[Beowulf] mysterious slow disk
Bogdan.Costescu at iwr.uni-heidelberg.de
Wed Mar 5 07:00:30 PST 2008
On Thu, 6 Mar 2008, csamuel at vpac.org wrote:
> If the problem moves with the drive then you'll know it's that, and
> if it stays then it's likely to be the MB or the cabling.
Sorry for the late jump...
IIRC, the OP had dual Athlon based nodes; there used to be some issues
of slow I/O related to the usage of energy saving features of the CPUs
and/or chipset. Have you already checked for such a situation ?
Another thing that comes to my mind: I have seen some SATA disks (I
think from Hitachi) which have developed some bad sectors, which could
be seen in the smartctl output. I have run the DFT on them and after
choosing to rewrite the whole disk (I have forgotten the exact option
name...) the disk was shown as good and there was no sign of bad
sectors in the smartctl output. However, the access to disk was
slower, especially the writes, for which the speed was aproximately
halved. So, is it sure that the disk was never subjected to a
manufacturer "diagnose and repair" tool ?
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E-mail: bogdan.costescu at iwr.uni-heidelberg.de
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