LVM without losing data
 

Hi.

I would like to create a logical volume out of two physical volumes (/dev/sda1 and /dev/sdb1). Creating an LV per se is not an issue. What I'd like to do is leave the data currently on /dev/sda1 intact so they can be accessed after the LV has been created. Is it possible?

The reason I want to do it is because the hard disk for /dev/sda1 is almost full (420/500 GB), and the computer has no space to add an extra disk (except for the one for /dev/sdb1) to back up the data.

Any help/feedback would be appreciated.

sorry no way!!
you can check with more advanced storage space managemet tools like EVMS
http://tldp.org/LDP/EVMSUG/html/EVMSUG.html

You could use a usb disk to temporarily move the data while making the switch. Personally I avoid LVM like the plague. The are fine until something goes wrong with them. Then life gets really ugly. If any drive fails in a LVM you loose everything that is stored on the entire LVM.

I could, except that we're talking about 400+GB of data. I never thought about your point on failure, though. That's actually scary. I'll need to think twice about LVM now.

You can get usb disks up to a TB (at least that I have seen).

It is fairly easy to just add another disk. It does not have to be part of a LVM. As far as setup goes it is about the same as having a separate /home partition (seamless).

Wow, that's one big USB disk... I've never seen anything like that before. I guess I'm behind. :study:

It's not flash - it's a USB case for IDE 3.5'' HDD.

Ah, okay. I was wondering what a 1TB USB flash drive would look like.

Thanks!

Ever heard of backups ???.

I back up the most critical files on a regular basis, but not the entire 500GB. Most of the data I have on it are something I'd much rather not lose but could shrug off if a catastrophic failure should occur.

I do likewise - my systems I am prepared to re-build at any time in need. For user data I use separate partitions; backed up of course - I have not determined how I can conveniently use LVM if it all goes to hell.
Hardware RAID and EVMS would be my preferred solution probably.

Have you looked at unionfs/aufs ???.

I think most of us just back up "have to" stuff and hope for the best for the rest. Once you get much over 300gig life starts getting pretty tough.