How Can I Access Old Boot Snapshots?

[NASbox]

I am running FreeNAS 11.1-U7, and for some reason my FreeNAS would not boot (likely do to an earlier update) and I had to reinstall and restore the config.

This caused a bit of a probem because I had some customization in /root that I want to recover.

AFAIK /root lives in freenas-boot/ROOT/11.1-U7-Please correct me if I am wrong.

If that is the case, the files I want are in this snapshot:

Code:

freenas# zfs list -t snap -r freenas-boot/ROOT/11.1-U7
NAME                                            USED  AVAIL  REFER  MOUNTPOINT
[SNIP]
freenas-boot/ROOT/11.1-U7@2019-01-29-15:38:10  1.04G      -  1.04G  -

For ease of working I would like to just create /TMPMOUNT and mount the snapshot ReadOnly to this mount point. Can someone tell me how to do this without messing things up.

Thanks.

Just in case I need to look somewhere else, here are the datasets on the boot drive.

Code:

freenas-boot                                                   10.7G  96.8G   176K  none
freenas-boot/.system                                            180M  96.8G  4.34M  legacy
freenas-boot/.system/configs-66c5ca0d9b594eb08a0e7191ec86e4a6  73.6M  96.8G  73.6M  legacy
freenas-boot/.system/configs-9d613bc4d69d4caa9ab03b2439285b53   136K  96.8G   136K  legacy
freenas-boot/.system/cores                                     16.8M  96.8G  16.8M  legacy
freenas-boot/.system/rrd-66c5ca0d9b594eb08a0e7191ec86e4a6      31.1M  96.8G  31.1M  legacy
freenas-boot/.system/rrd-9d613bc4d69d4caa9ab03b2439285b53      3.85M  96.8G  3.85M  legacy
freenas-boot/.system/samba4                                     468K  96.8G   468K  legacy
freenas-boot/.system/syslog-66c5ca0d9b594eb08a0e7191ec86e4a6   49.5M  96.8G  49.5M  legacy
freenas-boot/.system/syslog-9d613bc4d69d4caa9ab03b2439285b53    296K  96.8G   296K  legacy
freenas-boot/CUSTOM                                             163M  96.8G  78.4M  /CUSTOM
freenas-boot/ROOT                                              10.3G  96.8G   136K  none
freenas-boot/ROOT/11.0-U3                                       232K  96.8G   970M  /
freenas-boot/ROOT/11.0-U4                                       248K  96.8G   973M  /
freenas-boot/ROOT/11.1-RELEASE                                  424K  96.8G  1.08G  /
freenas-boot/ROOT/11.1-U4                                       452K  96.8G  1.09G  /
freenas-boot/ROOT/11.1-U5                                       452K  96.8G  1.10G  /
freenas-boot/ROOT/11.1-U6                                       572K  96.8G  1.10G  /
freenas-boot/ROOT/11.1-U6.3                                     440K  96.8G  1.04G  /
freenas-boot/ROOT/11.1-U7                                      9.32G  96.8G  1.07G  /
freenas-boot/ROOT/Initial-Install                                 8K  96.8G   980M  legacy
freenas-boot/ROOT/default                                       232K  96.8G   980M  legacy
freenas-boot/ROOT/default-20190917-081209                      1018M  96.8G  1018M  legacy
freenas-boot/grub                                              7.94M  96.8G  7.94M  legacy

 

[droeders]

You can use 'zfs clone' to duplicate/mount a snapshot to a new dataset. The FreeBSD man page for 'zfs' has this:

Code:

The following command creates a writable file system whose initial con-
tents are the same as pool/home/bob@yesterday.

   # zfs clone pool/home/bob@yesterday pool/clone

This article shows example usage as well:
https://www.howtoforge.com/tutorial/how-to-use-snapshots-clones-and-replication-in-zfs-on-linux/

Keep in mind that you'll need to destroy your cloned dataset after use, or the snapshot it's based on cannot be destroyed.

 

[NASbox]

You can use 'zfs clone' to duplicate/mount a snapshot to a new dataset. The FreeBSD man page for 'zfs' has this:

Code:

The following command creates a writable file system whose initial con-
tents are the same as pool/home/bob@yesterday.

   # zfs clone pool/home/bob@yesterday pool/clone

This article shows example usage as well:
https://www.howtoforge.com/tutorial/how-to-use-snapshots-clones-and-replication-in-zfs-on-linux/

Keep in mind that you'll need to destroy your cloned dataset after use, or the snapshot it's based on cannot be destroyed.

Thanks @droeders ... I created a clone with:
zfs clone freenas-boot/ROOT/11.1-U7@2019-01-29-15:38:10 freenas-boot/TEMPCLONE
Now, how do I mount it?

zfs list shows no mountpoint

Code:

freenas-boot/TEMPCLONE                                            8K  96.8G  1.04G  none

Edit:
I found a work around by doing:
zfs set -o mountpoint=/TEMPCLONE freenas-boot/TEMPCLONE
This mounted the clone at /TEMPCLONE and I was able to copy the files I needed.
I did a zfs destroy freenas-boot/TEMPCLONE and then rmdir /TEMPCLONE to clean up when I was done

For the benefit of others maybe someone could complete the following:

How should this statement be coded so it would mount then created snapshot?
zfs clone freenas-boot/ROOT/11.1-U7@2019-01-29-15:38:10 freenas-boot/TEMPCLONE
would
zfs clone -o mountpoint=/TEMPCLONE freenas-boot/ROOT/11.1-U7@2019-01-29-15:38:10 freenas-boot/TEMPCLONE
work?

ALSO

Is it necessary to clone the snapshot, or is it possible to simply mount the existing snapshot? (ReadOnly!)

What would happen if I did:
zfs set -o mountpoint=/TEMPMPUNT freenas-boot/ROOT/11.1-U7@2019-01-29-15:38:10
Would that mount the snapshot?
Would this screw anything up?
Would the snapshot be Readonly, or could it be damaged by overwriting?

Assuming the above worked, how would I "unset" the mountpoint option back to "not mounted" the way it was originally?