there are inherent problems with any filesystem like xfs, ext2, reiser...
namely, you cant grow/shrink a filesystem without the sysadmin doing a lot
of work. -- copying all the files off the partition, repartitioning, copying
files back. Eek, maybe even a worse case is what happens when /home is 10G
and tomorrow it needs to be 500GB? wish you could make /home span across
multiple disks eh?
What LVM does is it sits between the physical disks (or hardware raid array)
and XFS (or ext2 or reiser). The filesystem thinks it resides on an
honest-to-god disk/array, but in reality, xfs is talking to a virtual disk.
If you need to make your /home 'partition' larger.. say, if a lot of your
users like to download .mp3's :-), what you can do is tell LVM to make the
/home partition bigger. Of course, just because the disk size magically
changed from 5G to 10G, doesn't mean that xfs,ext2,etc knows about it. so
then you also have to tell xfs to resize the filesystem.
I've set up an NFS server, serving about 10 client machines. Each client
has its own 'space' on the NFS server... i've allocated space for my WWW
server, some space for a development server, some for homedirectories..etc
etc. I don't know which partition will eventually run out of space
first... and it'd really suck to take down my hefty NFS server to
repartition -- actually, it would royally suck because if the NFS server is
down, all 10 of my client machines cant operate either....
I'd really recommend you play with it, i think you'll like it. Just
remember that you have to ste up the actual disks for LVM (using the
pvcreate command) [Physical Volume] (this is performed on something like
/dev/hdb1). Once you have all your disks initialized, you put them into a
disk group which can be thought of as a "pool of storage space" by using the
vgcreate command (if you name the group "data_group", then you'll see a
/dev/data_group directory). And then the last step is to make a logical
volume--this is the actual block device that you'll tell mkfs to format.
You use the lvcreate command and you specify how much space this new
virtual-disk will have.. and which volume-group to. (you'll get something
like /dev/data_group/lvol1 -- which you can do a mkfs on and mount it).
--- Eric Peters <eric@xxxxxxxxxx> wrote:
> At the risk of sounding ignorant, what's LVM and how
> does it effect XFS :)
>
> Thanks!
>
> Eric
>
> ----- Original Message -----
> From: "Fang Han" <dfbb@xxxxxxxxxxxx>
> To: <linux-xfs@xxxxxxxxxxx>
> Sent: Wednesday, August 15, 2001 7:53 PM
> Subject: LVM 1.0 is released
>
>
> >
> > Hi, LVM 1.0 is announced, When XFS cvs tree will
> upgrade to that version?
> >
> > I think LVM 0.9.1_beta6 is the stable version
> working with XFS. Is it
> right?
> >
> >
> > Dan
> >
> >
>
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