Re: Software RAID crash > /dev/md0: Invalid argument

On Thursday September 16, gordon@drogon.net wrote:

On Thu, 16 Sep 2004, Luca Berra wrote:

quoted

On Thu, Sep 16, 2004 at 07:30:49AM -0400, Scott Bolander wrote:

quoted

I have a Mandrake 10 server with a 40gb boot drive and a three 200gb disk
software raid 5 array using reiserfs.  A disk went bad; so i have replaced
it.

Doing the normal things to get it back up don't work:

[root@server root]#raidhotadd /dev/md0 /dev/hdg

....

quoted

# cat /etc/raidtab
raiddev       /dev/md0
raid-level    5
chunk-size    128k
persistent-superblock 1
nr-raid-disks 3
   device    /dev/hdg1
   raid-disk 0
   device    /dev/hdi1
   raid-disk 1
   device    /dev/hdk1
   raid-disk 2

so you replaced the first disk in the array?
raidtools are not capable of handling this.
switch to mdadm

Er - Maybe I'm missing something (like the original message in this
thread), but I've successfully used raidtools to raidhotremove and
raidhotadd the first drive (and others) in a raid5 set.., Once on a real
'hot' system, a server with SCSI drives which I didn't power cycle, and on
IDE systems where I've done a sequence of raidhotremove, power down,
change physical drive, boot up, cfdisk new drive, then raidhotadd...

The problem is with "raidstart", not "raidhotremove".
If you use auto-detect then you won't have a problem.
If you use raidstart to start your arrays, you could have a problem.

NeilBrown