topic Re: Mirroring Root Disk with different drives in Operating System - HP-UX

Mirroring Root Disk with different drives

John Downs_1 — Thu, 24 Oct 2002 14:35:43 GMT

Greetings!

I have a c240 running HP-UX 11.00 with Mirroring. I'd like to mirror the root disk with an available internal disk. My root disk is a 4g drive and the available disk is a 9gig drive. I looked high and low for information on this but couldn't find any.

Your advice will be greatly appreciated.

-john

Re: Mirroring Root Disk with different drives

S.K. Chan — Thu, 24 Oct 2002 14:43:42 GMT

This is the process I used all the time.

o Assuming c1t2d0 is primary disk and c2t2d0 is the disk to be mirrored.
o Assuming (lvol1=/stand;lvol2=primary swap;lvol3=/;lvol4->lvol8=the rest)

# swlist -l bundle| grep -i mirror
=> Make sure you have MirrorUX installed
# pvcreate -f -B /dev/rdsk/c2t2d0
# mkboot -l /dev/rdsk/c2t2d0
=> Create boot track (place boot utilities in boot area), -l means treat device as LVM disk.
# mkboot -a "hpux -lq" /dev/rdsk/c2t2d0
=> Add AUTO file in boot LIF area, "lq" option is to bypass quorum check.
=> Repeat for primary disk (c1t2d0) as well.
# lifcp /dev/rdsk/c2t2d0:AUTO -
=> Check content of AUTO file. Repeat for primary disk (c1t2d0).
# vgextend /dev/vg00 /dev/dsk/c2t2d0
=> Adding disk to root VG.
# pvdisplay -v /dev/dsk/c2t2d0
=> Note of the order of LVs (assuming it's lvol1,lvol2,lvol3,lvol4->lvol8)
# lvextend -m 1 /dev/vg00/lvol1 /dev/dsk/c2t2d0
=> Repeat for lvol2->lvol8
# lvlnboot -r /dev/vg00/lvol3 /dev/vg00
# lvlnboot -b /dev/vg00/lvol1 /dev/vg00
# lvlnboot -s /dev/vg00/lvol2 /dev/vg00
# lvlnboot -d /dev/vg00/lvol2 /dev/vg00
=> Update BDRA (root, boot, swap and dump)
# lvlnboot -v
=> Check to make sure both disks are listed for root, boot and swap definition.
# setboot
=> Display boot path.
# setboot -a 0/0/2/0.2.0
=> Change alternate boot path to mirrored disk.
# shutdown -r -y 0
=> Interrupt upon bootup and select alt path to boot from in order to test.

For the official doc take a look at the SOftware Recovery Handbook (chap 16)
http://us-support3.external.hp.com/iv/data/documents/DE_SW_UX_swrec_EN_01_E/Introduction.pdf

Re: Mirroring Root Disk with different drives

Jean-Louis Phelix — Thu, 24 Oct 2002 14:44:43 GMT

Hi,

You can do it, but if your vg has been created with default options for max PE and PE size, you will not be able to use it entirely (some PE will not be addressed). Theses parameters cannot be modified without reinstalling your system (but you can use ignite).

Regards,

Jean-Louis.

Re: Mirroring Root Disk with different drives

S.K. Chan — Thu, 24 Oct 2002 14:45:54 GMT

One more thought .. though this would work just fine (ie using different size mirror disk) but if you can I would recommend the same size root disks. I'm just not used to using differnt size disks plus I do not know if that can affect performance, I doubt it though.

Re: Mirroring Root Disk with different drives

Martin Johnson — Thu, 24 Oct 2002 15:11:35 GMT

I would recommend that you install the latest LVM patches before mirroring.

HTH
Marty

Re: Mirroring Root Disk with different drives

Sandip Ghosh — Thu, 24 Oct 2002 15:39:14 GMT

As mentioned by jean, if you had not created the VG with that 9GB disk probably you would not able to access excess of 4 GB.

In this situation I would recomend you to take an ignite backup of vg00 and restore it on 9GB disk. And then do the mirroring on the 4GB Disk as described by SK.

And regarding the size difference, nothing will happen. Only the limitation is , you can mirror only upto the size of your smaller disk.

Sandip

Re: Mirroring Root Disk with different drives

Bill Hassell — Thu, 24 Oct 2002 17:24:29 GMT

Although mirroring should be performed between like disks, it will work. The downside is the the slowest disk (very likely the 4Gb one) will define the overall write speed for the volume. That is, the faster disk will just be idle which the slower disk finishes.

Re: Mirroring Root Disk with different drives

John Downs_1 — Fri, 25 Oct 2002 14:48:18 GMT

You guys are great! It looks like my only limitation is lossing 5 gig of space on the 9gig drive.

Thanks!

-john

Re: Mirroring Root Disk with different drives

Paula J Frazer-Campbell — Fri, 25 Oct 2002 14:48:19 GMT

John

As Sandip has said reverse the two disks and you will not loose the 5 gig.

Paula

Re: Mirroring Root Disk with different drives

James R. Ferguson — Fri, 25 Oct 2002 14:52:07 GMT

Hi John:

You might consider making an Ignite 'make_tape_recovery' tape of vg00 and reinstalling your system. If you do so, choose the 9GB disk as the installation target, *or*, preferably, modify the target volume group parameters to specify a 'max_pe' and 'pe_size' value that spans at *least* a 9GB volume. Then, remirror your volume group.

You can't change the 'max_pe' and 'pe_size' once a volume group is created.

The suggestion above would allow you to replace the 4GB disk with a larger one later and be able to expand utilization of the physical disk beyond 4GB.

Regards!

...JRF...

Re: Mirroring Root Disk with different drives

fg_1 — Fri, 25 Oct 2002 15:20:15 GMT

Just to very much agree with what Jim F. said.

You may want to run your ignite tape and rebuild your root volume group on the 9GB disk making that the primary drive then mirror over to the 4GB disk. You won't loose the 5GB even though the diskspace is allocated to VG00 it is still usable by you for other things.

have a good day.

fg

Re: Mirroring Root Disk with different drives

John Downs_1 — Fri, 25 Oct 2002 16:15:12 GMT

I've never used ignite. Does it come with the standard install of HP-UX? Will it allow me to recreate the same boot image/filesystems/patches that I currently have on the 4 gig drive?

-john

Re: Mirroring Root Disk with different drives

James R. Ferguson — Fri, 25 Oct 2002 16:35:06 GMT

Hi (again) John:

A current version of Ignite along with documentation can be obtained from the Ignite site here:

http://www.software.hp.com/products/IUX/index.html

Installation is done with 'swinstall' and includes man pages. A reboot is not necessary to configure Ignite.

You should always have a current Ignite recovery tape available. With it, you can capture a bootable image of your root volume group (vg00) and use it to clone or restore a server. You can also use it to recreate your root volume group logical volume sizes by doing the equivalent of a "cold" install.

Yes, your *complete* system configuration is captured by an Ignite recovery tape.

Use this to create a tape archive for all of vg00:

# make_tape_recovery -x inc_entire=vg00 -I -v -a /dev/rmt/0mn

The 'make_tape_recovery' command also allows the specification of include or exclude options for other volume groups, and directories (see the man pages), although Ignite is *not* designed to be a backup solution.

For cloning, or for installing, interrupt the boot process and boot from the Ignite tape. You can choose the Advanced Installation tab and resize any filesystems as needed.

I have found that it is easiest to defer network configuration during the Ignite recovery. Indicate when queried by Ignite that you wish to run '/sbin/set_parms' to configure networking afterwards.

Regards!

...JRF...