Disaster Recovery by using split mirrored root disk

[Eileen Millen]

This is a proposed DR plan.
I can see some possible problems with it.
We have not tested the mirroring parts at all.
The plan is to split the mirrored root disk.
Install the basic OS onto one of the disks.
Install networker backup/recover software.
restore /, /stand, /var, /usr, /opt, /tmp
from backup tape. Do a second restore to recreate all the links. This does work.

After this is successful, the plan is to boot from the other original root disk and then resync to the newer DR disk.
Do we have to pvcreate -f the disk that the recovery was done onto so that it can be resynced? Is is possible to sync older data over a newer install?

We do have Ignite, but don't have space for network root disk archives.
We do not have spare disks for the A class system. My choice would be to do the DR testing on new disks.

Thanks for any input.
Eileen

[Tim D Fulford]

Well it will probably work, but why not just use IgniteUX to tape in addition to your level 0 filesystem backups., no need to do things like resyncing disks etc...

Word of warning **- I did a DR (for real) with new install & install files from tape backup to get thigs as they were, it takes loads of time to do it this way. Stricktly speaking OS, Apps, diags, patches, then lvl 0 tape... all this needs to be done and can take quite some time. At the end of the day it is a DISASTER & you want service up ASAP. This should be justofication for atleast Ignite --> tape if not ignite to server...

you will need to do pvcreate -f as the disk will have an LVM headder info in it. if it is a boot disk pvcreate -fB. If you are mounting it up to copy data back you may need to do
vgchange -a y -q n vgold00 to get the old OS back on-line

Good luck

Tim

[Tim D Fulford]

Eileen

Sorry.... I think I ran a few things together here. mount old OS back up
mkdir /dev/vgold00
mknod /dev/vgold00/group
vgimport vgold00 /dev/dsk/c?t?d0
vgchange -a y -q n vgold00
mount /dev/vgold00/lvol3 /oldroot

Copy back data (saves doing tape restore)

re-mirror
umount /dev/vgold00/...
vgexport vgold00
pvcreate -fB /dev/rdsk/c?t?d0
vgextend vg00 /dev/dsk/c?t?d0
lvextend -m 1 /dev/vg00/lvol1
lvextend -m 1 ....

Tim

[Eileen Millen]

We will have an Ignite tape, but the company DR procedure is to use the above method.
Some people here do not trust DAT tapes.
make_tape_recovery is the second choice
I will be setting up an adminstrative system that will have lots of disk space, but I don't have the resources yet.

Eileen

[James R. Ferguson]

Hi Eileen:

You need to look at Ignite. With Ignite's 'make_tape_recovery' you have a vg00 "image" that represents your OS as you patched it. You can take this to a disaster recovery site, load it, and in about an hour be restoring your non-vg00 data. Disaster recovery is far, far more than replicating or restoring a boot disk, but Ignite offers a grand starting point from which a full plan can be built.

Regards!

...JRF...

[A. Clay Stephenson]

Hi Eileen:

I wholly agree that your best option is to use IgniteUX. You will be miles ahead and let's face it; a tape will be much easier to store than a disk.

I can tell you a simpler method of your disk mirror stuff and I know this works.
First make sure that you can boot without quorum my adding -lq to your boot string.

e.g.
mkboot -a "hpux -lq (;0)/stand/vmunix" /dev/rdsk/c1t6d0 (or whatever your boot disk or mirror is)

Do this for both disks.


Now, if you have a 3rd identical disk,
dd if=/dev/rdsk/c1t6d0 of=/dev/rdsk/c3t1d0 bs=8000k

This should be done on a rather quietscent system but it will make an image of your boot disk. Because this is done on mounted filesystems, when you move this disk to a new box, it will do an fsck but I have never had a 'lifeboat' to fail yet and it's even faster than Ignite. Simply remove the boot disk and mirror and insert the move the 'lifeboat' to the boot slot. I actually run a cronjob to do this early Sunday mornings on all my boxes or before a major patch install.

This protects me from two things that Mirror/UX does not: 1) Really, really bad patches 2) My own stupidity.

Regards, Clay

[Martin Johnson]

Ignite is definately the way to go. It cuts hours off the recovery time. Just be aware that Ignite does not recover mirrored disks. You will have to do that manually after the Ingite recovery.


HTH
Marty