Re: I/O Confirmation/Problem under 2.6/2.4
From: comsatcat
Date: Wed Jun 23 2004 - 14:46:05 EST
> Is that peak or saturated load? you may want to try to only fill the write
> back cache of the controller, to not get affected by slow raidness or disks.
>
Saturated, just doing a simple dd out to a 2gig file.
> The raid5 is not very good in speeding up random reads or sequential writes.
> Perhaps you want to try stripping on level 0.
>
We need the data integrity and the storage so 0/1 isn't an option and 0
definantly isn't.
> What is the IO Bus you are talking about? Single PCI Bus?
PCI-x 133MHz (card is running at 66MHz).
> Have you tried an alternative operating system?
>
I've tried Red Hat AS 3 and Gentoo 2004.1
> You may want to try it without a filesystem and perhaps even with a faster
> raid configuration like stripping.
>
Have actually done both for tests. writing to the device w/o FS returns
about the same rate. Raid 0 is a bit faster then 5, but not by more
then a couple of MB.
> how does your vmstat and iostat look like? How many ram and cpu you are
> talking about? is it an smp kernel?
>
Ram is 2GB, CPU is Dual 3.2GHz Xeons hyperthread (thus 4 cpu's to OS),
smp is enabled. iostat is very spotty, here is output from iostat:
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s
avgrq-sz avgqu-sz await svctm %util
rd/c0d0 0.00 84389.83 0.00 0.00 0.00 680576.27 0.00
340288.14 0.00 760.19 0.00 0.00 102.54
rd/c0d0 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 31860.75 0.00 0.00 96.34
rd/c0d0 0.00 38713.00 0.00 0.00 0.00 312152.00 0.00
156076.00 0.00 29827.95 0.00 0.00 100.00
rd/c0d0 0.00 11048.00 0.00 0.00 0.00 89088.00 0.00
44544.00 0.00 13318.73 0.00 0.00 100.00
rd/c0d0 0.00 12948.00 0.00 0.00 0.00 104448.00 0.00
52224.00 0.00 13405.94 0.00 0.00 100.00
rd/c0d0 0.00 9344.00 0.00 0.00 0.00 75360.00 0.00
37680.00 0.00 13488.18 0.00 0.00 100.00
rd/c0d0 0.00 9178.00 0.00 0.00 0.00 74032.00 0.00
37016.00 0.00 29379.11 0.00 0.00 100.00
rd/c0d0 0.00 12962.00 0.00 0.00 0.00 104560.00 0.00
52280.00 0.00 13653.53 0.00 0.00 100.00
rd/c0d0 0.00 9363.00 0.00 0.00 0.00 75512.00 0.00
37756.00 0.00 13737.13 0.00 0.00 100.00
rd/c0d0 0.00 11321.00 0.00 0.00 0.00 91288.00 0.00
45644.00 0.00 29128.95 0.00 0.00 100.00
rd/c0d0 0.00 9902.00 0.00 0.00 0.00 79872.00 0.00
39936.00 0.00 13901.66 0.00 0.00 100.00
rd/c0d0 0.00 10140.00 0.00 0.00 0.00 81784.00 0.00
40892.00 0.00 13984.07 0.00 0.00 100.00
rd/c0d0 0.00 8773.00 0.00 0.00 0.00 70768.00 0.00
35384.00 0.00 28883.74 0.00 0.00 100.00
rd/c0d0 0.00 13709.00 0.00 0.00 0.00 110592.00 0.00
55296.00 0.00 14150.42 0.00 0.00 100.00
rd/c0d0 0.00 10143.00 0.00 0.00 0.00 81808.00 0.00
40904.00 0.00 14240.10 0.00 0.00 100.00
rd/c0d0 0.00 11047.00 0.00 0.00 0.00 89088.00 0.00
44544.00 0.00 28629.28 0.00 0.00 100.00
rd/c0d0 0.00 10790.00 0.00 0.00 0.00 87040.00 0.00
43520.00 0.00 14403.05 0.00 0.00 100.00
And here is vmstat output:
procs memory swap io
system cpu
1 1 0 833460 33768 595768 0 0 0 459360 160 371 0
51 49 0
0 3 0 668604 33928 759864 0 0 0 35196 140 31 0 30
10 60
1 2 0 611132 33980 813932 0 0 0 54944 160 48 0
13 3 84
0 3 0 568668 34016 851236 0 0 0 43520 143 54 0
7 0 93
0 3 0 534652 34056 888740 0 0 0 40448 145 60 0
7 0 93
1 2 0 473476 34096 933548 0 0 0 56320 145 73 0
9 0 91
0 3 0 445868 34132 970332 0 0 0 32256 139 56 0
6 0 94
0 3 0 396756 34176 1015048 0 0 0 43520 142 60 0
8 0 92
0 3 0 352124 34220 1059988 0 0 0 44700 145 54 0
9 0 91
2 1 0 308348 34264 1101852 0 0 0 50140 139 70 0
8 0 92
0 3 0 253488 34312 1153080 0 0 0 42272 140 63 0
10 0 90
0 3 0 228168 34344 1185468 0 0 0 31848 142 54 0
6 0 94
0 3 0 190080 34384 1225076 0 0 0 40856 140 57 0
8 0 92
1 2 0 130820 34428 1271444 0 0 0 55912 138 71 0
9 0 91
0 3 0 90352 34468 1313104 0 0 0 35328 140 57 0
11 2 88
1 2 0 65652 34540 1375600 0 0 0 47772 146 61 0
10 0 90
0 4 0 58060 34580 1416852 0 0 0 37280 142 41 0
9 0 91
0 4 0 100292 34580 1416852 0 0 0 36496 139 57 0
1 0 98
0 3 0 145160 34580 1416852 0 0 0 55248 141 18 0
1 49 50
0 3 0 187804 34580 1416852 0 0 0 40960 143 14 0
1 50 49
Thanks,
Ben
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