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

Digimer lists at alteeve.ca
Tue Oct 20 16:55:43 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.


On 20/10/15 07:07 AM, Joeri Casteels wrote:
> 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 A an async, C is sync. So you're probably hitting the network
limit on C.

https://drbd.linbit.com/users-guide/s-replication-protocols.html

> 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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> 


-- 
Digimer
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What if the cure for cancer is trapped in the mind of a person without
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