Dell Perc 5/i Performance issues

Garrett Cooper yanefbsd at
Sat Jun 19 11:32:45 UTC 2010

On Sat, Jun 19, 2010 at 4:24 AM, Garrett Cooper <yanefbsd at> wrote:
> On Sat, Jun 19, 2010 at 4:21 AM, oizs <oizs at> wrote:
>> Since I tested it on different kind of os's, and with at least 5 testing
>> applications, I don't think that would be the case.
>> On 2010.06.19. 13:17, Garrett Cooper wrote:
>>> On Sat, Jun 19, 2010 at 2:58 AM, oizs<oizs at>  wrote:
>>>> I tried almost everything raid 0 1 5 10 with all kind of stripes
>>>> 32/64/128
>>>> and settings direct io/cached/read-ahead/wt/wb/disk-cache but nothing
>>>> seems
>>>> to work.
>>>> I changed the card to another dell perc 5 which had an older firmware.
>>>> Tried
>>>> 4 kind of motherboards even tried changing the os to linux and windows
>>>> xp/7.
>>>> In windows I got some funny results 1.3MB/s with write-back and 150MB/s
>>>> reads with 5 disks in raid0.
>>>> I just wanted to have a hw raid with no problems since the motherboard
>>>> 88sx7042 and bsd did not like eachother.
>>>> On 2010.06.19. 11:07, Svein Skogen (Listmail Account) wrote:
>>>>> On 18.06.2010 01:50, oizs wrote:
>>>>>> Hi,
>>>>>> I've bought a Dell Perc 5/i because I couldn't make the onboard marvell
>>>>>> 88sx7042 work with 8.0/8.1 or current, but as lucky as I am, the best I
>>>>>> can do with 4x1.5tb samsung in raid5 is 60MB/s writes and 90MB/s reads,
>>>>>> with bbu/write-back/adaptive-read-ahead.
>>>>>> I was expecting at least twice of that, and I'm not sure what can I do
>>>>>> to get that speed. (I've read man 7 tuning with no success)
>>>>>> As far as I know this controller should be as fast as on other systems.
>>>>>> ( mx1 has one of these cards.)
>>>>>> I'm hoping somebody on the list reads this and helps because I can't
>>>>>> afford to buy another card.
>>>>> I've lost track of what actual boards Dell has OEMized to make the
>>>>> various PERCs, but if I remember somewhat correctly, the PERC5 is
>>>>> basically an LSI Megaraid SAS 8308elp with different labels and
>>>>> firmware?
>>>>> If so, I've got that exact controller (minus the dell labels and
>>>>> firmware) in my primary storage box here, and yes, you SHOULD be able to
>>>>> get more performance out of it. What's your strip sizes and logical disk
>>>>> layout?
>>>>> (I've got the same board running on 8x 1T5 Seagates in RAID5+0, and that
>>>>> setup easily pulls 5 times the values you're seeing, and by all logic
>>>>> you should see about half of what I'm seeing)
>>> Dumb question: are you sure that the problem that you're seeing isn't
>>> in fact inhibited by the application that you're getting `performance'
>>> results with?
> If your applications aren't well suited for your hardware's
> capabilities, then of course performance will be bad.

Furthermore, if the performance applications and your use scenarios
are centered around reading, as opposed to writing, there is an option
within mficontrol and the mfi(4) interface where you can actually
enable read-ahead, instead of writeback (you unfortunately can't
enable both scenarios). I realize that this is an artificial
improvement in a way, but you should judge whether or not your
application will be doing more reading than writing in whatever
capacity it's doing...


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