[ale] who is eating my drive

[Jim Kinney]

On Tue, May 31, 2011 at 5:49 PM, Greg Clifton <gccfof5 at gmail.com> wrote:

> Obviously, if any of the remaining RAID member disks had a non-recoverable
> read, the swap would be hosed, but I was just thinking that if it was
> marginally readable and the disc had to make several read attempts to get a
> good read, the time required for that process could cause a time out, even
> though the data could be recovered with DD or such.


That sounds plausible. Send itto  Mythbusters!

>
> On Tue, May 31, 2011 at 5:38 PM, Jim Kinney <jim.kinney at gmail.com> wrote:
>
>>
>>
>> On Tue, May 31, 2011 at 4:13 PM, Greg Clifton <gccfof5 at gmail.com> wrote:
>>
>>> I have no direct experience in the matter, but I would expect that there
>>> could well be a problem during the rebuild when (not if) there is a block of
>>> data that is difficult, but still possible, to read on one of the RAID
>>> members. Seems the retries could cause the no swap panic. No?
>>
>>
>> definate maybe. The failed drive was out so it was rebuilding off teh
>> remaining 2. A second drive could have lost a block as well.
>>
>>>
>>> GC
>>>
>>>
>>> On Tue, May 31, 2011 at 4:00 PM, Jim Kinney <jim.kinney at gmail.com>wrote:
>>>
>>>>
>>>>
>>>> On Tue, May 31, 2011 at 3:45 PM, Pat Regan <thehead at patshead.com>wrote:
>>>>
>>>>> On Tue, 31 May 2011 15:34:05 -0400
>>>>> Jim Kinney <jim.kinney at gmail.com> wrote:
>>>>>
>>>>> > On Tue, May 31, 2011 at 3:04 PM, Pat Regan <thehead at patshead.com>
>>>>> > wrote:
>>>>> >
>>>>> > > On Tue, 31 May 2011 14:49:53 -0400
>>>>> > > Jim Kinney <jim.kinney at gmail.com> wrote:
>>>>> > >
>>>>> > > > swap notes: NEVER put swap on a raid5. If you must park swap on a
>>>>> > > > RAID rig, mirrored partitions are OK. If swap gets hosed, the box
>>>>> > > > crashes. The RAID5/6 writes for swap are performance killers.
>>>>> Swap
>>>>> > > > will do it own striping so don't bother doing a raid10. multiple
>>>>> > > > swap parts on multiple drive spindles is a good thing. Say 8G RAM
>>>>> > > > and 4 1TB drives, set up a 4G swap on each of the drives.
>>>>> > >
>>>>> > > Putting swap on RAID also means that your server won't go down due
>>>>> > > to a disk failure.
>>>>> > >
>>>>> >
>>>>> > Swap on RAID5/6 means during a rebuild the disk IO times out on swap
>>>>> > retrieval and the kernel panics thinking the swap is down.
>>>>>
>>>>> I have never had this happen, although I can only recall one time that
>>>>> I've ever had swap on a RAID 5.  It was a hardware RAID 5 and was the
>>>>> only disk available.
>>>>>
>>>>> Is this only a problem with software RAID?  I'd be surprised if it
>>>>> is...
>>>>>
>>>>> In your experience with this situation, where exactly is the timeout
>>>>> happening?
>>>>>
>>>>
>>>> Saw this fail once a while back. swap on a hardware raid5 that lost a
>>>> drive. the last line on the screen before the lockup was
>>>> kernel panic swap error
>>>> after the dead drive was replaced (hot swap setup) and the system was
>>>> still running during the recovery.
>>>>
>>>> OK. So maybe the hardware could detect I'm no fan of RAID5 in any form
>>>> and dislike hardware in most forms and just decided to take a dump because I
>>>> was standing there.
>>>>
>>>>>
>>>>> Pat
>>>>> _______________________________________________
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>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> --
>>>> James P. Kinney III
>>>>
>>>> As long as the general population is passive, apathetic, diverted to
>>>> consumerism or hatred of the vulnerable, then the powerful can do as they
>>>> please, and those who survive will be left to contemplate the outcome.
>>>> - *2011 Noam Chomsky*
>>>>
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>>>>
>>>
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>>
>>
>> --
>> --
>> James P. Kinney III
>>
>> As long as the general population is passive, apathetic, diverted to
>> consumerism or hatred of the vulnerable, then the powerful can do as they
>> please, and those who survive will be left to contemplate the outcome.
>> - *2011 Noam Chomsky*
>>
>> _______________________________________________
>> Ale mailing list
>> Ale at ale.org
>> http://mail.ale.org/mailman/listinfo/ale
>> See JOBS, ANNOUNCE and SCHOOLS lists at
>> http://mail.ale.org/mailman/listinfo
>>
>>
>
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>


-- 
-- 
James P. Kinney III

As long as the general population is passive, apathetic, diverted to
consumerism or hatred of the vulnerable, then the powerful can do as they
please, and those who survive will be left to contemplate the outcome.
- *2011 Noam Chomsky*
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