On Tue, May 4, 2010 at 10:26 AM, John Hornbuckle
<[email protected]> wrote:
> So, what gives? The array reports everything is fine. But obviously,
> something is funky. I can restore the four corrupt files from a
> backup—that’s no problem. But not if I can’t first delete the bad versions.

  I'd call Dell tech support.  It's free and sometimes even helpful.

  Not knowing more, my guess would be that one of the other disks has
some bad blocks.

  Scenario: Most filesystems have a lot of files which are never or
rarely read.  Plus RAID 5 provides redundancy -- the controller may
normally read the "primary" set of on-disk blocks and ignore the
redundant blocks.  End result, you've got blocks allocated on disk,
but which are never read.  Then a disk fails.  Now the controller has
to read *every* block of *all* the other disks, in order to rebuild
the failed member.  Boom.  That's when you discoverer that one of the
other disks has had bad blocks for years.

  Unfortunately, the only way to recovery from this scenario is to
restore from good backups.

  For this reason, good controllers have a "patrol read" feature (or
"background scrub", etc.), where they regularly read all blocks from
all disks, to discover bad blocks as soon as they happen.

-- Ben

~ Finally, powerful endpoint security that ISN'T a resource hog! ~
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