[linux-lvm] exposing snapshot block device

[Tomas Dalebjörk]

Many thanks for all the feedback.

The idea works for those applications that supports snapshots.
Like Sybase / SAP Adaptive Server Enterprise, Sybase / SAP IQ Server, DB2,
MongoDB, MariaDB/MySQL, PostgreSQL etc..

Anyhow, back to the origin question:
Is there a way how to re-create the cow- format.
so that lvconvert --merge can be used.
Or by having lvconvert --merge to accept to read from a "cow file"

If that would be possible, than instant recovery would be possible from an
external source, like a backup server.

Regards Tomas

Den ons 23 okt. 2019 kl 08:58 skrev Gionatan Danti <g.danti at assyoma.it>:

> Il 23-10-2019 00:53 Stuart D. Gathman ha scritto:
> > If you can find all the leaf nodes belonging to the root (in my btree
> > database they are marked with the root id and can be found by
> > sequential
> > scan of the volume), then reconstructing the btree data is
> > straightforward - even in place.
> >
> > I remember realizing this was the only way to recover a major
> > customer's
> > data - and had the utility written, tested, and applied in a 36 hour
> > programming marathon (which I hope to never repeat).  If this hasn't
> > occured to thin pool programmers, I am happy to flesh out the
> > procedure.
> > Having such a utility available as a last resort would ratchet up the
> > reliability of thin pools.
>
> Very interesting. Can I ask you what product/database you recovered?
>
> Anyway, giving similar ability to thin Vols would be awesome.
>
> Thanks.
>
> --
> Danti Gionatan
> Supporto Tecnico
> Assyoma S.r.l. - www.assyoma.it
> email: g.danti at assyoma.it - info at assyoma.it
> GPG public key ID: FF5F32A8
>
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