From: Jim Gray (grayj@erinet.com)
Date: Sat Aug 16 2003 - 18:40:22 EDT
Thanks to the over twenty (2) respondents who provided helpful advice.
We completed the replacement of the primary disk in the vg00 volume
group several hours ago, with only 45 minutes of downtime. While all
of the respondents shared the same advise, I'll post Galen Scalone's as
the most thorough, since he referenced an article he wrote about
MirrorDisk/UX.
Excerpt from article:
Recovery of a Failed Disk in vg00
As system admins, we should expect disks to fail every now and then.
The idea behind using MirrorDisk/UX is that if you do have a disk
failure or SCSI card failure, the system still has one copy of data
that it needs to operate and will continue to run. It still has one set
of extents it can read from and write to, and it does not matter which
set it has--the original or the mirror copy.
There are a few ways to find out whether a disk has failed, although
vgdisplay -v is probably the quickest. When vgdisplay -v /dev/vg00 is
run, it will show the logical volumes in the vg00 volume group and the
disks in the vg00 volume group. When one of the disks in the volume
group has failed, vgdisplay will show the disk as unavailable, and will
also show some or all of the logical volumes as being in a stale state.
Once you determine which disk has failed, you will need to replace it.
Since these examples are using hot swappable HP disks, replacement
should be pretty simple--just remove the bad disk and insert a new
disk. Let's say c0t0d0 and c1t0d0 are in the /dev/vg00 volume group,
and say that c0t0d0 has failed. Remove the disk from the cabinet, and
replace with the same size disk. Next is the software portion. Once the
new disk is in place:
Boot the system. You will need to select "boot alternate" if the
primary disk failed, otherwise the system will boot normally with some
error messages regarding the failed disk.
vgcfgrestore n /dev/vg00 /dev/rdsk/c0t0d0 This command restores LVM
configuration to the reserved header area on the new disk from the
file /etc/lvmconf/vg00.conf, the volume group configuration backup file.
vgchange -a y /dev/vg00 This command tries to activate any physical
volumes in the volume group that had previously been unavailable, or
missing.
vgsync /dev/vg00 This command will re-sync the physical extents of all
logical volumes in the volume group.
Alternatively:
lvsync /dev/vg00/lvol1 This command will re-sync one logical volume at
a time; repeat for all volumes.
At this point your mirror copies are valid again. Notice that in the
previous example, the original disk is the disk that failed, not the
mirror. If for some reason you cannot immediately replace the disk, you
will need to make sure the machine, at boot time, knows which disk to
boot from, in this case the mirror. We would setboot p 16/0.0 to set
the primary boot path to point to the mirror disk.
Here is a link to the full article:
http://www.interex.org/pubcontent/enterprise/sep00/13scalone.html
> We have a two disk root volume group, mirrored using Mirrordisk/UX,
> running HP-UX 10.20. One of the disks has failed and we have
> scheduled a replacement for Saturday afternoon. We cannot run any
> vgxxx commands, since they hang the session.
>
> 1) How can we determine if the primary or alternate disk has failed.
>
> 2) Any quick and dirty steps to remove and replace the faulty disk.
>
> We haven't had any HP disk issues in a while, so these skills are a
> little rusty. TIA. Will summarize.
>
>
> Jim Gray
> grayj@erinet.com
> Cellular (937)-470-8188
>
>
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Jim Gray
grayj@erinet.com
Cellular (937)-470-8188
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