Is it possible to access data on a disk in removed state ?

[TSch]

Hi everybody,

there's something in my coursebook concerning disks in a removed state, that I don't understand:

It says: When a disk is in a removed state you can't access the data on that disk even after a forced varyonvg.
But it also says that if you need to exchange a disk because of a hardware error you'll have to put it into a removed state and then migrate all data that isn't corrupted to another disk.... What I don't undertand is: How can I migrate data, when according to the first statement I'm unable to access any data on a disk in removed state ??

Can anyone help me with that ?

Thanks in advance !

Regards
Thomas

 

[gileb]

Hi,
Moving the pv in remove state (via chpv command) can be done only if pv is not active (no mounted fs on it) which means that pv certainly is already in missing state. If no fs is mounted , you can not do very much things and certainly no useful backup of data (you may still do some dd on the lvs but i dont think its the best way to backup data). Anyway, even an lquerypv -h /dev/hdiskxx can list data on an offline disk

hope that helps

 

[vickersdc]

I think there are two separate issues here:

1. When you forcibly vary on a VG you should get access to data (although as a result of forcing it data inconsistency may result and there is no guarantee of that access).

2. With a failing disk (as opposed to a completely dead one) you can use the migratepv command to move LV's to another PV (although there are considerations of the PV has a blv on it).

The disk should be removed from the VG properly to ensure that entries for the [removed] disk are not still in the ODM (by reducevg and rmdev -dl).

Cheers,
Dave V.