Mirroring HP-UX system drive?

[Larry Finnegan]

I have an HP-UX system with two internal drives. One of the drives is set up as a PV in vg00 and then all the OS filesystems exist in different LVs. Pretty standard. I want to mirror this drive to the second internal drive but can't seem to find a way to do it. We don't have licensing for MirrorDisk UX and I can't mirror with lvextend -m. Our vendor mentioned something a while back about using Veritas to do the mirroring which we apparently do have a license for since I'm using VxFS for my LVs. Poking around the man pages I found a command 'vxdiskadm'. I tried adding the disk devices (c2t0d0 and c3t2d0) to the vx group but get a message about these disks not being found. Any ideas? Any more info I should be posting beyond this? This is an HP-UX 11.11 system that I'm talking about:

HP-UX server1 B.11.11 U 9000/800 1636854775 unlimited-user license

[Sundar_7]

vg00 is LVM and you cannot mirror using the VxVM. The VXFS filesystem comes with the OS but you get only the base veritas volume manager with HP-UX 11i. These are two different products.

[Geoff Wild]

You can't use VxVm on 11.11 for the system disk - you need to purchase MirrorDisk UX.

Rgds...Geoff

[Chan 007]

Larry,

root disks can't be used by Veritas. You must have MirrorUX to do mirroring.

Instead of buying Veritas you can buy MirrorUX Lisence...

If you have purchased UX Ent Edition, you will get all free.

Chan

[Sivakumar TS]

Hi,

In HPUX 11.11 only wat to mirror the root disk is to install MirrorUX and do a LVM mirror.

In HPUX 11.23 onwards root mirroring thrc VxVM is also possible.

In 11.23 you can aslo convert a LVM root disk to a VxVM root disk.

With Regards,

Siva.

[Mridul Shrivastava]

Another thing i want to clear that Vxfs has nothing to do with VxVM as it is a filesystem. These disks are managed by LVM only so whatever Shiva has suggested I agree with that.

[Indrajit_1]

Hi;

You need to purchase License for MirrorUX. Then u go can go ahead with following commands.

#diskinfo /dev/rdsk/c3t2d0

#pvcreate /dev/rdsk/c3t2d0
#vgextend /dev/vg_name /dev/dsk/c3t2d0
#vgdisplay -v /dev/vg_name

Please note down all the logical volume name

#lvdisplay -v /dev/vg_name/fs_lvol1
#lvextend -m 1 /dev/vg_name/fs_lvol1 /dev/dsk/c3t2d0

Cheers
indrajit

[Victor Fridyev]

Hi,

If you want to mirror system drive, you need HPUX Mirror license, but if a backup copy of you system drive is enough for you, you can copy the sytem disk onto the second one as following:

dd if=/dev/rdsk/XXXX of=/dev/rdsk/YYYY bs=32768k

If to do this when the computer is not too active and there is not a database on it, the backup is good. If the system disk failed, you replace it by the copy and boot from it.
I use this approache for years and it works. Additional advantage of such a backup is a possibility of fast undo after wrong upgrade.

HTH

[Steven E. Protter]

11.11 can be convereted to vxvm.

Even on 11i vxvm can mirror rootvg.

Otherwise its pay for mirror/ux or use dd. I've seen the dd thing work a few things. Its pretty amazing, but you do need to boot your system to bring the copy online,.

:-)

SEP

[David Nixon]

VxVM rootability is available for 11.11
and can be selected during a cold install
- Mirroring can be left until later.

If you can get the downtime I would suggest installing a VxVM root
dg on your second drive: once
this set-up had been tested you could
initiate mirroring to the first drive;
using the 'vxrootmir' command.

N.b. despite what some documentation
implies, the bundled product allows all volumes in a root dg to be mirrored.



David

[TwoProc]

Well If you can't buy Mirror, then I agree with Viktor, go ahead and use "dd" make a copy of the root disk.

Make sure that the two disks are EXACTLY the same (especially, make sure that even though HP SAYS that they are the same, the "dd target" disk has the same number or slightly more number of segments. There are HP disks out there with the same HP part number (AXXXX) which have slightly less disk space than their original. I'll agree it's rare, but I have seen it myself. When it happened to me, the "lost space" was only in swap, so it was not a huge loss. Just an FYI. If they don't have the same number of segments, then the one your copying to should be the same disk, but have MORE segments than the source root disk.

If you're using the "dd" method and have had a root disk failure you've got a few options that I can quickly think of:

A) Shutdown (if not already down :-) ). Unplug the bad root disk, and move the disk that you've been "dd" to in it's place. Reboot, you should be up and running fine (especially you've been running the "dd" everyday). When you get your new disk in, put it where the "cold spare" disk goes and run the dd to it so that you have a new backup.

B) Use another computer that is up to dd copy from the backup disk to the new disk that replaces the broken one. Then put both back in the cabinet of down server in their original locations and reboot. You should be back up. Note that using this method, you can use a "dd tape" instead of a disk target for the backup with the same result. I find that old HP servers/workstations that have lived past their prime are great for this task, just try to keep some of the various types of scsi interface cards necessary to get it done installed on the old box if you can.

The advantage of the disk solution over tape is that you can quickly reboot the server with the failed root drive, with tape you've got to go to use another box to recreate your root disk.

That being said, I think you should buy mirror disk - and do both. Mirror your drives, and do regular "dd copies" to tape. You should also get familiar with using ignite backups. That way, you've got three ways out of a failure, and with MirrorDiskUX, you will be able recover from the failure with NO DOWNTIME.

[Vivek Pendse]

Hi,

You will need to have Mirror/UX License for B.11.11 version. Then only you can do the mirroring of root disk.

Regards,
Vivek Pendse