ZFS: Send and Receive

ZFS: Send and Receive

ZFS gives us the ability to move data with ZFS send and receive.  This can be used to combine snapshots, create full or incremental backups, or replicate data between servers on your LAN or even over the WAN.

Local Backup with Send

This is very simple, simply perform a send of a snapshot then output it to the file, I have complicated it a bit to include a folder which is named off of the current date (as would be helpful with backups).

# zfs send tank/filesystem@now > /backup/`date +%m%d%Y`/tank-filesystem.zsnd

Keep in mind zfs send only makes the backups.  In order to restore them we will need to be familiar with zfs receive as well.

Local Restore with Receive

With the basic restore it is very easy, simply specify the file system to restore to, and then define the file to pull it from.

# zfs receive tank/restoredfilesystem < /backup/03152013/tank-filesystem.zsnd

Notice here we are doing redirection back into the ZFS receive command from the file, also important to note that

Local Copy of a File System – Full Clone

Occasionally you may have the need to perform a full copy clone.  With a normal zfs clone you will end up with a zero copy clone (copy-on-write), you will also have additional dependency when using zfs clones, which require a little extra caution.  If using zfs send and receive to make a copy, then there is no interdependency.

# zfs send tank/originalfilesystem@now | zfs receive tank/copyfilesystem

Here we are able to structure the command with  just a simple pipe to separate the send and receive statements.

Local Compressed Backup with Send

Perhaps you want to store your backups in a compressed form.  All we need to do is insert a gzip into the mix.

# zfs send tank/test@now | gzip > /backup/`date +%m%d%Y`/tank-originalfilesystem.zsnd.gz

This method combines a pipe with a redirect, and will give us a compressed file.

Local Compressed Restore with Receive

Of course backups don’t do any good for us if we cannot restore them.

# gunzip -c -d /backup/03152013/tank-originalfilesystem.zsnd.gz | zfs receive tank/copyfilesystem

Here we unzip the file, and pipe that into the zfs receive statement.

Local Encrypted (and Compressed) Backup with Send

Some workloads have serious security requirements.  This will encrypt and compress the contents of the file system into a backup file.  In this example I am using encrypt/decrypt to perform the encryption with aes, I also was unable to get the piping and redirection working without also injecting gzip as well.

# zfs send tank/test@now | encrypt -a aes | gzip > /backup/`date +%m%d%Y`/tank-originalfilesystem.zsnd.aes.gz
Enter passphrase:
Re-enter passphrase:

Since we aren’t using any keys with encrypt it will prompt us for a passphrase.  Remember when using encryption your data becomes worthless if you do not

Local Encrypted (and Compressed) Restore with Receive

Decrypting and restoring the backup file is pretty straight forward, unzip the file, pipe it through decrypt and pipe it into zfs.

# gunzip -c -d /backup/03152013/tank-originalfilesystem.zsnd.aes.gz | decrypt -a aes | zfs receive tank/copyfilesystem
Enter passphrase:

Use the passphrase that you used when encrypting the backup to decrypt it.

Remote Copy of a File System – Full Clone

Sometimes a full clone is needed from one server to another, perhaps for data migration.

# zfs send tank/originalfilesystem@now | ssh root@192.168.1.21 "zfs receive tank/copyfilesystem"

One thought on “ZFS: Send and Receive

  1. matthew.mattoon Post author

    I removed my remote backup and remote restore procedure, as they were not working properly. I will add them back when I get them ironed out.