Depends on the database / disk setup. For Mongo you should probably do an fsync/lock prior to taking the snapshot then release it, this will ensure the data on

Depends on the database / disk setup. For Mongo you should probably do an fsync/lock prior to taking the snapshot then release it, this will ensure the data on disk is in a consistent state. I don't think this is technically required with a single disk setup (at least with LVM, I've not used ZFS with mongo) but it's probably a good idea anyway and only causes a few ms hiccup.