MirrorDisk/UX and Alternate Links

[Adrian Hehir]

I am researching the benefits of file copy over host base mirroring for data migration.
Is host base mirroring using MirrorDisk/UX from an Alternate Links source to an Alternate Links destination volume supported on HPUX 11.11? I know its possible and as the HPUX server two HBAs are switch attached do not have to break the alternate link.
If MirrorDisk/UX is not installed can it be installed and then host base mirror existing Alternate Links LVs to new Alternate Links LVs?
Is it better to host base mirror between VGs or within a VG?
Is it better to file copy between VGs or within a VG?

[Mohanasundaram_1]

Hi Adrian,

I am not sure what your question is. MirrorDisk/UX provides software mirroring (RAID 1).

The alternate PV link is a LVM feature, wherein a LUN available to the host in 2 different paths can be added as primary link and alternate link. This will be in the same VG. This is independent of the MirrorDisk/UX.

Can you explain a bit more about your below questions?
---------------------------------------------
Is it better to host base mirror between VGs or within a VG?
Is it better to file copy between VGs or within a VG?
---------------------------------------------

I am sorry if I was not able to address any of your questions properly.

With regards,
Mohan.

[Adrian Hehir]

I wnat to do a Data Migration from an LV which uses Alternat Links to a new separate LV which also uses Alternate Links and then get rid of the original LV and PVs
.
I could use MirrorDisk/UX to mirror the data from an LV which also uses alternate Links to another LV which also uses Alternate Links. Is this supported on HP UX 11.11?

If possible then:
Is it better for the source and destination LVs to be in separate VGs or not when using MirrorDisk/UX?

If MirrorDisk/UX is not installed can it be installed and then host base mirror the existing LV?

If I cannot use MirrorDisk/UX then I will have to do a file copy or pvmove of the data from an LV which uses alternate Links to another LV which also uses Alternate Links. etc..
Should these two separate LVs be in different VGs or within a VG?

[Mohanasundaram_1]

OK.

Alternate links are for the PVs and not per LV. The Physical PV is only one but will be available to the host through 2 different paths. It is not 2 copies of your data, it is only 2 paths of the single copy of your data.

Mirroring is done at LV level and the mirroring is done within a volume group. It is not possible across the Volume groups.


By Migration, do you mean to move the data to another System? if so, you can just make this LUN available to the new server and do vgimport of the volume group and then you can use it without any hassles. If this is the case, let me know. I can give more steps on how to do it.

PVmove will move all the Extents from one disk to another, you cannot move a single LV from a PV.

With regards,
Mohan.

[Geoff Wild]

Yes - you can use mirrordisk/ux to migrate data.

It's not really alternate links - it's just setting up mirroring to those disks.

You add the disk as a mirror...

Example:

Say you want to copy the data in /dev/vg10/lvol1 from one disk array to another:

Currently, /dev/vg10/lvol1 is on /dev/dsk/c14/t6d0

lvextend -m 1 /dev/vg10/lvol1 /dev/dsk/c35t6d0

Once mirroring is done, remove the c14:

lvreduce -m 0 /dev/vg10/lvol1 /dev/dsk/c14t6d0

Rgds...Geoff

[Adrian Hehir]

I as asking the wrong question as I do not have MirrorDisk/UX installed. I will re-submit a new question