[NTLUG:Discuss] LVM Span and data loss

[Ed Coates]

On Sun, 28 Nov 2004, Brett wrote:

> I've been reading through various docs and can't seem to find a
> definative answer on this...
>
> I have two 250 GB drives... I want span them so I have one big '500GB'
> drive for the samba server to share out to my home network... this
> will be used to store recorded shows and movies... sooooo ... if one
> of the 250 GB drives goes out on me, is all the data on the other
> drive useless like if I was using RAID 0 ? It seems to fill the drive
> up and then move to the next from some of the descriptions... but I
> may be reading it all wrong.
>
> Thanks for any help!
>
> Brett

Brett,

The answer to your question is yes.  There are a couple of options you can 
use when setting up your logical volumes in the volume group.  You can 
stripe them across the two drives, but the striping isn't like you're used 
to in RAID.  It is more for putting your data on more spindles, and making 
it a bit faster.  The other way you've found out already, where the data 
is contiguous and it fills up first one disk, and then on to the other.

If you lose one of the disks, then all is lost, so you better start making 
backups.  Just went through that with a client of mine recently.  Had to 
have the disk replaced, remade the volume groups and volumes, and restore 
data from backup.

Ed