[DRBD-user] mount seconday read-write

[H.D.]

Lars Ellenberg wrote:
> whether or not this is noticable depends very much on the actual
> workload, and on the lower level io subsystem.

Right, but you always have to do backups and backups always cost
performance. I think one should plan systems with that in mind and
enough headroom from the beginning.

As the secondary box is usually less loaded than the primary, I prefer
to do it there.

We run PostgreSQL under heavy OLTP load and drop back from ~1500  to
~1150 TPS (test case, pgbench) during the secondary creating backup. So
yes, there sure is a big performance penalty, but as we have more than
enough headroom left, I have not bothered yet to move the snaps to
another PV.


-- 
Best regards,
H.D.