On Mon, 13 Dec 1999, Ken Hornstein wrote:
> >About four years ago when I first started managing this AFS cell we tried
> >using three database servers, but to send a new copy of the databases from
> >the master to the slaves took 40 minutes or so. FTP was faster than
> >whatever mechanism AFS was using to do the updates.
>
> It's my understanding that Ubik write performance decreases as you add
> database servers (which it really shouldn't, but from my looking at
> packet traces it seems there's some inefficiency in the rx_multi calls).
> However ... once you've elected a new database master, you just send
> incremental updates, and presumably you don't do that _that_ often (but
> I can see why 40 minutes is way too long for that if there were occasional
> glitches). I sometimes wish Ubik was smart enough to look through the
> database log and only send the changes since your last committed version
> when a reelection happens.
What log? :-)
Seriously, the transaction log is only good for local recovery if the
process or machine crashes in the middle of an update. Only the most
recent transaction is kept. Doing something else might be nice, but
would also be quite a bit harder...
-- Jeff
