Re: SAS Raid - mfi driver

Solved my issue with LSI 8480E without BBU. With "write: BadBBU",
"cache: enabled", and "io: cached", performance rose to around 200MB/s
from 20MB/s.

With BadBBU/enabled cache/io cached:
[root@ ~/bench]# ./bench /dev/mfid0p1 65536
file /dev/mfid0p1, bs 65536
rate: 228130816 Bps, write: 285 us
rate: 206635008 Bps, write: 299 us
rate: 206372864 Bps, write: 305 us
rate: 206438400 Bps, write: 307 us
...

With Write through:
[root@ ~/bench]# ./bench /dev/mfid0p1 65536
file /dev/mfid0p1, bs 65536
rate: 40763392 Bps, write: 1609 us
rate: 19202048 Bps, write: 2260 us
rate: 25231360 Bps, write: 2301 us
rate: 19660800 Bps, write: 2418 us
...

10x performance win, so this is one thing off my back.

Kind regards,
Fredrik Widlund

Fredrik Widlund wrote:
256MB cache, no BBU. Tried a lot of different combinations of settings.

fbsd 6.2pre writes 220MB/s with raid-0

If I boot windows server 2003 instead, it writes at around 180MB/s with
raid-5 (same configs).

With fbsd6.2pre, I get the "best" performance with BadBBU/direct
io/disabled cache and 8 drives, maybe around 50 MB/s, however I get a
zig-zag performance pattern, with the adapter running at 500% (gstat)
utilization one second, then down to 0% for maybe 3 seconds, back, etc.

Fredrik

Ivan Voras wrote:

Fredrik Widlund wrote:

Ivan Voras wrote:

Several:

- are there cache differences between the controllers (amount of
memory, cache policy)?

Default settings on both.

Maybe you should check what the defaults are :) Especially the amount
of memory and is there a battery to back the cache.


- how does writing directly to the device (bypassing file system)
compare?

Drives are four seagate 7200.10 400GB in a Raid-5 configuration.

[/mnt/test (/dev/mfid0p1 mounted)]
read: 200MB/s
write: 15MB/s

[/dev/mfid0p1]
read: 200MB/s
write: 8MB/s

[/dev/mfid0]
read: 200MB/s
write: 10MB/s

This is bad :( The difference between p0 and raw device might indicate
a stripe size misalignment, but the values are too low in any case.


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