Unable to start new processes

Chris MacDonald chris at fourthandvine.com
Fri Nov 5 02:17:41 UTC 2010


On Thu, Nov 4, 2010 at 6:44 PM, Rashkae <ubuntu at tigershaunt.com> wrote:
> On 10-11-04 08:20 PM, Chris MacDonald wrote:
>> Ok, sorry for the absolutely horrendous delay, but I've finally got a
>> few test machines set up to hopefully solve this.
>>
>> See my original post for a description of the problem, it still
>> applies. I'm seeing this problem on multiple instances of the same
>> hardware. The machines are all D510MOs with 1GB of ram and a 4GB USB
>> flash drive that is host to Ubuntu, previously 10.04, but now 10.10
>> and the errors persist. I captured the error (pasted below) over the
>> serial port, but I'd seen it once before and it occurred at a
>> different sector. I've restarted the machine and I'm sure it will
>> crash again within a day or two. I'm also setting up another machine,
>> exact same hardware, I'll see if that fails too.
>>
>> I'm starting to think this is a systemic hardware fault somewhere, but
>> if anyone knows their kernel debug-fu I'd be happy to give something a
>> try at my end to hopefully narrow the focus a bit.
>>
>> [266929.048995] end_request: I/O error, dev sda, sector 776208
>> [266929.065740] Buffer I/O error on device sda1, logical block 96770
>> [266929.084033] Buffer I/O error on device sda1, logical block 96771
>> [266929.102321] Buffer I/O error on device sda1, logical block 96772
>> [266929.120692] end_request: I/O error, dev sda, sector 3490352
>>
>
> Well, that there is your error right there.  Theoretically speaking, I
> suppose it's possible that there is some kind of quirk in those
> motherboards that, combined with Linux USB drivers, gets data errors
> when reading/writing to the Memory sticks.
>
>
> However, given the reproducible nature of your troubles, I think I can
> take the error message at face value,,, when faced with the demands of
> hosting a constant use filesystem, sectors of your flash ram are simply
> getting worn out.  As a rule of thumb, USB flash drives are cheap simple
> devices, unlike hard drives, or even SSD drives, they have neither wear
> level algorithms nor error correction.  It's not all surprising if you
> have a batch of them that, after hundreds, if not thousands of rewrites
> to the same sectors eventually start generating errors.
>
> Keep in mind that, if you do not specify noatime in the filesystem mount
> options, files which are accessed constantly are also getting their
> 'access time' constantly updated.  And on a Journaled filesystem, those
> meta-data updates generate even more io for the journaling.  This is not
> the the kind of use Flash Drives are meant to be put too.
>
>
>
>
>
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>

Apologies for top-posting. I keep forgetting about that here... it's
one of the few places I've seen it 'enforced'.

I'll set up a machine running with noatime and see how it compares to
the others. If it's indeed a problem with bad sectors then I would
expect the error to be less frequent, if it should occur at all.

I should have mentioned the flash drives again in my more recent post,
they're these:

http://www.micron.com/products/solid_state_storage/eusb.html

or more specifically

http://www.micron.com/document_download/?documentId=575

I wasn't involved in procurement but anything I read there leads me to
believe they're ok for use as an OS drive and employ some manner of
both error correction and wear levelling. However, a trip to Micron's
website has made me aware of an app they have for pulling bad block
count information off the module; I'll contact them and see where that
takes me.

Thanks for the input all, this has given me a few more things to try.

Chris




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