Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Fri, Dec 11, 2015 at 09:04:28AM +0100, Harald Dunkel wrote: > Hi Lars, > > On 12/04/2015 05:04 PM, Lars Ellenberg wrote: > > > > You are not supposed to disable the resync controller, > > you are supposed to correctly use it. > > > > https://blogs.linbit.com/p/443/drbd-sync-rate-controller-2/ > > > > ... you should: > > > > * set c-plan-ahead to 20 (default with 8.4), > > or more if there’s a lot of latency on the connection (WAN > > link with protocol A); or less, if you want to have it > > react faster to changes > > > > * leave the fixed resync rate (the initial guess for the controller) > > at about 30% or less of what your hardware can handle; > > > > * set c-max-rate to 100% (or slightly more) of > > what your hardware can handle; > > (the default is 100M, which was the effective limitation in this case) > > > > * set c-fill-target to the minimum (just as high as necessary) > > that gets your hardware saturated, if the system is otherwise idle. > > > > Respectively, figure out the maximum possible resync rate in your > > setup while the system is idle, then set c-fill-target to the > > minimum setting that still reaches that rate. > > > > And finally, while checking application request > > latency/responsiveness, tune c-min-rate to the maximum that still > > allows for acceptable responsiveness. > > > > You may need to adjust max-buffers and/or tcp send/receive buffer > > sizes as well. > > > > Sorry to say, but this is way too complex for an ordinary user > (speaking just for myself, of course). It gets even more complex > if you have several drbd resources. The man page doesn't help in > this case, either. > > How about some recommendations with real numbers? > > BTW, the man page for version 8.9.4 mentions that the default for > c-plan-ahead is 0. If I got this correctly this means that the > dynamic resync speed controller is disabled by default. Is this > correct? No. -- : Lars Ellenberg : http://www.LINBIT.com | Your Way to High Availability : DRBD, Linux-HA and Pacemaker support and consulting DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. __ please don't Cc me, but send to list -- I'm subscribed