[DRBD-user] UpToDate resources not really up to date

[Thomas Roth]

Dear all,

question about what makes DRBD believe a resource is UpToDate:

I have a pair of servers with their DRBD resource on top of a logical volume.
On the secondary, I created a snapshot of the resource, created a suitable DRBD config, adjusted and synchronized it to a third server.

After full sync, I checked that the copy on the third server contains the files as I see them on the primary.

Then I removed the snapshot, removed all the files from that filesystem, wrote some other files and repeated the entire process.

Now, the sync between the snapshot on the secondary and the third server was instantaneous. Again I disconnected, made primary... and checked on the 
third server: it did not have the new files.

Mounting the snapshot on the secondary showed all the new files.

So DRBD did not recognize the changes in that file system. Obviously, I can do 'drbdadm create-md' and start a full synchronisation.

But I am interested to learn where the DRBD-visible changes (in the metadata, I presume) do usually occur, in contrast to this setup.


Best regards,
Thomas
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Thomas Roth
Department: IT
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