topic Re: Disk Mirroring Issue in Operating System - HP-UX

Disk Mirroring Issue

Vassilios — Wed, 05 Oct 2005 05:49:36 GMT

Hello all.

I'm trying to configure a HP N4000 node or server (in a cluster) to use disk mirroring.

I've done a lvdisplay -v /dev/vg00 and its returned two hardware devices:

a) /dev/dsk/c1t6d0, and
b) /dev/dsk/c2t6d0

doing an lvdisplay -v on all logical volumes (found from a bdf), we see that all lvol's belong to c1t6d0.

Therefore, can I assume that c2t6d0 is in fact the spare the disk? It tells me it has 2170 of 2170 Free space.

However, my concern is as follows:

Because this node is in a cluster, when I do a checkconf, we get this warning:

Warning: The disk at /dev/dsk/c0t1d0 on node does not have an ID.

So, what does this mean? why didnt c0t1d0 appear in the pvdisplay or vgdisplay or even lvdisplay commands??

Thanks for any assistance

Re: Disk Mirroring Issue

RAC_1 — Wed, 05 Oct 2005 05:54:30 GMT

man cmcheckconf. By default cmcheck will check all diks on all nodes in cluster.

Check option -k, this will limit the disk checking to disks identified in config file.

Re: Disk Mirroring Issue

melvyn burnard — Wed, 05 Oct 2005 05:56:50 GMT

well what is the disk at /dev/dsk/c0t1d0?
A CDROM or DVDROM?

All that cmcheckconf is telling you is that the disk at that address has not had pvcreate performed upon it, so it cannot be used in the cluster.
This also means it is not part of a VG.
As it says, just a warning

Re: Disk Mirroring Issue

Vassilios — Wed, 05 Oct 2005 05:59:46 GMT

OK Thanks all. SO can i assume then that c2t6d0 is in fact the correct hardware device that can be used as a disk-mirror for c1t6d0 ??

Thanks for your confirmation.

Re: Disk Mirroring Issue

Nick Wickens — Wed, 05 Oct 2005 06:01:46 GMT

As to why it did'nt appear in your commands - Simply means its not allocated to that volume group or indeed perhaps any volume group and is a free disk.

Start with ioscan -fnCdisk to locate disks on your system before moving on to pvdisplay commands.

Re: Disk Mirroring Issue

melvyn burnard — Wed, 05 Oct 2005 06:04:36 GMT

If vgdisplay shows this disk as part of the VG, and the lvdisplays show that none of the current LV's are using this disk, then yes it can be used for mirroring.

Re: Disk Mirroring Issue

Stuart Abramson — Wed, 05 Oct 2005 08:05:03 GMT

Here's a little script to mirror your vg00. You didn't ask for it, but I thought it might be useful to you. No charge.

##
# mirror_root_disk.ksh SDA 10/23/03
#
# Starting conditions:
# cLEFT is already built correctly.
# cRIGHT is "empty" and unassigned.
#

# Define disks

cLEFT=c0t6d0 # 1/0/0/3/0.6.0
cRIGHT=c4t6d0 # 1/0/1/0/0/1/1.6.0

# Make right disk bootable

pvcreate -B /dev/rdsk/${cRIGHT}
vgextend vg00 /dev/dsk/${cRIGHT}
mkboot -l /dev/rdsk/${cRIGHT} # boot disk only
mkboot -a "hpux -lq (;0)/stand/vmunix" /dev/rdsk/${cRIGHT}

# Mirror the LVs

vgdisplay -v vg00 | grep "LV Name" | awk '{print $3}' | while read LV
do
lvextend -m 1 $LV /dev/dsk/${cRIGHT}
#lvdisplay $LV
done

#

lvlnboot -R # Update BDRAs
lvlnboot -v # Shows boot status

# Verify..

lifcp /dev/dsk/${cLEFT}:AUTO -
lifcp /dev/dsk/${cRIGHT}:AUTO -
lifls /dev/dsk/${cLEFT}
lifls /dev/rdsk/${cRIGHT}

setboot