About Filesystem freeze/thaw in freebsd

[Jordan Hubbard]

> On Feb 16, 2015, at 8:47 AM, Charles Sprickman <spork at bway.net> wrote:
> 
> Do the VMWare tools currently implement this?
> 
> VMWare doesnt complain when making snapshots, but I never found a
> way to verify its actually working.

You can’t do it that way with VMWare, at least not without some extra moving parts, since VMWare’s notion of snapshots and the host’s notion (UFS or ZFS, it matters not) are entirely disparate.  VMWare has some APIs that the host can optionally support (FreeBSD does not) to coordinate snapshots but other than that, again, no joy.

FreeNAS provides a “coordinated snapshot” mechanism with VMWare that basically calls out to VMWare (using its REST API) to snapshot all of the VMs on a given dataset, then takes a ZFS snapshot which encapsulates those VMWare snapshots, and destroys the VMWare snapshots afterwards (since they’re no longer useful).  It’s a little ghetto, but a whole lot better than purely uncoordinated snapshots where you have no idea if the VM is in a stable (known) state when you take the ZFS snapshot.

> How about Xen and popular Xen variations like Amazon and Digital Ocean?

Even less well understood / supported.

- Jordan