topic Re: Remirroring issue in Operating System - HP-UX

Remirroring issue

Atul Goel — Fri, 12 Dec 2008 13:28:06 GMT

Suppose I have a mirrored system. I have taken out its mirrored disk (external and internal)
I have upgraded my system on the existing disk. But, it failed.
So I halted the system, swapped the disk (inserted the mirrored disk) and booted the system with mirrored disk
After system came up properly I inserted the disk (internal and external) which have upgrade failure
So now system has all the disk present in the /etc/lvmtab
My queries are
As all the disks are there so will system start mirroring itself? If yes then on what criteria will it start mirroring? I mean to say is there a possibility that It start syncing the mirrored disk (from which system was booted ) from disk inserted later on (with upgrade failure and latest data on it, lvm information is intact on it)? If yes, then how to avoid it.
If system will not start mirroring byself how to restart the mirroring from the active disk (from which system was booted ) to the stale disk (with upgrade failure and latest data on it, lvm information is intact on it) considering the fact that my system has two volume groups which are in cluster active mode on which LVM commands does not run when thy are in cluster active mode

Re: Remirroring issue

Torsten. — Fri, 12 Dec 2008 13:32:05 GMT

Sometimes after you did a

# vgchange -a y vg00

the system starts syncing automagically, sometimes not. It depends on the patch level.

If not, do a

# vgsync vg00

and you are done, because all the disk structure remains, only the contents changed.

The running disk will be sync to the newly inserted disk, because the data on it is newer.

Re: Remirroring issue

jaivinder — Sat, 13 Dec 2008 17:49:43 GMT

To do the activity on a system which have the mirrored root disks always use following procedure:
1.Boot your system with secondary boot disk
2. Split the volume group using
#vgsplit vg00
3.Remove the primary boot disk out of the slot
4. Perform your activity and boot the system with secondary disk, if your activity is successful then put the primary disk in the slot and just issue a
#vgsync vg00
If the activity got failed then reboot the system with the primary disk and remove the secondary disk, Once the booting is complete then insert the secondary disk and issue a vgsync command it will mirror the secondary disk with the primary disk.

Re: Remirroring issue

sujit kumar singh — Thu, 01 Jan 2009 09:32:07 GMT

hello Jaivinder,

is there a command called vgsplit as u have said in HPUX LVM or is it any script that u have called to assist the task.

I know lvsplit is there but not heard of the vgsplit commmand in HP-UX.

regards Sujit

Re: Remirroring issue

sujit kumar singh — Thu, 01 Jan 2009 09:40:04 GMT

Hello

all the LV level syncing of the data that takes place while we are doing syncing of the Mirrored Extents either using vgsync or using lvsync, is taken care of the Intelligent LVM itself that keeps the record in the mirror write cache and refers to the same while syncing the stalePEs.

So just give the command to sync and leave the rest to LVM, LVM is really reliable u need not worry for such cases where u feel old data is going to be sysnced.

Sujit