[Herefordshire] mount_r or mount within a mount within a mount etc etc

[Mark Broadbent]

John Hedges wrote:
> On Fri, Jul 01, 2005 at 03:13:48PM +0100, matt stone wrote:
> 
>>I guess i could google this but it's friday, i'm feeling lazy and i
>>thought it might generate some fun discussion :)
>>
>>I'm using Fedora core 3 on a box, it's got 2 disks, 1 system disk and
>>1 for file storage which is also set up as a samba share. I'm rapidly
>>running out space on the storage disk and want to add another disk to
>>it. To save creating a separate mount point and another samba share i
>>was hoping to be able to mount the new disk at the same point as the
>>current one.
>>
>>Soooo, is it possible to mount 2 separate disks at the same point?
>>and, if so, are there any known problems in doing this? or would i
>>just be better off cobbling a few more disks together to make some
>>raid type thing?

You can mount two disks at the same point but you'll only be able to see
the last mounted disk.

> I've never used it but LVM might be an answer. There is a howto here:
> 
> http://www.tldp.org/HOWTO/LVM-HOWTO/


LVM is definitely the answer here.  I use on one of our servers at work
(but for the inverse reason).  You could RAID-0 two disks together
however, if you wanted to add extra disks then you'd have to remake the
array.  For your purposes you would have two disks (physical volumes)
grouped into a single logical volume that can have a filesystem built
on.  The real advantage here is that if you say, upgraded one disk to a
larger size LVM could migrate all your data onto the newer disk and take
the old disk out of service.  It's very powerful and flexible but can be
a little difficult to understand all the concepts to start with, and
there's lots of command line tools and options. :-)

I would say if you wasn't to use it then you could use the followings steps:

1. Buy new disk
2. Backup data
3. Add new disk into a new LVM volume group
4. Create logical volume using created volume group
5. Create filesystem on logical volume
6. Migrate data from old disk to LVM based filesystem
7. Add old disk to LVM volume group
8. Extend logical volume to include additional space
9. Resize filesystem
10. Enjoy new space :-)


Thanks
Mark

-- 
Mark Broadbent <markb at wetlettuce.com>
Herefordshire LUG Master

Web: www.wetlettuce.com
LUG: www.herefordshire.lug.org.uk