[DRBD-user] Three way drbd

Mark Olliver mark at thermeon.com
Mon Jul 20 10:24:02 CEST 2009

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


I just went to start to try a three way replication but upon creating
the stacked resource on the primary i got the message below which was
unexpected. This primary machine already has several standard drbd
connections to another machine which are all working ok so i do not want
to effect these and it is one of these connections i am now trying to
mirror to a third machine, but it is a live disk and i cant afford to
lose the data. I am unsure where it is trying to create the metadata
here for the stacked resource?

root at eu-box9:~# drbdadm --stacked create-md therm1-U
md_offset 42951020544
al_offset 42950987776
bm_offset 42949672960

Found ext3 filesystem which uses 41943040 kB
current configuration leaves usable 41943040 kB

Even though it looks like this would place the new meta data into
unused space, you still need to confirm, as this is only a guess.

Do you want to proceed?
[need to type 'yes' to confirm] no

Operation cancelled.

Section from drbd.conf

resource therm1 {
  on eu-box9.xxx.com { device /dev/drbd2; disk /dev/sda8; address
x.x.203.101:7790; meta-disk internal; }
  on eu-box10.xxx.com { device /dev/drbd2; disk /dev/sda8; address
x.x.203.104:7790; meta-disk internal; }

resource therm1-U {
  stacked-on-top-of therm1 { device /dev/drbd12; address
x.x.203.101:7800; }
  on usa-box1.xxx.com { device /dev/drbd12; disk /dev/sda8; address
1x.x.203.112:800; meta-disk internal; }



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