taking lvm backup

[Clint Byrum]

On Sep 28, 2010, at 1:39 AM, Tapas Mishra wrote:

> On Tue, Sep 28, 2010 at 11:11 AM, Clint Byrum <clint at ubuntu.com> wrote:
>> 
>> These are just the symlinks to the device nodes. If you look in
>> /dev/mapper, you'll see type "b" files nintendo-lvm1, nintendo-lvm2,
>> etc.
> 
> Yes I saw this is there.
> 
>> These block devices have their size defined by LVM, which you can
>> see in 'lvdisplay' from above as "LV Size".
> Yes
>> Do they have filesystems on them?
> Yes
>> For each one, try something like:
>> 
>> mount /dev/nintendo/lvm4 /mnt -o ro
> These filesystems are used to install Guest OSeS.
> So the filesystems are active.
> Do I need to shutdown the Operating Systems on these LVMs.
> Each LVM holds one Guest OS.
> It is a virtualization setup.
> 

If these guests are changing the filesystem, then you will probably
want to ensure that any databases or such are stopped or locked
when you back the files up.

As somebody else noted, they are probably partitioned, so that is
probably why you cannot mount them.

The simplest thing would be to just do the backups from inside the
guest OS's. Is there a reason you don't want to do that?

>> If it has a filesystem on it, that should detect it, and mount it
>> readonly, and you should be able to back up only what is *used* on
>> the volume, not the whole thing. Then just use whatever your favorite
>> backup method is.
> Ok.Do I not need to know the type of filesystem in these cases.
> 

As someone else stated, its likely that each volume has a partition
table on it. Given that these are essentially raw disks for guest
OS's, and not filesystems you created, I don't think its a good
idea to try and back them up from the host OS.