SAS Raid - mfi driver

[Scott Long]

As I said in private email, you need the battery in order to restore
performance.  Linux and Windows get by because they can send larger
I/O's to the controller than FreeBSD can.  The larger I/O's aren't
terribly useful for most real-world applications, though.

Scott


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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