arnold at arnoldarts
Jul 16, 2012, 9:36 AM
Post #3 of 3
Re: Unable to rate limit synchronization traffic with DRBD
[In reply to]
On Monday 16 July 2012 07:53:18 rahulcs wrote:
> I am a new user of DRBD. I am trying to use DRBD to send disk updates to a
> backup disk at a configuration rate in an asynchronous manner. From the DRBD
> documentation it looks like i should be able to do this if i use Protocol
> But when i write a file onto the partition that is being backed up by DRBD i
> continue to see that the network traffic is very high inspite of me setting
> the sync rate.
> What am i doing wrong ?
The sync-rate is for when drbd has detected that there is a difference between
the peers and it needs to sync these. For example after a downtime of the
secondary while the primary was used. Or when drbd checks its whole disks and
syncs the differences.
That is totally independent from the normal writes, which are done on the
secondary at the same time as on the primary. Even with protocol A!
The protocols only report different states as "written": While C only reports a
block as written after local and remote disk have actually written the data to
disk, A reports a block as written when the local disk is written and the same
data has left the local network-interface. Still all this gets written on the
secondary the same as on the primary.
When you want to limit the transport or have a small connection and need
something to buffer the write-requests, talk to linbit about drbd-proxy...