[linux-lvm] writable snapshots ? (a la timefinder BCV)

Heinz J . Mauelshagen mauelshagen at sistina.com
Wed May 22 03:44:02 UTC 2002

On Sun, May 19, 2002 at 11:22:59AM +0200, David Stes wrote:
> Hello,
> There is an option --snap to the lvcreate utility to create a read-only snapshot(frozen image) of a volume.
> Is there a possibility to quickly create a rw (read/write) snapshot of a logical volume ?

Beside other enhancements this is in 1.1-rcX which you can find
in CVS at www.sistina.com.

*** This is still in stabilization! Don't use it on production systems! ***

> I'm thinking here of applications in the style of EMC Timefinder BCV's (bcv = business continuance volumes).
> For example, I want to create a snapshot of a mounted volume running Informix.
> The snapshot of the mounted logical volume will be inconsistent, but it appears then to contain a 'crashed' instance of Informix, and when mounting the snapshot, I'd like to replay logfiles (do a recovery on the crashed instance) for which I need read/write access to the snapshot ...

You can do this and other things (for eg.: full fsck on the writable snapshot
to check a filesystems integrity).

> Thank you,
> David Stes.
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> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html


Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***


Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
Mauelshagen at Sistina.com                           +49 2626 141200
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