Re: devices get kicked from RAID about once a month

[Dan Christensen <jdc@uwo.ca>]

Bill Davidsen <davidsen@tmr.com> writes:

> Those logs don't show any information useful to me which tells me how
> long md waited, and I'm not able to parse any of the res: information
> to gain clarity. It would be nice if someone can parse that, but I
> can't. On timeout an elapsed time output would be nice to indicate
> what the time limit is.

I agree.  It would also be nice to know whether there was in fact a read
error at that time (in which case I may just replace the drives to avoid
this problem) or whether it was some other communications glitch (in
which case I may suspect the power supply, try a newer kernel, etc).
With the information at hand, I'm not sure how to fix this, and since
it often is a month or more between occurrences, trial and error is
not likely to help.

> I sure would like to see a timeout in ms [md?] in
> the /sys for the device and a flag for the array to not kick a drive
> for timeout until some number of consecutive timeouts have
> occurred. 

That could be useful.  And, as Neil said, if the SATA driver could be
told to use longer timeouts, that might help.  Neil, if you think that's
a good idea, maybe you could put the request in with the SATA folks?

> I would hope that a drive with multiple partitions would get the
> partitions kicked, not the whole drive at once. So one slow sector
> wouldn't take out multiple arrays.

Only the partition gets kicked out.  Yesterday, this saved me, since I
had timeouts on two drives in RAID5, but all the arrays stayed up because
the partitions didn't happen to be in the same array.

Dan