[dm-crypt] dm-crypt "inverted" usage (i.e. exporting an "encrypted" image of a block device)

Ciprian Dorin Craciun ciprian.craciun at gmail.com
Thu Aug 1 18:17:00 CEST 2013


On Thu, Aug 1, 2013 at 5:46 PM, Erik Logtenberg <erik at logtenberg.eu> wrote:
> Maybe I also don't understand your use case well enough, but it seems to
> me that using dd over ssh would kinda do the trick, right?
>
> On the sending machine you use something like:
> # dd if=/dev/device | ssh root at receiving_system dd of=/dev/device
>
> Or if your sending machine doesn't have access to your receiving system,
> do something like this on your receiving system instead:
>
> # ssh root at sending_system dd if=/dev/device | dd of=/dev/device

    Nop.  `dd` over `ssh` would work only if I intend to dump (or
clone) the disk, at the block-device level, from one side to another.

    Meanwhile I need on-line, remote, read-write access.


> If you just want all your files over the network safely, use rsync over
> ssh. You say that you want to retain the native features of the
> filesystem itself, so as far as rsync doesn't have support for the
> specific features you're talking about (snapshots for example), just use
> dd to copy over the entire filesystem.

    Again this would work if I need to clone the disk, but this time
at file-system level.

    Moreover on this topic, I found that the best way to "clone" the
contents of a file system (minus any meta-data like ACL, extended
attributes, etc.) is via `cpio` over `ssh`.  It beats `rsync` as it
doesn't have to check anything on the other side and it buffers
nicely.

    Ciprian.


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