[DRBD-user] DRBD won't take 1G syncer rate

Dan Barker dbarker at visioncomm.net
Fri Aug 5 20:36:36 CEST 2011

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

I'm in the middle of a "verify the upgrade procedure" for drbd 8.3.10 to


Just for chucks, I did the dd command here, to see the performance I get.


root at Drbd0:/usr/src/drbd-8.4.0# cat /proc/drbd

version: 8.4.0 (api:1/proto:86-100)

GIT-hash: 28753f559ab51b549d16bcf487fe625d5919c49c build by root at Drbd0,
2011-08-05 14:01:40

0: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r-----

    ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0

root at Drbd0:/usr/src/drbd-8.4.0# drbdadm primary r0

root at Drbd0:/usr/src/drbd-8.4.0# dd if=/dev/zero of=/dev/drbd0 bs=1M

dd: writing `/dev/drbd0': No space left on device

5120+0 records in

5119+0 records out

5368508416 bytes (5.4 GB) copied, 499.712 s, 10.7 MB/s


Now, 11MB/s doesn't sound like much, but you have to remember:


a)      These are drbd virtual machines whose disks are connected (so the
I/O has to go through the wire to the other testing drbd in a different ESXi

b)       These target disks are actually virtual disks,

c)       Those virtual disks are on the "real" drbd machines (not yet
upgraded, actually, they are virtual machines in the same 2 ESXi hosts)

d)      The real drbd disks are using the same 1G nic to communicate.


So, your path was dd => raid card => 7.2Krpm disk = poor performance.


My path is dd => connected drbd device => vmfs filesystem => iSCSI initiator
=> iSCSI Target (virtual) => connected drbd device => vmfs filesystem =>
MoBo controller => 7.2Krpm sata disk = the same performance.


I'm pleased with my poor performance<g>.


BTW, there wasn't much in the "procedure" just:

cd /usr/src

wget http://oss.linbit.com/drbd/8.4/drbd-8.4.0.tar.gz

tar -xzf drbd-8.4.0.tar.gz

cd /usr/src/drbd-8.4.0/

./configure --with-km --prefix /usr --sysconfdir /etc --localstatedir /var

make clean all

stop drbd

make install

stop drbd

drbdadm dump, convert configs to new format


Worked a charm!





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