Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> writes:
> Have you tried a 1024k stripe and 16384k stripe_cache_size?
>
> I'd be curious what kind of performance/write speed you get with that
> configuration.
>
> Justin.
stripe_cache_size is not in KiB of memory but in multiples of some
internal structures. So 16384 * 4 raids is ~1.6GB ram. We only have
2GB ram in the system so this is very near an OOM just for the stripe
cache:
Mem: 2062468k total, 1735048k used, 327420k free, 4096k buffer
Swap: 0k total, 0k used, 0k free, 9924k cached
1 Thread:
9442 root 16 0 0 0 0 R 73 0.0 3:33.89 pdflush
9590 root 10 -5 0 0 0 S 57 0.0 1:29.73 md0_raid5
9747 root 25 0 28364 1392 184 R 85 0.1 1:06.09 iozone
257 root 10 -5 0 0 0 D 23 0.0 4:47.50 kswapd1
256 root 10 -5 0 0 0 S 12 0.0 4:11.17 kswapd0
2 Threads:
257 root 11 -5 0 0 0 D 27 0.0 4:55.46 kswapd1
9442 root 16 0 0 0 0 S 23 0.0 4:49.65 pdflush
256 root 10 -5 0 0 0 S 9 0.0 4:26.57 kswapd0
9590 root 10 -5 0 0 0 R 40 0.0 2:36.91 md0_raid5
9596 root 10 -5 0 0 0 S 35 0.0 0:50.62 md1_raid5
9487 root 15 0 0 0 0 S 35 0.0 0:37.14 pdflush
9759 root 18 0 28360 1420 216 R 59 0.1 0:11.61 iozone
9758 root 18 0 28360 1420 216 R 70 0.1 0:10.17 iozone
With 4 raid5s:
write rewrite read reread
1 Thread : 193887 196092 365965 401978 <-- use 1 raid5
2 Threads: 221221 255069 430061 365904 <-- use 2 raid5
4 Threads: 238220 257221 395603 409954 <-- use 4 raid5
With just 1 raid5 (and more free mem):
2 Threads:
9590 root 10 -5 0 0 0 R 93 0.0 7:45.04 md0_raid5
9487 root 16 0 0 0 0 S 27 0.0 5:13.43 pdflush
257 root 10 -5 0 0 0 S 5 0.0 6:28.48 kswapd1
256 root 10 -5 0 0 0 S 5 0.0 5:33.40 kswapd0
9818 root 18 0 28364 1416 208 R 56 0.1 0:47.70 iozone
9819 root 18 0 28364 1416 208 D 62 0.1 0:46.58 iozone
write rewrite read reread
1 Thread : 206299 201120 400244 390185
2 Threads: 210888 202785 411502 400532
4 Threads: 200829 145307 400252 395568
MfG
Goswin
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