[mdlug] file copy

[Aaron Kulkis]

Adam Tauno Williams wrote:
> On Mon, 2013-12-30 at 09:40 -0500, Carl T. Miller wrote:
>> Adam Tauno Williams wrote:
>>> On Sat, 2013-12-28 at 10:31 -0600, Bob wrote:
>>>> I need to copy the contents of a hard drive to another, larger, hard
>>>> drive.
>>>> What are my options for most efficient/reliable methods?
>>> Attach the drive.
>>> Create a new physical volume ppvcreate] and add it to your volume group
>>> [vgextend]
>>> Move the logical volumes from the old physical volume to the new
>>> physical volume [pvmove]
>>> Remove the old physical volume from the volume group [pvremove]
>>> Grow the logical volumes [lvextend]
>> Adam, I love this answer because it means no downtime (assuming
>> that the new drive can be hot installed).
>
> And it preserves all meta-data, permissions, etc... which an rsync will
> *not* unless you are very careful.
>
>> However it does
>> require an existing volume group which may not exist in Bob's
>> environment.
>
> Hey, this is **2013**.  If you are not using volume management -
> reinstall now using volume management.

I don't use volume management unless I need it.

It's one more thing that can go wrong.  And worse, if the
metadata about a volume gets toasted, have fun recovering the
disk -- a simple couple-hour recovery can turn into multiple
days of stress.

Volume management is not without tradeoffs.

>
> It is 2013/2014 and people are still screwing around with partitions?
> In a word: "dumb".

Having done system restorations with and without volume management,
I can tell you that volume management is great ONLY if the volume
management data doesn't get damaged, and it can be nearly impossible
to recover a bad disk (not to mention multiple filesystems screwed
up by physical problems restricted to a small area of a platter.)

With old-fashioned partitions, that's much LESS likely.

Do I advise against volume management in all cases?  No.

But I only do if I have RAID mirroring of the root partition
(no RAID 5 or 6).  Anything else is inviting turning a small
glitch into a major disaster.