Re: xfs > md 50% write performance drop on .30+ kernel?

[mark delfman <markdelfman@googlemail.com>]

PS - LSI havent publically released the SAS2 (non-raid) card as yet.
They have just released the RAID version and will follow with the
non-raid soon.

Their chips are being used on some of the later server motherboards,
so SAS2 is around but new.



On Tue, Oct 13, 2009 at 4:13 PM, mark delfman
<markdelfman@googlemail.com> wrote:
> We dont use 10 ports, we use 8 ports > 36 port expander. The 8 ports
> act as a single wide port.
>
> We are hitting a performance limit of circa 1.6 - 1.9GBsec regardless
> of number of drives, so it max's at around 8 / 9 drives (with 15K).
> RAID6 around 900MBsec i recall.  We expect more with emerging
> expanders.
>
> We were hoping to use DM MPIO to increase performance using multiple
> cards and paths, but MPIO at best matches performance of a single
> card, most likely pulls it down.... but this is a different topic i
> guess.
>
> XFS in the past has often increased performance - not allows on simple
> sequential writes, but FS's are a lot better at intelligently caching
> data... so I am very keen to help in whatever way i can to resolve the
> FS > MD performance problem.
>
> Thanks again.... Mark
>
>
> On Tue, Oct 13, 2009 at 3:30 PM, Asdo <asdo@shiftmail.org> wrote:
>>
>>> On Tue, Oct 13, 2009 at 2:12 PM, mark delfman
>>> <markdelfman@googlemail.com> wrote:
>>>
>>>>
>>>> We upgrading mainly because of support for the emerging LSI SAS2 cards
>>>> (which we are beta testing now)
>>>>
>>
>> What is this LSI SAS2 card you have with 10+ ports? The only 10+ ports LSI
>> card I see is the 84016E and it is a SAS1.
>>
>> You say the driver for such card is included in the vanilla kernel at
>> 2.6.30? That would be very nice... I grepped the 2.6.31 kernel source for
>> LSI cards but I can't find device strings such as 84016E ...
>>
>> Thank you
>>
>
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