Migrating from base to OpenZFS: GELI drives, send/receive, and sysctls/loader.conf

[Lorenzo Perone]

Am 15.02.21 um 21:08 schrieb Freddie Cash:
> On Mon., Feb. 15, 2021, 9:37 a.m. Lorenzo Perone,
> <lopez.on.the.lists at yellowspace.net
> <mailto:lopez.on.the.lists at yellowspace.net>> wrote:
> 
>     Hi All,
> 
>     I have followed regularly the development of openzfs for FreeBSD and I
>     guess I'm ready and eager to give it a first try on a 12.2 updated
>     system by using the port.
> 
>     Particularly watching the (now a little outdated, but still good) talk
>     by Alan Jude @ EuroBSDCon 2019 was very encouraging.
> 
>     What I'm planning as a first run is:
> 
>     On the same machine:
> 
>     - Boot with openzfs_load instead of zfs_load
>     - Import the "base" created pool with openzfs
>     - Create a new pool with openzfs
>     - Send/Receive and/or rsync data from the old to the new one
> 
> 
>     A few questions arised for which I didn't find an answer yet in the
>     official documentation.
> 
>     1) Will a pool on GELI drives import well with openzfs too? I'd assume
>     yes, why shouldn't it. Just asking to correct me if there are any
>     precautions I should be taking or surprises to expect.
> 
>     2) Will the "old" settings be honored by openzfs, such as
>     vfs.zfs.arc_min, vfs.zfs.arc_max in /boot/loader.conf?
> 
>     3) Is there an openzfs_enable as opposed to zfs_enable in rc.conf (to
>     import/mount pools at boot)? Or is zfs_enable just compatible?
> 
>     4) As far as I know, it should be possible to send/receive data from an
>     unencrypted dataset to an encrypted one. Is this advisable from an "old
>     base" zfs dataset (not encrypted, on geli) to a new openzfs one
>     (encrypted at the dataset level), or should we resort to rsync?
> 
>     5) What's the actual current status on extended attributes? Will they be
>     retained in a send/receive from FreeBSD-"old" to FreeBSD-OpenZFS? I have
>     a few shares on that machine where macs have "dropped" their EAs via
>     AFP/SMB, what should I expect?
> 
>     Thanks a lot for any attention by people who know this right away,
> 
> 
> If this is a boot pool, create a new boot environment and reboot into it
> before making any changes. In the new BE, install the port, update
> loader.conf and test things out. So long as you don't do a "zpool
> upgrade" or enable any new features, then you can always change BE at
> the loader menu to revert back to the working config.

No, for boot SSDs I usually resort to UFS on gmirror + gjournal... ZFS
on root is appealing (boot environments and rollbacks..) but until now
booting has been something I have rather kept out of ZFS, legacy or not.
Maybe one day.. :)

> Doing it that way saved me a lot of headaches when trying to use the
> openzfs packages (which don't work on 12.2). Had to eventually install
> via the ports tree.

Good to know. I'd expect something like this to be fixed soon, however?

> A bunch of sysctls are the same, a bunch are named slightly differently,
> and there's a whole bunch of new ones. Best bet is to comment then all
> out and see if the autotune setup works for you. If not, then tweak the
> new sysctls as you go.

I'm usually totally fine with autotune, with the only exception of
vfs.zfs.arc_min and vfs.zfs.arc_max... I'll dump them out once it starts
working.

> It's just zfs_enable in rc.conf for both base and port ZFS.

Cool.

> You can "zfs send" between versions without issue.

Double cool :)

> Can't help with the GELI or xattrs questions as I don't use those.

I guess GELI is a no-brainer, xattrs I guess I'll find out..

Best Regards and thanx a lot!!

Lorenzo