On Thu, Aug 01, 2013 at 11:53:34AM +0100, Andrew Stubbs wrote: > If I have two partitions, /dev/sda1 and /dev/sda2, one btrfs, and > one ext4 (but I could convert it first), how can I merge them into > one filesystem without moving all the data onto an external device > and then moving it all back again? (I do have a backup, of course, > but transferring the data takes hours, maybe days.)
That's going to be the easiest option by far. > I'm left with this layout for historical reasons, and now the > smaller partition is close to running out of space. > > I thought of using "btrfs device add" and just living with the > untidy underlying devices, but an experiment with loopback > filesystems shows that any data on the new device is silently > obliterated (it might be nice if the docs mentioned this!) You would expect data in a different filesystem format to be integrated into an existing set of data structures? That would be... magic. :) > I've thought of shrinking the larger partition, creating a third > partition, and adding that to the smaller filesystem. This would > solve the free-space issue, but doesn't feel great. > > I've thought of using a temporary third partition as an > intermediary, but I don't have space to move all the data in one go. > > I've thought of using a clever partition manager to move the start > of the second partition, transfer some data, move it some more, > transfer some more data, but this seems like an equally lengthy > process. That's the other option I'd go for. > I could move the data from the smaller partition into the larger > one, then delete the first partition, and move the whole larger > partition forward, extend it, and fix up the fstab. That might be > less painful. > > Is there a cunning btrfs trick to do this? Can a btrfs filesystem be > extended "backwards", if you see what I mean? No, using gparted to move it backwards into the free space is your best option here. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- I don't know. I can't tell the future, I just work there. ---
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