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How to setup znapzend with local backup on OpenIndiana

jdrch profile image jdrch ・4 min read

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

  1. The backup destination ZFS zpool, e.g. destinationzpool, has already been created
  2. The backup destination ZFS dataset, e.g. destinationzpool/destinationzfsdataset has already been created
  3. 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
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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
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Explaining the above command:

  • znapzendzetup: Set up znapzend
  • create: Generate a new backup config
  • --recursive: Backup all child datasets on sourcezpool
  • 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
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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
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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
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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
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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
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  • 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
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Step 13: Import the manifest file

# svccfg import /var/svc/manifest/site/znapzend.xml
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Step 14: Start the znapzend service

# svcadm enable znapzend
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And that's it. Now you have automatic, incremental, rotating, easily restored backups of your OS filesystem.

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