Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Tue Jun 17, 2008 at 20:24:31 -0700, Tom Brown wrote: > On Wed, 18 Jun 2008, Oliver Hookins wrote: > >> Anybody have any tips at all for this issue? I'm running out of ideas... > > somewhere in the 0.7 line, the same write barriers that are performance > issues in the 8.0 and 8.2 lines were introduced... I don't know if the > corresponding options were added for disabling it... The poor performance I am seeing is now only with DRBD connected, so it would seem to be network related. I would think write barriers would affect DRBD disconnected speeds. > > the the 8.0 line, 8.0.9 was the first to get it, and in 8.0.12 > the options for turning it off were added. You might try going to > an EARLIER or later 0.7 version... (earlier to avoid it, later to > be able to disable it...) > > Date: Sat, 24 May 2008 21:35:10 +0200 > From: Philipp Reisner <philipp.reisner at linbit.com> > To: drbd-user at linbit.com > Subject: Re: [DRBD-user] 8.x performance vs 0.7x --- was (not urgent) Request for DRBD Developers > > [...] >> >> Personally, I'm still on 8.0.8. Later versions at the time seemed to >> >> show _VASTLY_ reduced performance on my hardware, so I excluded it from >> >> the updates. I'm not experiencing any problems, so I'm sticking with it. > > That is due to that change: > > 8.0.9 (api:86/proto:86) > -------- > * In case our backing devices support write barriers and cache > flushes, we use these means to ensure data integrity in > the presence of volatile disk write caches and power outages. > [...] > > 8.0.12 (api:86/proto:86) > -------- > [...] > * Two new config options no-disk-flushes and no-md-flushes to disable > the use of io subsystem flushes and barrier BIOs. > [...] > > But please *read* the documentation about "no-disk-flushes" and > understand the implications before you set these options. > > # In case you are sure that your storage subsystem has battery > # backed up RAM and you know from measurements that it really honors > # flush instructions by flushing data out from its non volatile > # write cache to disk, you have double security. You might then > # reduce this to single security by disabling disk flushes with > # this option. It might improve performance in this case. > # ONLY USE THIS OPTION IF YOU KNOW WHAT YOU ARE DOING. > # no-disk-flushes; > # no-md-flushes; > > -Phil > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > -- Regards, Oliver Hookins