My reasoning for saying that LVM uses files on the system disk was
not just the lvmtab which on Fedora4 is /etc/lvm and it's files
(lvm.conf) but also the /dev/ mappings, EG:
/dev/mapper/my_vol-scanning1
1.8T 718G 926G 44% /data
I was concerned about the recreation of the /dev files.
As it turned out, the CentOS set-up (Anaconda) detected the volume
but it complained about /dev/sdb which is odd as I don't have one:
/dev/sda2 13G 5.1G 6.5G 44% /
/dev/sda1 136M 23M 106M 18% /boot
/dev/shm 1.1G 0 1.1G 0% /dev/shm
/dev/sda5 130G 1.1G 122G 1% /var
It didn't offer me the option of installing on the 137GB disk that is
the un-RAIDed system disk, least don't remember seeing it.
I wasn't confident enough to proceed so I rebooted to get a better
idea of existing disk arrangements. That lead to an fsck, at which
point I decided to call it a night as I did want to wait 2+ hours for
it to check the 1.8TB and then start the upgrade.
I'll have to try and find a longer window to do this in. I am not
sure about backing it up to a removable drive. I know it takes 4 LTO2
tapes and most of the weekend to back up the system. A restore would
take about the same.
I'll do an update around Easter I guess. Thanx for the responses.
Dermot.
On 14 Feb 2008 at 9:05, Adam T. Bowen wrote:
> Hi,
>
> I'm no expert on this subject, but seeing as nobody else has replied
> yet, I thought I would have a guess as to how this would work.
>
> Beginner wrote:
> > I want to upgrade, or re-install with CentOS and I don't want to have
> > to re-store all data on the RAID 5 volume but I am not sure that I
> > can because the LVM will use files from the system disk.
>
> Will it? We used to use LVM on HPUX and although there was an
> /etc/lvmtab file (think fstab), you could re-create it easily enough by
> running the lvscan command. This same command exists on Linux (although
> there is no lvmtab), and according to the man page it runs
> automatically. There is also a --mknodes switch which is nice.
>
> If you want to be sure that you can just slap a new OS on and it will
> automatically scan for and set up your logical volumes, try booting from
> a live Linux CD (Knoppix for example) and see if you can still see your
> logical volumes.
>
> Cheers
>
> Adam
>
> > Am I going to be able to maintain my existing LVM volumes during the
> > re-install? Is there a procedure to maintain LVM or store in after an
> > install or upgrade?
> >
> > The system is backed but if I have to re-create the partitions and
> > restore it will be off-line for several days and I would need to
> > schedule it for a public holiday.
> >
> > Any advice. Thanx,
> > Dp.
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