Preparing Disks for ZFS Storage Pools

Creating ZFS storage pools in Oracle Solaris 11 is similar to creating pools in Oracle Solaris 10 . The following sections provide summary information about preparing disks for a ZFS root pool and non-root pools.

Review the following general pool device configuration recommendations:

• Create non-root pools by using whole disks, which are easier to manage than disk slices. For example, you can easily create a mirrored storage pool with 4 devices as follows:

  # zpool create tank mirror c0t1d0 c0t2d0 mirror c1t1d0 c1t2d0

• When ZFS storage pools are created with whole disks, the disks are labeled with an EFI label rather than an SMI label. You can identify an EFI label by the lack of cylinder information in the disk label as displayed in the format utility. For example:

  partition> print
  Current partition table (original):
  Total disk sectors available: 286478269 + 16384 (reserved sectors)
  
  Part      Tag    Flag     First Sector         Size         Last Sector
    0        usr    wm               256      136.60GB          286478302    
    1 unassigned    wm                 0           0               0    
    2 unassigned    wm                 0           0               0    
    3 unassigned    wm                 0           0               0    
    4 unassigned    wm                 0           0               0    
    5 unassigned    wm                 0           0               0    
    6 unassigned    wm                 0           0               0    
    8   reserved    wm         286478303        8.00MB          286494686    

• We recommend that you create non-root pools with whole disks but keep in mind that root pool disks need an SMI label from which to boot.

ZFS Root Pool Installation Improvements

Review the following installation improvements for root pools:

• Disk label improvements – If the disk label or labels that are intended to contain the OS are unknown or EFI, the disks will be automatically relabeled with an SMI label.

  In addition, the AI installer has improved the whole_disk keyword syntax so that if whole_disk is set to true, the disk's contents are replaced, even if it has existing partitions or slices.

• AI installation of a mirrored root pool – Oracle Solaris 10 installation features allow you to create a mirrored root pool during installation.

  You can use AI manifest keyword syntax to create a mirrored root pool during an Oracle Solaris 11 automatic installation. For example:

  <!DOCTYPE auto_install SYSTEM "file:///usr/share/install/ai.dtd.1">
  <auto_install>
    <ai_instance name="default">
      <target>
        <disk whole_disk="true" in_zpool="rpool" in_vdev="root_mirror">
          <disk_name name="c8t0d0" name_type="ctd"/>
        </disk>
        <disk whole_disk="true" in_zpool="rpool" in_vdev="root_mirror">
          <disk_name name="c8t1d0" name_type="ctd"/>
        </disk>
          <zpool name="rpool" is_root="true">
            <vdev name="root_mirror" redundancy="mirror"/>
            <be name="solaris"/>
          </zpool>
        </target>

  In the above example, the installer will automatically create slice 0 on each disk, c8t0d0 and c8t1d0, which will be used to create a mirrored root pool. In addition, because an SMI label is created on disks for the root pool, the installer will also create a slice 2 and a slice 8 on x86 systems.

ZFS Root Pool Device Requirements

In general, root pool devices are relabeled and the root pool is created when the system is installed. Be aware of the following device requirements if you create a mirrored root pool after installation by using the zpool attach command or if you replace a disk in a root pool.

• If you attach a root pool disk with the zpool attach command after the system is installed to create a mirrored root pool and the intended disk contains an EFI label, you will need to relabel the disk with an SMI label.

  In the Oracle Solaris 11 release, you can use the following shortcut command to force an SMI label to a disk with an EFI label that can be attached to an existing root pool. For example:

  # format -L vtoc -d c1t0d0
  Searching for disks...done
  selecting c1t0d0
  [disk formatted]
  c1t0d0 is labeled with VTOC successfully.

  Be very careful that you are relabeling the correct disk because this command does no error checking.

  If you force an SMI (VTOC) label on a disk that is intended for the root pool, the default partition table is applied. This means that the default s0 slice size might be too small. For more information about changing partition or slice sizes, see How to Label a Disk in Oracle Solaris Administration: Devices and File Systems.

  Boot blocks are applied automatically during a zpool attach operation of a root pool disk.

• If you use the zpool replace command to replace the root pool disk, you must first apply an SMI label and also apply the boot blocks. For more information, see How to Replace a Disk in a ZFS Root Pool in Oracle Solaris Administration: ZFS File Systems.

• The disk that is intended for the root pool must be less than 2 TBs in size so that the Oracle 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 an beadm operation, you will see a message similar to the following:

  ERROR: ZFS pool name does not support boot environments

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

For more information about creating ZFS root pools, see ZFS Storage Pool Creation Practices.