[DRBD-user] Slow resync

Ricardo Branco ricardo at wenn.com
Tue Jan 5 14:00:41 CET 2016

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Wow so that was a massive speedup.
Resync speeds are up around 300-400MB/s, still way below peak disk/ethernet speeds but I am being limited here by the 
SSD read cache on our LSI controller, shame it does not understand massive streaming reads and bypass the cache drives.
Writing a file to disk (drbd disconnected) hits around 1-2GB/s, reading with SSD cache enabled is around 300-400MB/s and 
off it then goes up to 1-2GB/s.


Emmanuel Florac wrote on 05/01/2016 10:53:
> Le Mon, 4 Jan 2016 16:48:53 +0000
> Ricardo Branco <ricardo at wenn.com> écrivait:
>
>> Resync seems to always be limited to max 40MB/s, if I am doing both
>> of my resources at the same time then both are at 40MB/s (total 80M),
>> but never goes above this.
> Yes, this looks like some default settings. Apparently you're using all
> defaults, with some obsolete settings added (won't do any good), here's
> the config I'm running (~700 MB/s throughput on 10GigE):
>
> global_common.conf:
>
> global {
> 	usage-count no;
> 	# minor-count dialog-refresh disable-ip-verification
> }
>
> common {
> 	handlers {
> 	}
>
> 	startup {
> 		# wfc-timeout degr-wfc-timeout outdated-wfc-timeout
> 	wait-after-sb # wfc-timeout 20;
> 	}
>
> 	disk {
>          	on-io-error detach;
> 	 	no-disk-flushes ;
> 		no-disk-barrier;
> 		c-plan-ahead 0;
> 		c-fill-target 24M;
> 		c-min-rate 80M;
> 		c-max-rate 720M;
> 	}
> 	net {
>          	max-buffers             36k;
>          	sndbuf-size            1024k ;
> 		rcvbuf-size	       2048k;
> 	}
> 	syncer {
>          	rate                    4194304k; # bytes/second
>          	al-extents              6433;
> 	}
> }
>
>
> cluster.res:
>
> resource rd0 {
> 	protocol C;
> 	on cl1 {
> 		device /dev/drbd0;
> 		disk /dev/sda4;
> 		address 192.168.42.1:7788;
> 		meta-disk internal;
> 	}
>
> 	on cl2 {
> 		device /dev/drbd0;
> 		disk /dev/sda4;
> 		address 192.168.42.2:7788;
> 		meta-disk internal;
> 	}
> }
>




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