Holger Parplies wrote:
> 3.) Reduced bandwidth requirement
> Because both ends understand the pooling mechanism, you have to transfer
> identical files at most once, and that only if they are not in the offsite
> pool yet.
I don't think you'd want to count on the pools being identical, and
in any case knowing that you have multiple copies on the sending
side would not necessarily mean the receiver already had a pooled
copy. The only sure bet would be to note duplicate files sent
within the same batch.
> You are not limited to the "previous backup" comparison, any
> identical file in the pool will do to save you the transfer.
Finding that identical file would be problematic. Assuming you
do the initial hash on the sending side, what do you do in the
case of hash collisions? You also don't have much chance of
finding large files with small changes as you would with a
normal backup comparing against the last run.
> If you trust the rsync digest stored in the pool file as a result of
> having checksum-seeding turned on (on both sides), comparing two pool
> files becomes really cheap.
I'd trust it to weed out mismatches, but not to establish an exact match.
> And if you compare it with *two* backups, you're obviously saving the
> client machines one of them (in addition to taking load off your offsite
> server).
Usually you have all night with nothing else to do.
> 5.) Reduced local hardware requirements
> You could keep a short local backup history to which the users have fast
> access and a long offsite history (seven years? :) to which no immediate
> user access is necessary (or even possible - depending on your
> requirements).
That would be equally true with a separate independent run.
--
Les Mikesell
[EMAIL PROTECTED]
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