Re: how can I add disk space?

[Adam Scriven <scriven@lore.com>]

On Fri, Oct 06, 2000 at 04:20:19PM +0200, Markus Stahl wrote:
> And what do you mean with "LVM is more flexible" (and by the way 
> what does RAID and LVM mean?)?

RAID stands for Redundant Array of Inexpensive Drives (Disks?)
LVM stands for Logical Volume Management (IIRC).

I've done quite a bit of research on this subject, since I too have a multiple
drive "problem", and this is what I've come up with.

RAID combines multiple partitions (not necessarily full drives) into one
single drive.  Depending on the type of RAID that you use, you can have some
sort of redundancy (RAID 5), or just combining your drives (RAID 0 is Striping,
which is what does this, IIRC), or you can get pure backup with mirroring (RAID
1, again IIRC).

LVM is a much more flexible method, because it uses smaller partitions, and
can move them around on the fly.  I haven't done as much research in this
department, but it does seem very interesting.  Basically, you setup partitions
on your drives, and allocate those partitions to "Logical Volumes".  Then
you mount your filesystems (/usr, /home, /var, ETC.) onto a logical volume.
If you need more space, take space out of one LV, and move it to another,
no problems.
I'm very curious about LVM, since I've got a number of 15GB drives in my
fileserver that are separate right now, that I'd like to combine into a usable
whole, but RAID 0 doesn't give me much redundancy.
What is the redundancy in LVM?  Is there any?
if you lose a LV, do you lose everything (A La RAID 0), or is there some
method of rebuilding that information (A La RAID 5)?

I hope this helped (and was correct, please tell me if it wasn't!).
Adam