Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
> However, no matter the way I configure DRBD, the throughput is limited
> to 100MB/s. It really looks like some hardcoded limit. I can reliably
> lower performance by tweaking the settings, but it never goes over
> 1Gbit (122MB/s are reached for a couple of seconds at a time). I'm
> really pulling my hair on this one.
...
> Output from cat /proc/drbd on slave :
>
> version: 8.4.5 (api:1/proto:86-101)
> srcversion: EDE19BAA3D4D4A0BEFD8CDE
> 0: cs:SyncTarget ro:Secondary/Secondary ds:Inconsistent/UpToDate C
> r----- ns:0 nr:4462592 dw:4462592 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0
> ep:1 wo:f oos:16489499884 [>....................] sync'ed: 0.1%
> (16103024/16107384)M finish: 49:20:03 speed: 92,828 (92,968) want:
> 102,400 K/sec
This is not throughput, but the initial synchronisation, as you note:
> Apparently initial synchronisation is supposed to be somewhat slow, but
> Not this slow... Furthermore it doesn't really react to any attempt to
> Throttle sync rate like
>
> Drbdadm disk-options --resync-rate=800M all
You're running on 8.4 - the "resync-rate" doesn't apply any more.
See
http://blogs.linbit.com/p/128/drbd-sync-rate-controller/
http://blogs.linbit.com/p/443/drbd-sync-rate-controller-2/
and the Users' Guide, especially 15.3:
http://drbd.linbit.com/users-guide-emb/p-performance.html
Furthermore, 8.4.6 has already been released ...
[ and if you want/need Pacemaker for newer Debian - LINBIT has them. ]