On 10. des. 2013 20:43, Jeff Siddall wrote:
> On 12/09/2013 11:20 PM, ToddAndMargo wrote:
>>> then you absolutely want to be running
>>> them against a snapshot rather than a live FS and LVM makes this easy.
>>
>> Never really cared for LVM.  Always used the direct partition approach.
> 
> Well, perhaps I can try to convince you some more.
> 
> Take another example of upgrading to a bigger disk.  Huge PITA if you
> use direct partitions.  Shut the system down and use a live OS or
> something while you move over all the data -- which could take hours or
> days depending on what you need to move.  If you are really obsessive
> you probably want to make sure nothing got lost in the move so there is
> a whole compare exercise after it finishes.
> 
> If you have LVM you simply install your new drive (assuming you can
> hotswap you don't even have to shutdown for that) run pvcreate, vgextend
> and then pvmove.  Some hours (or days) later it finishes and your data
> is magically on the new disk without even a moment of downtime.
> 
> A lvextend and a resize2fs (or whatever utility resizes the FS you use)
> and you can start using the extra space, still with no downtime.
> 
> That is pure sysadmin gold!
> 
> BTW: I also use LVM on my offsite backup disks.  I just use the same
> volume group/volume name on all the disks.  Works with LUKS also.

I'll even recomend fsadm, which makes resizing live filesystems even
easier and safer.  I've even done resize of / on a running system
without any issues.  The fsadm utility will do much of the filesystem
tasks for you, in a safe an controlled manner.

   # fsadm -v -l resize /dev/vg.../lv...  $NEWSIZE

If you're more cautious, you can add -n (--dry-run) and even do a 'fsadm
check' first.  This takes care of resizing all the needed pieces.  But
'fsadm check' can only be done on an unmounted volume, iirc.

I have not tried fsadm on a direct partition, though.  It might also
work there.

These LVM features can also be very useful if you're using virtual
machines with LVM, as adding and removing virtual drives on-the-fly is
very easy in such environments.


kind regards,

David Sommerseth