[zfs-discuss] ...couple of issues/misunderstandings, hoping for clarification...

UbuntuNewbie chessdoter at googlemail.com
Tue Apr 10 08:51:31 EDT 2012

Hi list,

 while augmenting my use of the lovely zfs filesystem,i few questions/
observations arose:

- what does the snapshot.property "compression" mean? Isnt this really
a filesystem property? What is it for?

- when i moved a volume (zfs create -V...) around by means of the
rename sub-comand, i found: neither the link at /dev/zvol nor the one
at /dev/<poolname>/<volpath> got updated. I was able to work around
this one by exporting and reimporting the pool.

- after taking a snapshot from a volume, the used size for the volume
immediately doubles (1x volume + 1x per snapshot). This does not take
into consideration, how many changes - if any - are made to the
volume. Is this just a miscalculation or doesnt zfs use COW at the
block level only (as would some dedup-algorithm do)? That was
confusing and unexpected!

- After creating a pool with dev/disk/by-id names, exporting it and
reimporting, the names were replaced by names like sdb1. So what is
the benefit from finding the by-id names in the first place? I was
expecting those names to stay to avoid issues due to renaming of
devices depending on the connecting sequence or caused by connecting
different external drives to the same port.


cheeers, U.N.

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