How to safely merge two slices on harddisk?
Malcolm Kay
malcolm.kay at internode.on.net
Mon Feb 9 04:12:27 PST 2004
On Mon, 9 Feb 2004 22:25, Malcolm Kay wrote:
> On Mon, 9 Feb 2004 13:46, Rob wrote:
> > Hi,
> >
> > I have a hard disk, on which I would like to merge two slices
> > into one single slice. The disk slices are as follows:
> >
> > /dev/ad1s1a 98M 43M 47M 48% /home/userB
> > /dev/ad1s1d 64G 45G 14G 77% /home/userA
> > /dev/ad1s1e 3.0G 2.5G 282M 90% /home/userC
> > /dev/ad1s1f 3.0G 1.0G 1.7G 37% /usr/ports
> > /dev/ad1s1g 3.0G 268M 2.5G 10% /mnt
> > /dev/ad1s1h 295M 295M -23.5M 109% /diskless_swap
> >
> > I want to merge /ad1s1f and /ad1s1g into one 6Gb slice.
> >
> > The merging should NOT destroy anything in the slices before
> > (ad1s1a, d, and e), but destroying the data in the one afer
> > (ad1s1h) is no problem.
> >
> > Is there a way to do this? What is the safest one?
> > (without having to backup the whole disk).
>
> Any manipulation at this level is risky. To do so without first
> taking a backup endangers all your data.
>
> But once you have the assurance of a backup you could copy
> all the information from /mnt into some new tree in /usr/ports.
> That is a tree copy of the content of /dev/ad1s1g to a new tree
> on /dev/ad1s1f.
> cp -Rp /mnt /usr/ports/newtree
>
> Having done that partition /dev/ad1s1g becomes free and you
> can rebuild the disk label using disklabel to eliminate the 'g'
> partition and extend the size of the 'f' partitition to take up the
> extra space. But first umount the 'f' and 'g' partitions.
> CAUTION
> ========
> Do not change the offset of 'f'. If 'g' does not physically
> follow 'f' on the disk then this is not going to work -- give up
> now!!!
>
> If all has gone well so far you should now be able to use growfs
> on /dev/ad1s1f to expand the file system to fill the partition.
>
> Remount the 'f' partition and you should be back in business.
>
> If you want to find what was on /dev/ad1s1g with the original path
> then
> rm /mnt
Should of course be:
rmdir /mnt
> ln -s /usr/ports/newtree /mnt
>
> If you are on 5.x then be warned that I have no experience with
> these versions of FBSD.
>
> And in any case I have never, myself, had occassion to use growfs.
>
> Malcolm
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