On 18/06/2008, at 7:48 AM, Binger David wrote:

> A Durus (FileStorage) database is just a file.
> New data is written only at the end of the file.
> You can backup the database by copying the file at
> any time.
>
> You could maintain a mirror of a Durus database by copying
> the Durus file at regular intervals, but this may be too
> slow and it may use more bandwidth than you would like.
>
> The latest release of rsync (I'm using 3.0.2) includes
> an "--append" option that seems to be excellent for mirroring
> Durus files.  It transmits only the new tail of the file,
> and skips verifying the contents of the part of the file that
> has already been transmitted.  The "--append-verify" option
> does the same thing, but it does verify whole file.
> I think you could run rsync frequently with --append,
> and perhaps occasionally with --append-verify to maintain
> a nice backup of a Durus database, and with minimal
> bandwidth.
>
> Are there alternatives that are just as good or better?

This is very appealing and timely. Other than somehow flagging when
packs have been done on the source database it would seem to be quite
usable. Have you done tests to see what happens when an --append is
run when the content has changed earlier in the file than the
destinations end? Is the keeping of that inline left up to the driver?

Regards,
Peter W.