Managing ZFS Swap and Dump Devices

The installation process automatically creates a swap area and a dump device on a ZFS volume in the ZFS root pool.

The dump device is used when the directory where crash dumps are saved has insufficient space, or if you ran the dumpadm -n command syntax. The -n modifies the dump configuration to not run savecore automatically running after a system reboot.

Certain systems avail of the deferred dump feature in the current Oracle Solaris release. With this feature, a system dump is preserved in memory across a system reboot to enable you to analyze the crash dump after the system reboots. For more information, see About Devices and the Oracle Hardware Management Pack in Managing Devices in Oracle Solaris 11.4.

You can configure a shared swap and dump volume on which to manage both swap and dump data. When you configure a shared swap and dump volume, you can no longer take a live dump.

When your system has a shared swap and dump volume, the swap data is encrypted by default. However, to encrypt the dump data, you must configure the volume for encryption explicitly and provide the encryption keys.

Note the following guidelines when managing swap and dump volumes:

  • Starting with Oracle Solaris 11.4 SRU 60, the swap and dump devices are identified by the swap and dump properties on the ZFS volume. These devices are no longer listed in /etc/vfstab as they were in prior releases.

  • During an Oracle Solaris installation, a dump device is automatically created in the root pool, which is the recommended location for dump and swap devices. If the root pool is too small for the dump device, it can be relocated to a non-root pool. The non-root pool must be either a single-disk pool, a mirrored pool, or a striped pool. Dump devices are not supported on a RAIDZ pool.

  • Swap data is always encrypted with an ephemeral key when written to ZFS volumes.

  • Sparse volumes are not supported for swap volumes.

  • Using a swap file on a ZFS file system is not supported.