HP-UX 10 "reverse" mirroring

HP-UX 10 "reverse" mirroring

Post by Harm B. J. Ensi » Fri, 21 Jun 1996 04:00:00



Hello out-there,

On several of our systems, HP T500 running under HP-UX 10.01 we use logical
volume mirroring.
For those of you who are not so familiar with this here's an explanation.
The total diskspace is divided into logical volumes (LV). A LV is divided
into one or more file-systems. Each LV has an exact counterpart on another set
of disks which, through the mechanism of mirroring, contains an exact copy of
the original LV.
Every now and then we disconnect the mirror LV (lvsplit command). All further
actions will affect the original LV (let's call this LVo) while the mirror LV
(LVm) remains untouched.
When we reconnect the mirror (lvmerge command) LVm will be made equal to LVo.
Mostly this is a matter of one or two minutes!
This works perfectly but of course there is a new problem for every solution.

In the case that we have made a mistake on LVo we would like to have an easy
way to restore LVm to LVo or in other words a "reverse lvmerge".
The way we do it now is copy the files of LVm through 'cpio' to LVo.
(Ofcourse we first do 'fsck' on LVm and mount it on a dummy file-system)

We dropped the question with HP but they were rather quick with the answer
"impossible".

My question to you is: Has anybody dealt with the same problem or can you at
least help me on the way?

Greetings,
Harm