This guide will show you how to set up znapzend
on OpenIndiana to backup a ZFS fileystem to a different ZFS filesystem. It should also work with other Illumos distributions.
Assumptions
- The backup destination ZFS zpool, e.g.
destinationzpool
, has already been created - The backup destination ZFS dataset, e.g.
destinationzpool/destinationzfsdataset
has already been created - Both of the above are on the same machine as the source dataset
See the Oracle Solaris docs for instructions on Steps 1 to 3. At that link, pick the latest Solaris release and search the ensuing page for "ZFS."
Step 1: Set up the pkgsrc repo
As of this writing, znapzend
does not exist in the OpenIndiana repos, so you'll have to set up the 3rd party pkgsrc repo that has it.
Step 2: Install znapzend
# pkgin install znapzend
Step 3: Configure znapzend
The official documentation is overly complicated for this purpose. A simple example config is:
znapzendzetup create --recursive SRC '1h=>15min,1d=>1h,1w=>1d,1m=>1w,1y=>1m' sourcezpool DST '1h=>15min,1d=>1h,1w=>1d,1m=>1w,1y=>1m' destinationzpool/destinationzfsdataset
Explaining the above command:
-
znapzendzetup
: Set upznapzend
-
create
: Generate a new backup config -
--recursive
: Backup all child datasets onsourcezpool
-
SRC
: Source zpool settings begin here -
'1h=>15min,1d=>1h,1w=>1d,1m=>1w,1y=>1m'
: For each comma-separated parameter, take a snapshot at interval equal to the value to the right of the arrow, and then destroy that snapshot after the value to the left of the arrow, e.g.1h=>15min
means take a snapshot every 15 minutes and destroy all such snapshots after they've existed for an hour. See official documentation for more options -
sourcezpool
: The zpool you want to backup -
DST
: Destination zpool & ZFS dataset settings begin here -
'1h=>15min,1d=>1h,1w=>1d,1m=>1w,1y=>1m'
: Same as before -
destinationzpool/destinationzfsdataset
: The destination zpool and ZFS dataset
Step 4: Check your znapzend config
# znapzend --noaction --debug
The output of the above command may appear to freeze and not return you to a prompt. If that happens just hit CTRL + C
until the prompt shows up again. As long as the output has no errors, your config should be good.
Step 5: Start znapzend in the background
# znapzend --daemonize
Step 6: Wait for the smallest interval set in Step 3
Step 7: Check that znapzend is creating snapshots as configured
# zfs list -t snapshot
You should see snapshots with %Y-%m-%d-%H%M%S
(znapzend
's default) timestamps in their names.
Step 8: Kill znapzend
There are many ways to do this, but I prefer using htop
(install it from the OI repos if you haven't already):
# htop
- Press
F4
to filter - Type
znapzend
- Use the arrow keys to highlight any matching entries
- Press
F9
while each matching entry is highlighted to kill it - Press
F10
to exit
Step 9: (Optional) Disable other snapshot utilities
CoW filesystems like ZFS sometimes have difficulty with a large number of snapshots combined with low space. Also, destroying snapshots is computationally expensive, and taking them too frequently can slow down the machine.
Therefore, it's a good idea to disable other snapshot utilities if they are likely to cause such issues. For example, if you use Time Slider:
- Open Time Slider
- Uncheck
Enable Time Slider
- Click
Delete Snapshots
- In the window that follows, click
Select All
- Click
Delete
The deletion process may take a very long time (I suggest running it overnight.) If any Time Slider snapshots remain after the bulk deletion, just run it again and that should take care of the rest.
Step 10: Generate a znapzend service manifest
Wouldn't it be nice if you could start znapzend
at boot? Unlike Linux and FreeBSD, OI's crontab syntax lacks an @reboot
option, so anything that starts with OS has to be a service. While @reboot
makes things simple, service creation has some advantages, such as alerting the user when a service isn't running as expected.
sudo svccfg export znapzend
Copy the output of that command to a text editor. You could also possibly use |
or echo
to combine this and the following manifest file creation steps.
BONUS: You can use svccfg export
combined with the following steps to turn just about any background executable into a service!
Step 11: Create the znapzend service manifest XML file
Create the following file /var/svc/manifest/site/znapzend.xml
using your preferred method, then copy the output of Step 10 to it and save the file.
I use:
# nano /var/svc/manifest/site/znapzend.xml
- Copy the output from Step 10 into
nano
- Press
CTRL + O
to save the file - Press
CTRL + X
to exit
Step 12: Validate the manifest file
# svccfg validate /var/svc/manifest/site/znapzend.xml
Step 13: Import the manifest file
# svccfg import /var/svc/manifest/site/znapzend.xml
Step 14: Start the znapzend service
# svcadm enable znapzend
And that's it. Now you have automatic, incremental, rotating, easily restored backups of your OS filesystem.
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