[DRBD-user] drbd storage size

Felix Zachlod fz.lists at sis-gmbh.info
Fri Oct 24 23:37:26 CEST 2014

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

looks like the backing device is not fast enough... do you use one drbd 
per physical device (and with physical I mean real hardware like a raid 
set) or are actually multiple drbd devices accessing the same disks?

If the second is true try syncing the devices one after the other.

please post output of

iostat -m 10 -xtc

Are there already other applications accessing the drbd devices from the 
upper layer on the primary? That usually causes drbd to reduce sync 
speed as the upper layers are preferred IIRC.

I have already seen sync speed of more than 400Mbytes/s with drbd 8.4 
over a 10GE link with magnetic disk backends so it is definitely 
possible, we synced a 16TB device once in only a few hours, but I can 
remember that sync speed dramatically decreased as load from the upper 
layer rose, which is quiet normal as the access is not linear anymore if 
this occurs.

regards, Felix

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