Managing ZFS Root Pool Components (Overview)

ZFS is the default root file system in the Oracle Solaris 11 release. Review the following considerations when installing the Oracle Solaris release.

• Installation – In the Oracle Solaris 11 release, you can install and boot from a ZFS root file system in the following ways:

  • Live CD (x86 only) – Installs a ZFS root pool on a single disk. You can use the fdisk partition menu during the installation to partition the disk for your environment.

  • Text installation (SPARC and x86) – Installs a ZFS root pool on a single disk from media or over the network. You can use the fdisk partition menu during the installation to partition the disk for your environment.

  • Automated Installer (AI) (SPARC and x86) – Automatically installs a ZFS root pool. You can use an AI manifest to determine the disk and the disk partitions to be used for the ZFS root pool.

• Swap and dump devices – Automatically created on ZFS volumes in the ZFS root pool by all of the above installation methods. For more information about managing ZFS swap and dump devices, see Managing Your ZFS Swap and Dump Devices.

• Mirrored root pool configuration – You can configure a mirrored root pool during an automatic installation. For more information about configuring a mirrored root pool after an installation, see How to Configure a Mirrored Root Pool.

• Root pool space management – After the system is installed, consider setting a quota on the ZFS root file system to prevent the root file system from filling up. Currently, no ZFS root pool space is reserved as a safety net for a full file system. For example, if you have a 68-GB disk for the root pool, consider setting a 67–GB quota on the ZFS root file system, which allows 1 GB of remaining file system space.

ZFS Root Pool Requirements

Review the following sections that describe ZFS root pool space and configuration requirements.

ZFS Root Pool Space Requirements

When a system is installed, the size of the swap volume and the dump volume are dependent upon the amount of physical memory. The minimum amount of pool space for a bootable ZFS root file system depends upon the amount of physical memory, the disk space available, and the number of boot environments (BEs) to be created.

Review the following ZFS storage pool space requirements:

• For a description of memory requirements for the different installation methods, see Oracle Solaris 11 Release Notes.

• At least 7-13 GB of disk space is recommended. The space is consumed as follows:

  • Swap area and dump device – The default sizes of the swap and dump volumes that are created by the Solaris installation programs vary based on the on the amount of memory on the system and other variables. Consider that the swap device size is generally 1/4 of physical memory and the dump device size is approximately half the size of physical memory.

    You can adjust the sizes of your swap and dump volumes to sizes of your choosing as long as the new sizes support system operation, during or after installation. For more information, see Adjusting the Sizes of Your ZFS Swap and Dump Devices.

  • Boot environment (BE) – A ZFS BE is approximately 4-6 GB. Each ZFS BE that is cloned from another ZFS BE doesn't need additional disk space. Consider that BE size will increase when the BE is updated, depending on the updates. All ZFS BEs in the same root pool use the same swap and dump devices.

  • Oracle Solaris OS Components – All subdirectories of the root file system that are part of the OS image, with the exception of /var, must be in the root file system. In addition, all Solaris OS components must reside in the root pool with the exception of the swap and dump devices.

ZFS Root Pool Configuration Requirements

Review the following ZFS storage pool configuration requirements:

• The disk that is intended for the root pool must have an SMI (VTOC) label.

• The disk that is intended for the root pool must be less than 2 TBs in size so that the Solaris OS can boot successfully.

• The pool must exist either on a disk slice or on disk slices that are mirrored. If you attempt to use an unsupported pool configuration during a beadm operation, you will see a message similar to the following:

  ERROR: ZFS pool name does not support boot environments

  For a detailed description of supported ZFS root pool configurations, see Creating a ZFS Root Pool.

• On an x86 based system, the disk must contain a Solaris fdisk partition. A Solaris fdisk partition is created automatically when the x86 based system is installed. For more information about Solaris fdisk partitions, see Guidelines for Creating an fdisk Partition in Oracle Solaris Administration: Devices and File Systems.

• Pool properties or file system properties can be set on a root pool during an automatic installation. The gzip compression algorithm is not supported on root pools.

• Do not rename the root pool after it is created by an initial installation. Renaming the root pool might cause an unbootable system.

Troubleshooting ZFS Root Pool Installation Problems

Review the following issues if you attempt to install the Oracle Solaris 11 release.

• Root pool disk is too small - If the disk slice that is intended for the root pool is too small, you might need to exit the installer, expand the size of the disk slice by using the format utility, and restart the installation. For example, during an automatic installation, you might see a message similar to the following on the system console:

  15:43:54    Space required for installation: 5.00gb
  15:43:54    Total available space: 4.55gb
  15:43:54    Error occurred during execution of 'target-selection' checkpoint.
  15:43:54    Failed Checkpoints:
  15:43:54    
  15:43:54        target-selection
  15:43:54    
  15:43:54    Checkpoint execution error:
  15:43:54    
  15:43:54        Error determining swap/dump requirements.
  15:43:54    
  15:43:54    Automated Installation Failed.  See install log at 
  /system/volatile/install_log

  • For information about expanding the root pool disk slice, see How to Create a Disk Slice for a ZFS Root File System in Oracle Solaris Administration: Devices and File Systems or How to Create a Disk Slice for a ZFS Root File System in Oracle Solaris Administration: Devices and File Systems.

  • After the root pool disk slice is expanded, restart the auto installer:

    # svcadm clear auto-installer

    Press return. You can observe the installation by using this command:

    # tail -f /system/volatile/install_log

  • Installation hangs - If the installation hangs and the root pool disk is small, such as 16 GB, and the system memory is large, such as 32 GB, then the disk is too small to create a swap volume and a dump volume. On a large memory system, the root pool disk must be large enough to contain the BE, the swap volume, and a dump device that is 1/2 to 3/4 the size of physical memory.