[rabbitmq-discuss] New Persister
matthew at lshift.net
Mon Mar 22 11:24:28 GMT 2010
On Sun, Mar 21, 2010 at 08:51:19PM -0500, Jeremy Dunck wrote:
> On Sun, Mar 21, 2010 at 5:58 PM, Matthew Sackman <matthew at lshift.net> wrote:
> > If you do choose to use the new persister, try to ensure the following:
> > 1) Try to make sure nothing else is writing to the disk that Rabbit is
> > using - Rabbit is pretty good at managing the position of the disk head,
> > but that tends to go wrong if other applications are writing at the same
> > time.
> Sorry, this sort of confuses me. I are you saying that in order to
> get best performance, Rabbit should be used with no apps using the
> same disk? Or are you saying app-level bugs might occur if Rabbit is
> used with other apps using the same disk?
> If you're just saying that sequential IO is faster and Rabbit tries to
> minimized seeks - sure, OK. If it's the latter -- that you're
> literally managing the drive head -- can you elaborate on that
It's the former. We mainly optimise by making sure that writes are
always append (so you should be able to get the full bandwidth of your
hard disc - fsync's permitting). The disk access patterns *should* be
sufficiently straight forward enough that OS disk prefetching and
caching works very well for reads.
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