how would one use these statistics to diagnose how to improve raid
performance??
hdparm -t -T /dev/md1
/dev/md1:
Timing buffer-cache reads: 64MB in 1.36 seconds =47.06 MB/sec
Timing buffered disk reads: 32 MB in 4.01 seconds = 7.98MB/sec
Seeker 1...Seeker 2...Seeker 3...start 'em...done...done...done...
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
100 3562 92.2 11899 47.4 4631 32.2 2576 64.3 10543 26.3
153.7 3.6
> > Here are a pair of 7200rpm Seagate IDE drives as RAID0, using UDMA0:
> >
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
100 16017 89.3 85390 82.6 10960 29.0 14436 66.5 18679 19.3
760.1 4.2
> >
> > Most of the speed difference is probably due to a faster CPU
(P2-400).
>
> I have a Celeron 333, which should not be dramatically slower. Are
> you sure these numbers are right -- 85 MB/s? How much RAM is in that
> machine?
Not meant to deny those results, but I've had different (read slower)
results on a 256MB SMP P2-300 box with a SCSI Symbios 896 Fast-40 (using
Roudier's pre-sym53c8xx-0.16 driver). Controller on a RAID0 subsystem
made
of 2 Seagate Barracuda (7200rpm as well) LVD Ultra2s (80MB/s).
(running 2.1.130 with the latest RAID patch)
# hdparm -t -T /dev/md0
/dev/md0:
Timing buffer-cache reads: 64 MB in 0.81 seconds =79.01 MB/sec
Timing buffered disk reads: 32 MB in 1.13 seconds =28.32 MB/sec
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
100 11829 95.0 41633 93.9 20024 69.2 14727 98.4 178219 99.2 8626.6 196.3
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
768 10482 88.5 23845 63.0 6914 32.2 12429 80.8 28101 54.0 203.9 4.9
Cheers!
--
P(eace)L(ove)U(nity)R(espect),
Bill
----
"Do not meddle in the affairs of Unix wizards, for
you are crunchy and good with ketchup, and i am a wizard."
