[DRBD-user] DRBD9 Metadata on restored volume from snapshot to new host not valid

[Gianni Milo]

I'm not familiar with AWS but I have seen this behaviour when the backing
device size has changed (either grown or shrinked).
You may want to have a look at DRBD user guide, on the "resizing resources"
section.

G.


On Fri, 24 Apr 2020 at 21:50, Markus Marquardt <mmarquardt at axway.com> wrote:

> Hi,
>
> Environment: AWS EC2+EBS, CentOS 7.7
>
> I am doing a snapshot from a working DBRD disk set, so not from the DRBD
> volume, but the underlying "physical" disk, which is an AWS EBS volume in
> this case. The host from which the snapshot is taken is using DRBD 9.0.1-1.
>
> From this snapshot I create a new EBS volume and trying to use it on
> another AWS EC2 instance, which has a slightly newer DRBD version:
>
> # modinfo drbd
> filename:
>  /lib/modules/3.10.0-1062.18.1.el7.x86_64/weak-updates/drbd90/drbd.ko
> alias:          block-major-147-*
> license:        GPL
> version:        9.0.20-1
>
> Config is all default, ressource is like this:
>
> resource xxx {
>   device /dev/drbd0;
>   disk /dev/disk/by-id/nvme-Amazon_Elastic_Block_Store_volxxx;
>   meta-disk internal;
>   on node-1 {
>     address 10.0.0.1:7788;
>   }
>   on node-2 {
>     address 10.0.0.2:7788;
>   }
> }
>
> When trying to bring up the ressource, I get this error message:
>
> # drbdadm up xxx
> 0: Failure: (119) No valid meta-data signature found.
>         ==> Use 'drbdadm create-md res' to initialize meta-data area. <==
> Command 'drbdsetup attach 0
> /dev/disk/by-id/nvme-Amazon_Elastic_Block_Store_volxxx
> /dev/disk/by-id/nvme-Amazon_Elastic_Block_Store_volxxx internal' terminated
> with exit code 10
>
> ===> When doing as advised, I wonder about the following message:
>
> # drbdadm create-md xxx
> You want me to create a v09 style flexible-size internal meta data block.
> There appears to be a v09 flexible-size internal meta data block
> already in place on /dev/disk/by-id/nvme-Amazon_Elastic_Block_Store_volxxx
> byte offset 64424505344
>
> ===> So it is saying there _is_ metadata already present. So why is it not
> valid? Is this expected behavior when cloning a drbd physical disk to
> another host? Is it safe to create new metadata in this case?
>
> Do you really want to overwrite the existing meta-data?
> [need to type 'yes' to confirm] yes
>
> md_offset 64424505344
> al_offset 64424472576
> bm_offset 64422506496
>
> Found ext3 filesystem
>     62912604 kB data area apparently used
>     62912604 kB left usable by current configuration
>
> 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] yes
>
> initializing activity log
> initializing bitmap (1920 KB) to all zero
> Writing meta data...
> New drbd meta data block successfully created.
>
>
> Thanks much & regards
> Markus
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