Mirroring Drives

[David Crowe]

How does someone mirror drives under HP-UX11? We have 2 18GB drives that we want to mirror. I thought that you were to use SAM to accomplish this but I have been told that you need a utlity?

Also, the default setup does not utilize the entire 18GB. How do I go about adding another volume to use the remainder of the drive?

[Alexander M. Ermes · Accepted solution]

Hi there.
I think, you need the Mirror software to do what you want. To setup the disk, you should look at the Logical Volume Manager.
Usually, if you buy a machine from HP, all this will be done by HP.
Rgds
Alexander M. Ermes

[Thierry Poels_1]

Hi David,

I you want to mirror your logical volumes you need Mirror-UX software (separate licence, not included in HP-UX).

If you have Mirror-UX software available you have to add the second disk to the same volume group (vgextend or with sam); and then mirror each logical volume (lvextend or sam again).

If it's your boot disk you want to mirror, you might want to make the second disk bootable also (look at pvcreate -B and mkboot, details in some forum threads available) before putting ANYTHING on it.


To use the entire 18GB you could increase the size of current logical volumes or add new logical volumes (in case the maximum phyisical extent of the volume group has not been reached). But it's always handy to have some (or lots ;) of space free for future expansion.

good luck,
Thierry

[James R. Ferguson]

Hi David:

There are no differences in mirroring under 11.x than 10.x.

As I recall (and maybe that's changed), SAM doesn't/didn't handle setting up boot disk mirrors. I always do that at commandline.

The problem in physical drive space utilization you hint at is usually one involving the 'max-pe' parameter as established with 'vgcreate'. The default value is either what you choose, OR the value of the disk used to create the volume group. The problem is that once set, it cannot be changed. Thus, starting with a small disk and trying later to 'vgextend' in larger ones leads to the inability to use all of the space on the larger one.

See the man pages for 'vgcreate' for more information on this.

A good cookbook guide to setting up mirrored disks, including boot disks, can be found in the System Administration Tasks manual:

http://docs.hp.com/hpux/onlinedocs/B2355-90672/B2355-90672.html

Hopefully this helps.

...JRF...

[melvyn burnard]

You need the Mirror/UX product to mirror logical volumes, note that this is what you mirror, NOT discs.