Works.
I'm afraid this email is tl;dr, but I'd still like to document the steps.
There is, in https://www.drbd.org/en/doc/users-guide-90/ch-admin-manual,
section 5.1.6, the paragraph
> Please note that the number of bitmap slots that are allocated in the
meta-data depends on the number of hosts for this resource; per default the
> hosts in the resource configuration are counted. If all hosts are specified before
creating the meta-data, this will "just work"; adding bitmap
> slots for further nodes is possible later, but incurs some manual work.
To be taken seriously ;-)
Section 5.19.1 explains this manual work (Works only if the cluster is down):
1. dump the metadata,
Somewhere I got the impression that I'd have to use 'drbdmeta' - rather difficult to use if you don't know exactly the parameters, no examples to be
found quickly - but of course this also works with 'drbdadm' :
drbdadm dump-md pool2 > pool2_md
Did not work at first
> Found meta data is "unclean", please apply-al first
drbdadm apply-al pool2
drbdadm dump-md pool2 > pool2_md
2.enlarge the metadata space, 3. edit the dumpfile,
In the dump, I increased the number "max-peers" from 2 to 3.
The subsequent restore-md failed with "Parse error in line 236: keyword 'bitmap'
expected, but end of file encountered",
so I also added at the end of the dump file
> bitmap[2] {
> # at 0kB
> 4055040 times 0x0000000000000000;
> }
4. load the changed metadata.
It seems there is no 'drbdadm restore-md', but running the dry-run-dump command
lets you figure out the parameters of drbdmeta:
drbdadm -d dump-md pool2
> drbdmeta 2 v09 /dev/drbdpool2/drbd2lv internal dump-md
so it must be
drbdmeta 2 v09 /dev/drbdpool2/drbd2lv internal restore-md pool2_md
This did not work either, because the increased metadata size would mean that
> Device size would be truncated,
Since this resource is a LV, I extended it by 5GB, ignored the xfs_growfs
warnings and got the 'drbdmeta restore-md' to work.
Now 'drbdadm attach pool2' did not work
> No usable activity log found. Do you need to create-md?
> 2: Failure: (127) Device minor not allocated
> additional info from kernel:
> unknown minor
That this should be an issue with the minor-count seems rather improbable, but
I still put the number to 100 in global_common.conf.
Finally,
drbdadm up pool2
worked, worked also on the new, fourth host. Sync is running.
And the resource even has survived the ordeal: made it primary, mounted it,
data are still there.
Cheers,
Thomas
On 14.01.2017 12:57, Thomas Roth wrote:
Hi all,
I'm on my first steps with DRBD 9. Seems I did not understand (many things) how
to add a new node to an existing cluster.
Atm I have a resource "pool2" on three nodes, it is UpToDate on all three,
primary on one node, mountable/usable there, all fine.
Now I want to add node 4. I have added this node to the config file and created
the resource on the fourth node.
When trying to adjust the resource on e.g. node 1, it fails with exit code 10:
node1:# drbdadm adjust pool2
pool2: Failure: (162) Invalid configuration request
Command 'drbdsetup new-peer pool2 4 --_name=node4 --protocol=C --sndbuf-size=0
--rcvbuf-size=0' terminated with exit code 10
drbdadm: new-path pool2: skipped due to earlier error
I have since set pool2 to secondary also on node1, no change.
And since this entire endeavor is a part of 'data rebalancing', and suspecting
some magic in the labeling given in the user guide, renamed the node in
the configuration from "node4" to "for-later-rebalancing" - no change either.
So how do I tell DRBD that there is a new peer in the game?
Regards,
Thomas
--
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Thomas Roth
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