> - What kinds of numbers are you getting for performance now?
Kinda hard to say, we're far more interested in random IO rather
than sequential stuff.
> and do a make and then ./tiobench.pl --threads 16
/tiotest/ is a single root disk
/data1 is the 8 disc raid 1+0
/data2 is the 3 disc raid 5
All discs are IBM DMVS18D so 18Gb 10k rpm 2mb cache, sca2 discs.
http://www.storage.ibm.com/hardsoft/diskdrdl/prod/us18lzx36zx.htm
Machine Directory Size(MB) BlkSz Threads Read Write Seeks
----------- ----------- --------- ------- --------- ------ ------- -------
/tiotest/ 512 4096 1 18.092 6.053 2116.40
/tiotest/ 512 4096 2 16.363 5.792 829.876
/tiotest/ 512 4096 4 17.164 5.882 1520.91
/tiotest/ 512 4096 8 14.533 5.852 932.401
/tiotest/ 512 4096 16 16.244 5.806 1731.60
/data1/tiot 512 4096 1 29.257 14.406 2234.63
/data1/tiot 512 4096 2 38.124 13.734 1111.11
/data1/tiot 512 4096 4 31.373 12.864 5128.20
/data1/tiot 512 4096 8 29.341 12.460 4705.88
/data1/tiot 512 4096 16 34.806 12.121 5555.55
/data2/tiot 512 4096 1 23.063 16.269 1851.85
/data2/tiot 512 4096 2 21.576 16.754 1498.12
/data2/tiot 512 4096 4 17.908 17.021 3125.00
/data2/tiot 512 4096 8 15.773 17.107 3478.26
/data2/tiot 512 4096 16 15.394 16.920 4166.66
> - 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?
6 discs on each channel, discs 1-4 of each pack form the raid 6 stripe,
discs 5 and 6 on ch1 and 5 on ch2 are in the raid5, disc 6 on ch6 is the
spare.
> - Is the card using its write cache? write-back or write-through?
Its using write back on both devices.
> - Do you have the latest firmware on the card?
Pretty much, the firmware changelog implies the only real change
is to support PCI hotswap.
> - Which kernel are you using?
Standard Redhat 6.1 kernel
Linux xxx.yyy.zzz 2.2.12-20smp #1 SMP Mon Sep 27 10:34:45 EDT 1999 i686 unknown
> - What block size is the filesystem? Did you create with a -R param?
4k blocksize, didn't use the -R as this is currently hardware raid
> - What is your percentage of I/O operations that are writes?
Approx 50%
>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 :)
Can't fault your logic there... But don't you mean 0+1 ie 2 stripes
of 6 discs mirrored together rather than 1+0 (6 mirroring pairs striped
together).
>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)
Which would you like me to try all software or do part in software
and part in hardware and if the latter which part? The raid card
seems pretty good (233MHz strongarm onboard) so I doubt that is limiting
us.
thanks,
Chris
--
Chris Good - Dialog Corp. The Westbrook Centre, Milton Rd, Cambridge UK
Phone: 01223 715000 Fax: 01223 715001 http://www.dialog.com
