Mirroring

[Gunther Schulze]

I've got a DS2100 JBOD attached to a rp5430 running 11.0. The DS2100 holds 4 18GB drives. I have assigned two of these drives to a database as one logical drive. How would I mirror this logical drive composed of two physical drives to the remaining two drives?

[Stefan Farrelly]

1. Add the remaining 2 drives into the same volume group as your existing ones. (use pvcreate and vgextend)

2. use the lvextend -m 1
command to mirror each lvol you need to. If you want to specifiy exactly which disk to mirror to add the /dev/dsk/cxxxxx device to the lvextend command.

Thats it !

[Jim Turner]

Howdy!

You don't mention whether or not you're running these two DB drives as raw or cooked. Mirroring (Mirror/UX) is done by logical volume (LV). I believe the default policy is strict allocation which will ensure that mirrored extents go to a physical drive other than where the original is located.

You will need the purchased Mirror/UX product. I can post/attach the procedure I use to mirror LV's in vg00 (for alternate boot) if desired. It could be easily adapted to non-vg00 use.

Cheers,
Jim

[Duncan Edmonstone]

You do, of course need to have the software MirrorDisk/UX installed to do this. Check if you have this s/w using:

swlist


HTH

Duncan

[Gunther Schulze]

Yes, I do have the MirroDisk/UX product. I would appreciate the procedure you use. I was just curious if the mirroring procedure would be a little trick since I'm mirroring two physical disks as one logical drive to another two physical disks that haven't been configured as a logical drive.

[Jim Turner · Accepted solution]

Modify as necessary . . .

Mirror Boot Drive

For this example, the original boot disk is /dev/dsk/c0t6d0 (8/4.6.0), and the new mirror disk is /dev/dsk/c0t5d0 (8/4.5.0). You will need to substitute the disk devices and hardware paths from the new server as appropriate. Having LV names of lvol1 up through a max of lvol9 is also assumed.

# Prepare bootable disk.
pvcreate -B -f /dev/rdsk/c0t5d0

# Add the new disk to /dev/vg00.
vgextend /dev/vg00 /dev/dsk/c0t5d0

# Write boot (LIF) info to the disk.
mkboot /dev/rdsk/c0t5d0

# Update AUTO file on both disks so vg00 will activate without a quorum.
mkboot -a "hpux -lq" /dev/rdsk/c0t5d0
mkboot -a "hpux -lq" /dev/rdsk/c0t6d0

Mirror each logical volume in vg00. Note "ls -1" means "ls minus one":
# for i in $(ls -1 /dev/vg00/lvol*)
> do
> lvextend -m 1 $i
> done
The newly allocated mirrors are now being synchronized. This operation will take some time. Please wait ....
[Note that this proc assumes all LV's in vg00 are named lvol1, lvol2, etc. If not, you must mirror lvol1, lvol2, and lvol3 in that order before any others.]

Disable mirror write cache and mirror consistency recovery for
swap/dump. Assuming swap/dump is lvol2:
# lvchange -M n -c n /dev/vg00/lvol2

# Recover any missing links to LV???s and update the BDRA of each bootable PV.
lvlnboot ???R

# Set BOOT, SWAP, and ROOT.
lvlnboot -b /dev/vg00/lvol1
lvlnboot -s /dev/vg00/lvol2
lvlnboot -r /dev/vg00/lvol3

# Check stable storage.
setboot

# If boot paths and switches are not set properly,
# perform the following as needed.
setboot -p 8/4.6.0 # Primary boot path
setboot -a 8/4.5.0 # Alternate boot path
setboot -s on -b on # Activate autosearch and autoboot

During a "normal" reboot, the primary boot disk will be used. If the system boots and the primary boot disk has failed, the system will automatically boot off of the alternate boot disk.

[Gunther Schulze]

Thanks very much !