[linux-lvm] About Extending LVM size with Hardware Raid

[Piete Brooks]

> PATA disks are difficult.

Similar problems for SATA and SCSI ...

> There is a very slight chance of damaging the interface electronics,
> and motor driver electronics.

As below, that can be fixed ...

> There is also a chance of data loss, as it is difficult to guarantee that
> no write-behind cache is in operation.

If under RAID, use "raidsetfaulty" first, or otherwise make it quiescent.

> Finally, the operating system has to be able to disable an IDE device
> and redetect it,

There is code to do that, e.g. for laptop selectbays.

> including partition tables, etc

That works just fine, so long as no partition is in use, which it should not 
be.

> - somewhat of a grey area in the Linux kernel from my reading
> of the kernel sources. If that's changed, please let me know!

I re-partition disks "on the fly" fairly frequently.
I use RAID1 for all data, so I turn swapping off on the required disc, the 
"raidsetfaulty" and "raidhotremove" all the data partitions, then write the 
new partition tables which the kernels sees (check with /proc/partitions), 
then raidhotadd the partitions, mkswap and swapon, then repeat on the other 
disk, and bingo -- repartitioned without needing a reboot.
> There are cheap($30) hotswap caddies with a power switch which removes
> power from the drive and places the interface bus in Hi-Z state, but
> this still leaves the caching and operating system disable/redetect
> issues.
> 
> Cheers, glen.
> _______________________________________________
> linux-lvm mailing list
> linux-lvm at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/