Latest TDB2 design and code...
tridge at samba.org
tridge at samba.org
Sun Sep 12 05:24:00 MDT 2010
Hi Ronnie,
> Snapshots have many more nice properties than just ctdb and ctdb recoveries.
>
> They would allow things like
> * rewind to content from previous snapshot
> * (if cheap) compute delta between snapshot x and snapshot y
> * compute delta between snapshot n and snapshot n-1 to allow backup or
> replication of deltas.
> * a series of deltas between n and n-1 allow for very compact
> representation of a series of point in time backups.
> * they provide an internally consistent point in time representations
> if the data, which could be used for backup
> or traversal purposes. traversing and/or backing the data up online
> without locking database.
yes, these are all basic properties of snapshots, but the question
still stands - what will Samba use them for?
How will users benefit from us having snapshots?
> Cheap snapshots have almost infinite number of use cases.
> I think snapshots are useful.
I love them in filesystems, but I also know just how much complexity
they add and just how much they can affect performance and prevent
optimisations.
I can see how they could be used in ctdb when you have wide area
clusters. That is a pretty esoteric use case for something that will
have a major impact on the code.
So what is another use case that would make it worthwhile to add this
to tdb?
Cheers, Tridge
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