OS is the culprit
> (some bug in the vendor kernel) since for some reason it goes into
> huge iowaits preventing the applications to read/write more data. How
> can i debug whether the problem is with the OS or with the device?
>

#1 Problem usually: Is DMA enabled? (see hdparm refs)...

RAID FAQ & Docs...
http://www.faqs.org/contrib/linux-raid/x37.html
http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/sysadmin-guide/ch-raid-intro.html
http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch26_:_Linux_Software_RAID
http://www.tldp.org/HOWTO/Software-RAID-HOWTO.html

mdadm - tool for managing Linux Software RAID arrays
http://neil.brown.name/blog/mdadm

Benchmarking RAID configurations
http://www.catux.org/index.php?contingut=articles&num=101
http://www.acnc.com/benchmarks.html
http://www.coker.com.au/bonnie++/
http://www.iozone.org/
http://www.sourcepole.com/sources/reviews/raid/bottom.html

HOWTO Use hdparm to improve IDE device performance - GentooWiki
http://gentoo-wiki.com/HOWTO_Use_hdparm_to_improve_IDE_device_performance
HDparm - Tuning up your IDE hard disks using hdparm.
http://usalug.org/phpBB2/viewtopic.php?p=33142

-GL Art@JAX

--
Art Wildman - NWS JAX FL. - http://www.srh.noaa.gov/jax
"If you choose not to decide, you still have made a choice" -Rush|Freewill