On Tue, 2010-01-12 at 17:00 -0600, Tim Nelson wrote:
> Greetings all-
>
> I'm on a quest to do some serious tuning to some of my production systems.
> All are on CentOS 5.x ranging from 5.0 to 5.4. I've been reading up on the
> various IO schedulers available in the kernel and I'm hoping some of you can
> lend some insightful suggestions. I typically have three classes of system in
> production:
>
> 1. Storage/DB - Backend nodes for the application servers, MySQL, NFS storage
> serving to frontend nodes (deadline?)
> 2. Web/SSL - Frontend nodes serving up web application (PHP/MYSQL), heavy SSL
> {en/de}cryption with both HTTPS/Apache as well as branch locations connecting
> via OpenVPN (cfq?)
> 3. Telephony/Communications - VoIP, usually Asterisk (full signaling + media
> services), massive context switching, very timing sensitive (Meetme
> conferencing, IAX2 trunk mode, etc) (deadline?)
>
> In my reading, I've found most people recommend deadline for DB intensive
> systems. CFQ seems to be recommended for most other uses. Noop and as seem to
> be irrelevant. Is this correct or am I way off base?
You cant go by that. What works for them prolly want work for you.
> I'm not currently under any enormous load on any of these systems, but I'm
> planning for growth and would like to see how different schedulers can make a
> difference.
>
> I welcome your suggestions and experiences. :-)
>
> --Tim
---
What is "nr _requests" for your DB Servers, honest you need many many
writes for this.
cat /sys/block/sda/queue/nr_requests
Really to be honest with you every machine is different, even if you
have 2 IBM pServers with the same harware. I don't have any mysql
servers but I do run IBM DB2 with "nr_request @ almost 10000. Not to
mention you could also tune your TCP/IP stack also. Also using blockdev
to tune the disks.
No one really tell you exactly what you need. BTW I have seen mysql
running @ a rate of over 10000 on nr_request. Takes a bit of high end
hardware.
John
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