[DRBD-user] Protocol A vs Protocol C performance issue?

Joeri Casteels joeri.casteels at intec.ugent.be
Tue Oct 20 13:07:48 CEST 2015

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


Dear All,


Doing a new set-up of DRBD on Ubuntu LTS 14.04 with stock DRBD 
When Setting to protocol A i get double the bandwidth as protocol C anybody an idea? not changing anything else of the settings except the protocol

PROTOCOL C:
d if=/dev/zero of=/dev/drbd0 bs=1M count=20000 oflag=direct
20000+0 records in
20000+0 records out
20971520000 bytes (21 GB) copied, 46.3583 s, 452 MB/s

PROTOCOL A:
dd if=/dev/zero of=/dev/drbd0 bs=1M count=20000 oflag=direct
20000+0 records in
20000+0 records out
20971520000 bytes (21 GB) copied, 23.8356 s, 880 MB/s

drbdsetup show r0 --show-defaults
resource r0 {
    options {
        cpu-mask        	""; # default
        on-no-data-accessible	io-error; # default
    }
    net {
        protocol        	C; # default
        timeout         	60; # 1/10 seconds, default
        max-epoch-size  	8000;
        max-buffers     	8000;
        unplug-watermark	16;
        connect-int     	10; # seconds, default
        ping-int        	10; # seconds, default
        sndbuf-size     	2097152; # bytes
        rcvbuf-size     	2097152; # bytes
        ko-count        	7; # default
        allow-two-primaries	no; # default
        cram-hmac-alg   	""; # default
        shared-secret   	""; # default
        after-sb-0pri   	disconnect; # default
        after-sb-1pri   	disconnect; # default
        after-sb-2pri   	disconnect; # default
        always-asbp     	no; # default
        rr-conflict     	disconnect; # default
        ping-timeout    	5; # 1/10 seconds, default
        data-integrity-alg	""; # default
        tcp-cork        	yes; # default
        on-congestion   	block; # default
        congestion-fill 	0s; # bytes, default
        congestion-extents	1237; # default
        csums-alg       	""; # default
        verify-alg      	""; # default
        use-rle         	yes; # default
    }
    _remote_host {
        address			ipv4 172.16.252.8:7789;
    }
    _this_host {
        address			ipv4 172.16.252.7:7789;
        volume 0 {
            device			minor 0;
            disk			"/dev/sdb";
            meta-disk			internal;
            disk {
                size            	0s; # bytes, default
                max-bio-bvecs   	0; # default
                on-io-error     	detach; # default
                fencing         	resource-only;
                disk-barrier    	no; # default
                disk-flushes    	no;
                disk-drain      	yes; # default
                md-flushes      	yes; # default
                resync-rate     	250k; # bytes/second, default
                resync-after    	-1; # default
                al-extents      	3389;
                al-updates      	yes; # default
                c-plan-ahead    	20; # 1/10 seconds, default
                c-delay-target  	10; # 1/10 seconds, default
                c-fill-target   	100s; # bytes, default
                c-max-rate      	102400k; # bytes/second, default
                c-min-rate      	250k; # bytes/second, default
                disk-timeout    	0; # 1/10 seconds, default
                read-balancing  	prefer-local; # default
            }
        }
    }
}




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