Hello, all.
This is probably a very common question, but I didn't see a clear answer
while looking at the list archives, so I'm going to ask for your
assistance.
We've got a raid 5 with three drives. I'll spare you the comedy of errors
and/or sob story that you've all probably heard before, but the upshot is
that we have two failed drives and no current backup.
When the second drive failed, the raid went offline right away. The
second failure was apparently due to a write fail on the disk. I presume
that the data on the second failed drive and the main drive is mostly in
synch, except for the last change made. My conclusion is that other than
the file being written, the rest of the data should be okay. Please tell
me if I'm wrong there.
We got identical drives to the one good drive and the second failure, and
have used dd to copy the data on to those volumes, so we can attempt to
recover and not hurt our only copies of this data. I've seen another
message on this list which suggests this should work. Copies were made
with no errors.
At the moment, my system is a little old and does not have mdadm on it.
Is it worth getting and installing this, or am I best to stick with the
original raidtools?
The question of the hour is: How do I get the two drives to come back
on-line in degraded mode? They have different event counters and will not
come up.
Any advice or direction you can provide will be very much appreciated.
--
Louis Erickson - wwonko@rdwarf.com - http://www.rdwarf.com/~wwonko/
No matter what other nations may say about the United States,
immigration is still the sincerest form of flattery.
I didn't see any other answers, so I'll take a shot...
On Mon, Feb 02, 2004 at 03:44:57PM -0800, Louis Erickson wrote:
[snip]
We've got a raid 5 with three drives. I'll spare you the comedy of errors
and/or sob story that you've all probably heard before, but the upshot is
that we have two failed drives and no current backup.
When the second drive failed, the raid went offline right away. The
second failure was apparently due to a write fail on the disk. I presume
that the data on the second failed drive and the main drive is mostly in
synch, except for the last change made. My conclusion is that other than
the file being written, the rest of the data should be okay. Please tell
me if I'm wrong there.
That's a reasonable guess, I think. It depends to some extent what
went bad... once I had a drive that developed a few bad sectors, but
the bad sectors were in the middle of the inodes for my /home
partition, so it did some pretty serious damage.
We got identical drives to the one good drive and the second
failure, and have used dd to copy the data on to those volumes, so
we can attempt to recover and not hurt our only copies of this data.
I've seen another message on this list which suggests this should
work. Copies were made with no errors.
At the moment, my system is a little old and does not have mdadm on it.
Is it worth getting and installing this, or am I best to stick with the
original raidtools?
I advise you to get and install mdadm -- it has worked fine for me and
mdadm seems to be the overwhelming preference of the posters to this
list and thus easier to get support for.
The question of the hour is: How do I get the two drives to come back
on-line in degraded mode? They have different event counters and will not
come up.
Any advice or direction you can provide will be very much appreciated.
Once you have mdadm,
mdadm --assemble /dev/md<whatever> --force <good drive #1> <good drive
#2> missing
should work for you. Note that "missing" is a literal string which
you supply instead of a third device name, indicating that you want to
assemble a three-drive array in degraded mode without one of its
drives. You should see some message in the logs about forcing the
event count of some drive or another. "--force" is necessary because
the remaining drives' event counts are different.
-Steve
On Tue, 3 Feb 2004, Steven Ihde wrote:
I didn't see any other answers, so I'll take a shot...
I did get one other private answer, from Andreas Arens.
I thought I'd take a moment and thank both of you for your assitance with
this. The suggestions were correct and were exactly what I needed to get
the RAID5 back on-line and all the data was intact.
Thank you VERY much. I suspect I'd have figured it out eventually, but
not only did this make it much simpler, it reassured me that I'm not the
only one fool enough to have such a problem.
I advise you to get and install mdadm -- it has worked fine for me and
mdadm seems to be the overwhelming preference of the posters to this
list and thus easier to get support for.
I did install mdadm, and it did the trick. It seems to be much simpler.
I'll also be able to retire my Perl script in favor of monitor mode.
Thanks again!
--
Louis Erickson - wwonko@rdwarf.com - http://www.rdwarf.com/~wwonko/
In Pocataligo, Georgia, it is a violation for a woman over 200 pounds
and attired in shorts to pilot or ride in an airplane.