[Users] Re: vzmigrate standby mode

[Sterling Windmill]

The problem with the lsyncd approach is it doesn't guarantee filesystem
consistency. If you're running a database or any other application in the
container that has open file handles to data that is constantly being
manipulated, the data on the remote host isn't guaranteed to be consistent
at any point in time. Obviously this can be partially worked around by
creating application specific backups inside of the container using database
dump tools, etc.

vzctl chkpnt and restore guarantees consistency in that the state of the
container is dumped when the checkpoint is created and restored upon
restoration of said checkpoint. As long as the dump file and unadulterated
filesystem are available, restoration should result in a perfect copy of the
container as of when it was checkpointed. That being said, checkpointing
makes the container unavailable for a brief period of time and wouldn't be
ideal as a means of taking backups of production systems on a regular basis.

Checkpointing for this purpose would probably only make sense for a
container with data that doesn't change over time. A simple application
server that relies on an external database for instance.

lsyncd is interesting though, I haven't heard of it before and will
definitely be doing some research.

Best regards,
Sterling

On Fri, May 13, 2011 at 5:54 AM, Aleksandar Ivanisevic <
aleksandar at ivanisevic.de> wrote:

> Jean-Marc Pigeon <jmp at safe.ca> writes:
>
> > Hello,
> >
> >
> >       I think it will be very convenient to have a way to
> >       prepare/clone a VPS ready to start at moment notice
> >       (standby mode), a kind of action ready backup.
>
> We do it with lsyncd http://code.google.com/p/lsyncd/ that allows only
> changed files to be rsynced. Put /vz/private/veidt and
> /etc/vz/conf/veid.conf in it and you are all set.
>
> Much easier on the machines, no cron necessary and the backups can be
> made really close to production.
>
> [...]
>
>
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>
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