[manoj.aix]

Hi,

I want to know how I can create mirroring in Aix what are steps?

and after mirroring how can i come to know on which hard disk Operating System is installed actually,for example if 2 hard disk is there hdisk0,hdisk1?

[drax]

Mirroring in AIX is pretty straightforward if you understand the logical volume management it has built in.

If you "lsvg -l rootvg" you will see each logical volume in the volume group. These mostly coincide with filesystems, but are sometimes used as raw areas of storage (eg hd5 the boot lv). Note the LP and PP columns.

Each logical volume is made up of a number of logical partitions (LPs).

Each logical partition is matched with a single physical partition (1 LP = 1 PP).

When a logical volume is mirrored one more PP is related to a single LP (1 LP = 2 PP).

So mirroring is done by increasing the number of PP's related to the LP's making up a logical volume.

Command used to make copies (aka mirror a logical volume):
mklvcopy

Of course smit can help out here, although I prefer a more controlled manual approach.
smitty mirrorvg

If you are planning on mirroring rootvg there are several gotcha's to keep in mind.
- Consider two non-mirrored primary and secondary dump areas (sysdumpdev) on separate disks
- Consider mirroring paging hd6 (there are pros/cons here not sure which is best) as it will impact performance, but will improve availability.

A quick google for "mirror rootvg aix" will get you several hits for a procedure to.

[ross.mather]

You can always see which disks are part of the root volume group by doing:

lsvg -p rootvg
and
lsvg -l rootvg to see how the LPs and PPs are distributed. There should be 2 PPs for every LP in a mirrored system.

To create the mirror (in the example on hdisk1)
extendvg rootvg hdisk1
mirrorvg -S -c2 rootvg hdisk1
syncvg -v rootvg

Do the syncvg when the system is quiet. If you can us the -P 32 parameter to make the mirror as quick as possible.

bosboot -a
to rebuild the hd5 boot

bootlist -m hdisk0 hdisk1

As per the mail from drax think about dump devices, and paging space. I don't mirror paging spaces, I create one on each disk and Icreate one dump device on each disk.

[kinay61]

Be careful, if you add a new FS after the mirroring, this new one will not be mirrored.