[DRBD-user] Limit Syncer Speed

Jasmin J. jasmin at anw.at
Thu Dec 15 06:42:21 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.


 > I would advise that you refer to the documentation, what you are asking for
 > already exists:
For my tests I had this configuration:
                 c-plan-ahead 5;
                 c-delay-target 20;
                 c-max-rate 35M;
                 c-min-rate 4M;

                 # will overrule c-delay-target, but seems to be better
                 # concerning linearity of the used network bandwith
                 c-fill-target 18M;

                 max-buffers 8000;
                 max-epoch-size 8000;
                 sndbuf-size 512k;
                 cram-hmac-alg sha1;
                 shared-secret "xxxx";
                 verify-alg md5;
                 protocol A;
                 on-congestion pull-ahead;
                 congestion-fill 2G;
                 congestion-extents 2000;

And I observed the slowdown of the write as described in my initial post.
Either "pull-ahead" doesn't work, or another configuration interferes with
this setting, or we didn't understand the description or I simply was too
stupid and fooled myself to make the test right.
But I can re-test it.

My goal would be to limit the syncer speed to 300MBit/s AND to keep the
write speed at 130MBit on my local disk and let the peer going out of sync
until the bulk write is done and re-sync does its job.
And yes, I know the data will be inconsistent for this short period.


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