Move LVM drive

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LearningCurve
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Location: Bradwell, Norfolk, UK

Move LVM drive

Post by LearningCurve » 2011/08/20 16:02:22

Hi,

At home I have a couple of CentOS 5.4 file servers each with system hard drives and separate data drives, all using LVM.
The system drive on server "A" has gone down and I would like to know if I take the data drive from that machine and put it into the other one, will it be picked up ok by the LVM search on boot up and be accessible.

I would then have to setup the user and group from the other server to match those on that drive, or use chown and chmod.

I have looked at the fora and LVM manuals but cant see what I'm looking for, could just be blind of course!

Thanks for your help,

Mike

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TrevorH
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Move LVM drive

Post by TrevorH » 2011/08/20 16:25:35

There'll be no problem with transplanting the drive and having the LVM volumes seen. What there will be a problem with is if you originally let CentOS name the volume groups then the name will be the same - VolGroup00. If you boot from rescue media and rename the volume group on the to-be-transplanted drive first then there shouldn't be a problem. If the volume group names are currently the different then you can skip this bit.

LearningCurve
Posts: 7
Joined: 2010/04/11 10:04:27
Location: Bradwell, Norfolk, UK

Re: Move LVM drive

Post by LearningCurve » 2011/08/21 07:52:58

Thanks for that, Load off my mind there!

LearningCurve
Posts: 7
Joined: 2010/04/11 10:04:27
Location: Bradwell, Norfolk, UK

Re: Move LVM drive

Post by LearningCurve » 2011/08/24 16:52:22

Not been that easy,

now, all my drives have named volumes except the system drives which are the usual VolGroup00-LogVol00 etc.
The data volumes are named MusicDrive etc. so should be no problem. I placed the drive into the other machine and it didn't find it.
I checked and everything seemed ok, but there wasn't an entry in fstab for it, (because it hadn't been detected), so to help things along I added the entry manually in the hope that it would then find it. Oh moron me.

When I restarted the machine it the failed because it couldn't see the file system for DataDrive.

I have booted from a livecd to edit the entry out but can't.
If i leave it to login as Centos then the system drive appears as VolGroup00-LogVol00 and I can open it, (Gnome desktop) but can't edit it as the drive is read only.

I then logged into the live cd as root but then the drive doesn't appear at all.

Back in as Centos I opened a terminal and su'd. went to the drive through /mnt/lvm/VolGroup00-LogVol00 and when I try to edit the file the whole drive is still read only.

How can I possibly retrieve the machine if I can't edit the problem out?

Also I transferred the DataDrive to my third server and that hasn't detected it either, in LVM it can see the physical drive but has not detected the logical volume or group.

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TrevorH
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Re: Move LVM drive

Post by TrevorH » 2011/08/24 18:54:43

If you have an error in your /etc/fstab and you are being dropped to a root command prompt then you need to run

[code]
mount -o remount,rw /
[/code]

to be able to edit and save the file. And you live and learn... next time you'll use a mount command from a root command prompt to try it out :-)

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