SAS Raid - mfi driver

[Fredrik Widlund]

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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>
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