Subject Re: [Firebird-Architect] Firebird improvement suggestion
Author Alexandre Benson Smith
Tim Haynes wrote:

>Hope this is the right place to post an improvement suggestion. Apologies
>if I am mistaken.
>A feature which looks very attractive at first sight is the shadow database,
>maintaining an immediately available copy of a database on another volume to
>allow recovery from disk failure. I can see how this might have been needed
>once, but with RAID now incredibly cheap this seems to be rather defunct.
>What would make it very powerful is if the shadow database volume could
>reside on another computer, allowing immediate recovery on an alternate
>machine in the event of the failure of the primary server. This is what I'm
>looking into, as I really need a resilient solution. The Firebird Book
>indicates that this is possible using NFS, but sadly appears to be disabled
>for Windows shares. Also, as far as I can see, any interruption to the
>connection would destroy the shadow. I also suspect that the (relatively)
>slow network write could really slow things down.
>What would be REALLY useful would be to queue shadow database updates so
>that a shadow can be effectively maintained on second machine. I would
>imagine that this could be fairly easily done by queueing via disk files.
>For example: at present new/changed blocks of data are written directly to
>the shadow database. Instead, the database server could simply write each
>to a separate file, with a suitable sequence number and block number in the
>filename. A process on he second machine could poll this disk area (via
>nfs, windows share, ftp etc) and simply merge the new blocks of data into
>the shadow database file held on that second machine. OK, maybe that's a
>litle simplistic (too many small files) but something similar should work -
>perhaps a file per transaction or somesuch.
>Any mileage in something along these lines? Right now the whole
>resilience/failove thing is a big decider in my database choice and Firebird
>seems so very close...

Maybe the new backup tool for FB (NBackup) coud solve your problem.

This new tool allow diferential/incremental back-up's, so a small file
could be transfered (ftped) to another machine and restored there, this
way you could have a almost up-to-date second database.

Don't know if it's what you are looking for.

see you !


Alexandre Benson Smith
THOR Software e Comercial Ltda.
Santo Andre - Sao Paulo - Brazil

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