On Tue, Sep 14, 2010 at 09:06:24PM +0200, Arkadiusz Miskiewicz wrote:
> On Tuesday 14 of September 2010, Fabricio Archanjo wrote:
> > Hey all,
> > I just trying delaylog in my server that has a mysql database. When
> > i monted my /var/lib/mysql with delaylog option, it showed me:
> > "Enabling EXPERIMENTAL delayed logging feature - use at your own
> > risk". Ok, i know it's experimental, but what kind of problem could i
> > have using delaylog?
Basically you could hit a race or lockup in the code under high stress
or unusual workloads. So far we just had one possible lockup under very
high dbench load.
> ... and what problems in case of system hang or power loss when compared to
> nodelaylog mode?
The same as with the old log code - if you crash recently written data
might be lost. Unless a really severe bugs shows up (in either the old
or new code) that only includes data since the last fsync/sync. The
quantitative difference is that a lot more metadata is now cached in
core, so on a crash you can lose more recently written but not synced