[wellylug] High load averages but no apparent cause

[Daniel Pittman]

Daniel Reurich <daniel at centurion.net.nz> writes:
> On Thu, 2010-03-25 at 10:31 +1100, Daniel Pittman wrote:
>> David Harrison <david.harrison at stress-free.co.nz> writes:
>> 
>> > No, but now that you say that if the system is unable to write to the RAID5
>> > which contains the log file would this even happen?
>> >
>> > e.g. /var is the problematic RAID5 partition and when it locks up it takes
>> > out one or more of the physical disks.
>> >
>> > An interesting observation is that when the problem occurs it either locks
>> > up both sda & sdb, or sdc by itself.  I am guessing that this is because sda
>> > & sdb are on the same channel, so either the channel itself is going or one
>> > of the disks is which is taking the other with it.
>> 
>> That is extremely unlikely: SATA disks don't have the older PATA "shared
>> channel" issue, and as far as I can tell these are SATA disks, right?
>
> Maybe.  It may well be the the phy's that drive the signals down the sata
> cables typically do pairs of channels, but I'm only speculating here.

Ah.  FWIW, I wasn't.  While I can't speak for all the implementations, none of
the likely SATA implementations y'all will encounter do that.

        Daniel

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