[NBLUG/talk] RAID-5 array resync causes severe audio glitches

[Lincoln Peters]

Early on Thursday morning, I found that my RAID-5 array was running 
like crazy, causing severe delays for everything that required I/O on the 
filesystem.  So I ran "mdadm --detail /dev/md1", and found the following 
lines of particular interest:

/dev/md1:
[snip]
    Update Time : Thu Oct  5 04:51:36 2006
          State : active, resyncing
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0
[snip]

 Rebuild Status : 92% complete


Normally, a brief period of sluggish I/O due to this kind of stuff wouldn't be 
a major issue, but this is the computer that I use as my alarm clock (I 
described my "alarm clock" shell script in an e-mail to this list back in 
January).  It plays music files through Amarok, and if it can't pull the data 
fast enough (as was the case here), it skips almost every second and sounds 
REALLY bad.  It's not a very nice way to wake up in the morning!

Any ideas what might have led to it having to do a resync on a RAID array that 
wasn't degraded?  Or how to change the behavior of a resync so that it has 
less of a performance hit?


-- 
Lincoln Peters		<sampln at sbcglobal.net>

If you don't say anything, you won't be called on to repeat it.
		-- Calvin Coolidge