Re: Miserable Disks
- From: "Jared Still" <jkstill@xxxxxxxxx>
- To: pythianbrinsmead@xxxxxxxxx
- Date: Fri, 26 May 2006 10:22:51 -0700
Comments inline.
On 5/25/06, Mark Brinsmead <pythianbrinsmead@xxxxxxxxx> wrote:
(*) Make your RAID stripe width really narrow (like maybe 128 or 512
bytes) and then
make your database blocks large (like 8KB or 16KB) and do lots of
multi-block I/O,
so that every I/O is assured to engage every physical drive. (Kiss
concurrency goodbye
and watch your RIOPs numbers plummet)
Seems like somthing like this might be optimal for single session.
Benchmarks? ;)
(*) Get the biggest cache you can afford. (Make sure it's *really*
non-volatile. Wolfgang
never mentioned what happens to your database when you lose the contents
of the write
cache, but *I* got a taste! And it wasn't pleasant!)
Yes, I had experience with that 2 weeks ago on a CX700.
Definitely unpleasant.
EMC claimed that we should have disable the write cache
prior to powering down the SAN.
I have since learned that the support tech in question was blowing smoke.
--
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist
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