[linux-lvm] reduce size of snapshot - what is about previous reduce of file system ?

[Brassow Jonathan]

On Aug 28, 2014, at 7:50 AM, Lentes, Bernd wrote:

> Hi,
> 
> i have a lv which has a snapshot. Size of the snapshot was too big while creating. So I'd like now to reduce the size of the snapshot for being able to create a second one. man lvreduce says: Shrinking snapshot logical volumes (...) is supported as well. Ok, that's fine. But normally, before shrinking a lv, the file system has to be reduced. But does the snapshot have a fs ? I never ran a mkfs.xxxx on it. Can I just reduce the size without doing anything before ? Or do I have to provide a -r to lvreduce ?
> 
> Thanks for any information.

The (non-thinly-provisioned) snapshot fills up from beginning to end.  If it says it is 50% full, you should be able to reduce its size by roughly half.  Be sure to leave a good margin of space for snapshots to use, as they will become invalid if they are overfilled.

 brassow