LV snapshot and filesystem sync

Hi all,

I apologize in advance in case this was already discussed, but I seem not to be able to find a clear answer, using the standard search engines.

The question is: when doing a snapshot of a LV volume, is it necessary to "sync" the filesystem above? Or is it done automatically?

If done automatically, does it work with all filesystems or only with some? Which?

Thanks a lot in advance,

bye,

piergiorgio