[linux-lvm] lvm over loop device

Larry Dickson ldickson at cuttedge.com
Fri Sep 26 14:00:40 UTC 2008


If I may come to Geert's defense, his approach is more transparent: the PVs
are accessible from user space and their content arrangement is clear by
looking up the maps. Using snapshots puts everything into kernel space and
deep into mystery land (unless there is some user space way of
hand-manipulating COWs by sector number). I'm on the dm-devel list and they
literally have dozens of patches a day... like raging ocean currents under
your little, simple ship.

Unfortunately, I can't answer Geert's practical questions. Anyone?

Larry Dickson
Cutting Edge Networked Storage

On 9/26/08, Stuart D. Gathman <stuart at bmsi.com> wrote:
>
> geert Geurts wrote:
> > ps. for people interested, I'm trying to create a disk of allot of
> > small virtual disks so I can create a encrypted partition on for
> > instance gmailfs and minimalize up/download time on changes.
> > Pretty cool if it's possible no?
> I think a better solution might be to keep the encrypted fs on a single
> normal LV.  Take a snapshot and send to remote.  Keep the snapshot
> around.  On next upload, take a 2nd snapshot, and send the diff between
> the two snapshots.  The diff can be efficiently computed from the COW
> tables - accessible as dw-nn devices.  After sending the diff, delete
> the 1st snapshot and go back to "keep snapshot around".
>
>
>
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> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
>
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