On 15/09/2010 10:07 PM, Tom Lane wrote:
>> The server is from Dell, Dell's hardware monitoring, OpenManage, says that the hardware, in particular memory and
disk,are ok.
>
> Never dealt with OpenManage before, but you should cast a wary eye
> upon any Dell-specific software on the machine.
(A bit of a digression, but):
Personally I'd suggest being wary of any software supplied by the entity
that will be responsible for the costs of any warranty work. They won't
be at *all* sad if their software deflects blame and you don't discover
a fault until your server is out of warranty.
I've seen enough HDD vendor utilities report that a disk is just peachy,
thanks, when it's developing and reallocating bad sectors at a rate of
one every few minutes. ("Hey, you didn't need that boot block, I've
allocated you a shiny new one full of zeroes that's just as good.") The
S.M.A.R.T. "health check" tends to say everything's fine, too ... but if
you examine the fine print in the vendor attributes you see very high
reallocated sector counts, ECC error levels, and other signs of a dying
disk. I see this with so-called "enterprise" disks, not just consumer
SATA drives.
HDD vendors are certainly a particularly bad case, but nonetheless -
don't trust vendor diagnostic software in general. If it says the device
is broken I'll believe it because I trust them to make sure it won't
report expensive false positives - but if it says it's OK I'll merely
consider it not proven broken yet. False negatives work in their favour.
Find 3rd party diagnostic tools where possible, and where not possible
don't trust the overall health assessment provided by the vendor tools,
dig into the fine print in the diagnostics and see what the details are
like.
For hard disks, smartctl from smartmontools is a lifesaver. Your issue
doesn't sound HDD related, but it's worth mentioning for the future.
--
Craig Ringer
Tech-related writing at http://soapyfrogs.blogspot.com/
