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Re: raidframe performance question

On Fri, 6 May 2011, Thor Lancelot Simon wrote:

On Thu, May 05, 2011 at 11:08:26PM -0600, Michael L. Hitch wrote:
On Thu, 5 May 2011, Paul Goyette wrote:

The next step was to initialize the raidset parity, so I used raidctl -i

That was almost 10 hours ago, and so far it has done only 26% of
the job!  It appears that the writes are taking ~forever to
complete! systat(1) shows that wd5 (I'm assuming that's the
"parity" drive being written) has twice the transfer-ops and twice
the bytes-transferred, but the drive is 100% busy!

  I wouldn't consider it normal.  I would suspect that the write
cache on the drive is off, and writes are very slow.  You could
check that with dkctl, and enable the write cache for the parity
initialization if the write cache is off.

I have seen this problem with parity rebuilds and RAIDframe on an
intermittent basis for years.  It seems to afflict some machines all
the time, others never.

I wonder if this has something to do with the missed wakeups Matt
reported elsewhere -- the I/Os complete, but the buffer's callback never
gets hit until the next clock tick, so at every clock tick the disk looks


But in this case the drives are mounted in a hot-swap dock, and each slot has its own "Busy" LED indicator. wd4's indicator appears to blink On and Off, while wd5's indicator appears to be solid On. This is what prompted me to look at the smartd stats - thinking that maybe something was wrong with the drive.

Well, anyway, after 21 1/2 hours, it is up to 47% complete. Slow but steady progress.

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