LVM Catch 22?

rosewood_tamper · #1 18th August 2005, 12:42 AM

I'm very much a Linux newbie so I hope this isn't too obvious...

I'm running Fedora Core 3 on a machine with 2 drives. The default configuration after install was that everything under root is mounted as /dev/VolGroup00/LogVol00. This volume group contains both my physical partitions (/hda2 and /hdb1).

What I would like to do is create 2 Volume Groups with one physical drive in each group. This way I can use one drive as a backup in case the other drive crashes.

I tried

pvmove /dev/hdb1 /dev/hda2

but was told that I need 915 allocatable extents. Ok, I figured that I could try to make some space using:

lvreduce -l 1000 VolGroup00/LogVol00

but I got scared from the resulting warning which made me think I needed to reduce the size of the root filesystem first. So I tried:

resize2fs /dev/VolGroup00/LogVol00 8000000

figuring that would give me 8 Gigs of free space allowing me to reduce the logical volume accordingly, but of course was told that I needed to unmount the root filesystem first!

So... how can I keep working on the machine while unmounting the root filesystem? Is there some way around this? A special boot up mode for working with LVM?

Any help would be greatly appreciated.

Peter

Iram Hernandez · #2 18th August 2005, 02:15 AM

You want to use ext2online. Support for this is built into the kernel.

rosewood_tamper · #3 18th August 2005, 02:45 AM

Quote:

Originally Posted by Iram Hernandez

You want to use ext2online. Support for this is built into the kernel.

Thanks for the reply...but I'm a bit confused. I just did a man on ext2online and it says that you can only enlargemounted filesystems, though you can shrink or enlarge unmounted filesystems. Am I missing something?

kc2005 · #4 31st October 2005, 09:09 AM

Boot with a live CD or, even better, with the installation CD in rescue mode. Choose the option not to mount your hdd and you'd be able to use the resize2fs command.

Here's a link where you can find a step by step procedure:
http://www.ibiblio.org/pub/Linux/doc...#recipesplitvg

rosewood_tamper · #5 31st October 2005, 03:43 PM

Thanks very much - that's just what I was looking for, I think. I'll give it a try.