[ Monday, January 10, 2000 ] [EMAIL PROTECTED] wrote:
> I've currently got a hardware raid system that I'm maxing out so
> any ideas on how to speed it up would be gratefully received.
Just some quick questions for additional info...
- What kinds of numbers are you getting for performance now?
- I'd check bonnie with a filesize of twice your RAM and
then get http://www.icon.fi/~mak/tiotest/tiotest-0.16.tar.gz
and do a make and then ./tiobench.pl --threads 16
- Did you get a chance to benchmark raid 1+0 against 0+1?
- Of the 12 disks over 2 channels, which are in the raid0+1, which
in the raid5, which spare? how are the drive packs configured?
- Is the card using its write cache? write-back or write-through?
- Do you have the latest firmware on the card?
- Which kernel are you using?
- What block size is the filesystem? Did you create with a -R param?
- What is your percentage of I/O operations that are writes?
> Since there is a relatively high proportion of writes a single raid5 set
> seem to be out. The next best thing looks like a mirror but which is going
> to be better performance wise, 6 mirror pairs striped together or mirroring
> 2 stripes of 6 discs?
IMO raid 1+0 for 2 stripes of 6 discs (better be around when a drive goes,
though, as that second failure will have about a 55% chance of taking
out the array :)
> Does the kernel get any scheduling benefit by seeing the discs and doing
> things in software? As you can see the machine has a very low cpu load
> so I'd quite hapily trade some cpu for io throughput...
I'd really love to see you do a s/w raid 1 over 2 6-disk raid0's from
the card and check that performance-wise... I believe putting the raid1
and raid0 logic on sep. processors could help, and worst case it'll
give a nice test case for any read-balancing patches floating around
(although you've noted that you are more write-intensive)
James
--
Miscellaneous Engineer --- IBM Netfinity Performance Development
