Re: Mdadm -- Restoring an array

Short summary:

It turns out that I must have formatted three of the drives, which is
why I only got one listed when I scanned them.  It turns out the one
command line:

mdadm --assemble /dev/md0 /dev/hde1 /dev/hdf1 /dev/hdg1 /dev/hdh1

did it perfectly.  I had been doing it without the "1" on the end to
specify a partition.

It's all working just fine now.

Hal

On Tuesday 17 October 2006 03:07, Hal Vaughan wrote:
I have a server with one drive that has the boot and system on it and
a RAID5 device managed by mdadm. The RAID is made up of 3 hard
drives with a 4th spare also hooked up.

The system drive crashed and I restored it. The problem is in the
past, when I've tried to restore a RAID, I've had trouble with it.
The man page for mdadm makes it look like a RAID can be reassembled
with just a --assemble option given on the command line, but it keeps
asking for more information. I thought there was a scan mode, to
tell mdadm to scan local drives and re-assemble an existing RAID.
I've tried different options previously to restore a mdadm RAID, but
had trouble.

There is no data on this drive that can't be reconstructed, but to do
so would be a bit of a pain and take time (and the backup system for
this RAID was still experimental).

Does anyone have experience rebuilding a mdadm RAID when the config
info has been wiped out? (I wouldn't think that would matter, since
the mdadm config files that should have held the RAID info always
seemed to be empty on my systems.)

Thanks for any help on this. It would be a lot easier to restore it
with a single command than to rebuild the data.

Hal

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