Should the volblocksize be preserved after zvol replication?

[jakubjb]

Hi
On FreeNAS 9.3-STABLE we had an issue with zvol taking much more space then it was logically used on it. As we realized, the reason was in setting volblock size to 4K. After creating new zvol with volblocksize=recordsize=128K and copying all data to it, problem disappeared.
Now I need to replicate this zvol to another FreeNAS server (9.10.2-U1).
I'm in the middle of replication and I've just found out that the destination zvol has volblocksize of 8K, which is this version's default, I guess. It now behaves ok in terms of space usage/allocation.

Question is: why is volblocksize changed? I could swear that was not the case, when I replicated between two 9.3-STABLE servers.

 

[rs225]

I don't think zvol blocksize can be changed after creation. Datasets are different because the recordsize is actually fixed per file, so new files use the new setting.

 

[jakubjb]

I need to clarify, obviously. volblocksize did not change by itself on zvol.
I'm replicating zvol from source 9.3 FreeNAS server to destination 9.10.2-U1 FreeNAS server. The replication is in progress. On source zvol's volblocksize is 128kB, but on destination it's 8kB. I expected it to be the same, but it's different.
Is this a proper behavior?

All the story was to explain why I pay so much attention to this fact

 

[rs225]

I can't answer that particular question, except that it Will Work with mismatching volblocksizes. :)

 

[jakubjb]

Yep, it is working Thanks for confirming this. I hope there'll be no suprises with actual space usage. Thanks.