At 11:48 AM -0500 1999/12/16, David Gilbert wrote:
> It's a really long thread. I'm not going to repeat it here.
> Basically, under "enough" load, vinum trashes the kernel stack in such
> a way that debugging is very tough.
It sounds like the second RAID-5 bug listed on the page I mentioned:
>> 28 September 1999: We have seen hangs when perform heavy I/O to
>> RAID-5 plexes. The symptoms are that processes hang waiting on
>> vrlock and flswai. Use ps lax to display this information.
>>
>> Technical explanation: A deadlock arose between code locking stripes
>> on a RAID-5 plex (vrlock) and code waiting for buffers to be freed
>> (flswai).
>>
>> Status: Being fixed.
I believe that I have seen this bug myself, but in my only
serious attempt to replicate it, I managed to create what appears to
be a new third bug which he had never seen before. Yes, I've already
given all debugging information to Greg.
> I got the MegaRAID 1400 because the DPT V drivers weren't available.
Understandable. I didn't know that the AMI MegaRAID controller
was even an option, otherwise I would have looked at it.
> The MegaRAID should be roughly equivlanet to the DPT V.
I'd really like to see these two benchmarked head-to-head, or at
least under sufficiently similar circumstances that we can be
reasonably comfortable with how well one performs relative to the
other.
> Do go with
> LVD if you can.
The drives are using SCA attachment mechanisms, but I believe
that electronically they are LVD.
> I have done benchmarking with bonnie instead of rawIO. The output is
> as follows:
I have never been impressed with the benchmarking that bonnie is
capable of. In my experience, rawio is a much better tool, because
it handles coordinating large numbers of child processes, doesn't
lose information in communications between the parent and the child
processes, by-passes all the filesystem overhead, etc....
If you want to do filesystem level benchmarking, I've been more
impressed by what I've seen out of Postmark.
--
These are my opinions -- not to be taken as official Skynet policy
____________________________________________________________________
|o| Brad Knowles, <[EMAIL PROTECTED]> Belgacom Skynet NV/SA |o|
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