[DRBD-user] Unable to rate limit synchronization traffic with DRBD

Arnold Krille arnold at arnoldarts.de
Mon Jul 16 18:36:01 CEST 2012

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


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
> A.
> 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...

Have fun,

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20120716/f4c5bb47/attachment.pgp>

More information about the drbd-user mailing list