[linux-lvm] Query regarding conversion of root partition to LV

[Prateek Donni]

Hey George,
     I am trying to make use of LVM's existing mirroring feature to
protect data from disk failures.
So i want to convert the original root into an LV.
I thought of making a block device with the free space(as in which is
allocated inside as root )  and create a PV of the same. can this help
? then on the second disk which may have unallocated space, i create
another PV and mirror a volume across it using LVM features.
I dont want to make use of RAID and i have to have my application run
w/o a reboot.

Any suggestions which you can give me considering the above constraints ....


Thanks Prateek



On Wed, Feb 4, 2009 at 7:53 PM, Georges Giralt <georges.giralt at free.fr> wrote:
> Prateek Donni a écrit :
>>
>> I have a fedora 9 installation with two partitions swap and /
>> partition. Now i want to mirror the files on the root partition to
>> another disk using LVM mirroring. Since i dint make root on a LV and
>> have no allocated space left so i am thinking of using the free space
>> on the root partition as a block device that can be converted into PV
>> and then mirrored after making it a LV.
>> Is this feasible?
>> Can someone let me know wht can be done?
>>
>> Thanks
>> Prateek
>>
> Hi Prateek !
> IMHO this won't work.
> As you spoke about mirroring, you can do this :
> 1) add another disk to the system (ideally same size of the original one)
> 2) partition it as :
>        part #1 used as /boot (about a 100 MB, Ext2/3 FS )
>        part #2 the remaining of the disk tagged as LVM.
> 3) boot your system under Fedora 9 and using LVM mamger create a PV ont the
> second partition, then a VG on the PV and then as much LV as you need. Do
> not forget to create the swap LV.
> 4) Format and temporary mount each LV ont the filesystem, recreating the
> correct layout but under, say, /mnt.
> 5) copy the data using a command like : cd / && tar cf - . |(cd /mnt && tar
> xf -)
> 6) under the /mnt layout correct the Grub menu file, then using this as the
> root with chroot, re-run grub-install.
> 7) boot under the new disk and test your system.
> If fine,
> 8) create the same partition layout on the old disk as the new one and
> create 2 software raid 1 (mirror) using mdadm, one for the first partition
> used as /boot , the other one for the PV.
> 9) synchronize the md.
> Enjoy.
> Be carefull and read the man pages before proceding. A complete backup may
> prove usefull, also.
> Hope this helps.
>
> --
> If the only tool you have is a hammer, you tend to see every problem as a
> nail.
>                Abraham Maslow
> A British variant :
> Any tool can serve as a hammer but a screwdriver makes the best chisel.
>
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