Hi, Peter Mogensen <[email protected]> writes: > Hi, > > I have a database with close to 11 million entries and lately deletes > have started to get painfully slow. > I've set up a new server with a lot of improvements, but if anyone > have an idea about what the deciding factor for the performance > difference is, then I would be grateful. > > On the old server: > -16 cores. 42Gb RAM, entire database in memory > -XFS file system on (hw)RAID-1 > -Database and BerkeleDB log on same filesystem > -some, but not much load (~35 read waiters) > -time to delete 157 entries: 9 minutes. > > New server: > -16 cores, 48Gb RAM, entire database in memory > -ext3 filesystem on (hw)RAID-10 > -Database and log on difference disk > -no load. > -time to delete the same 157 entries: 6.2 seconds > > I'm aware that the new server has all the benefits, but even under low > load conditions, the old server is only able to delete an entry every > 3 seconds and there's orders of magnitude difference between 6 and 540 > seconds. > > My suspicion is that there's one of the above factors (XFS?, db/log on > same fs?) which get very pronounced when the database gets above a > certain size, since this slowdown for deletes seem to have accelerated > with the growth of the database the last few months.
To my opinion there are three factors which have influence on performance: - keeping db transaction logs on a different disk reduces writes on the database disk, - ext3 vs. xfs, xfs is known to be slower than ext3 in handling small files, - raid-10 provides a small gain in performance, if disk caching is configured properly. -Dieter -- Dieter Klünter | Systemberatung http://dkluenter.de GPG Key ID:8EF7B6C6 53°37'09,95"N 10°08'02,42"E
