Migrating a UFS File System With Solaris Volume Manager Volumes Configured to a ZFS Root File System

You can migrate your UFS file system if your system has Solaris Volume Manager (SVM) volumes. To create a UFS boot environment from an existing SVM configuration, you create a new boot environment from your currently running system. Then create the ZFS boot environment from the new UFS boot environment.

Overview of Solaris Volume Manager (SVM). ZFS uses the concept of storage pools to manage physical storage. Historically, file systems were constructed on top of a single physical device. To address multiple devices and provide for data redundancy, the concept of a volume manager was introduced to provide the image of a single device. Thus, file systems would not have to be modified to take advantage of multiple devices. This design added another layer of complexity. This complexity ultimately prevented certain file system advances because the file system had no control over the physical placement of data on the virtualized volumes.

ZFS storage pools replace SVM. ZFS completely eliminates the volume management. Instead of forcing you to create virtualized volumes, ZFS aggregates devices into a storage pool. The storage pool describes such physical characteristics of storage device layout and data redundancy and acts as an arbitrary data store from which file systems can be created. File systems are no longer constrained to individual devices, enabling them to share space with all file systems in the pool. You no longer need to predetermine the size of a file system, as file systems grow automatically within the space allocated to the storage pool. When new storage is added, all file systems within the pool can immediately use the additional space without additional work. In many ways, the storage pool acts as a virtual memory system. When a memory DIMM is added to a system, the operating system doesn't force you to invoke some commands to configure the memory and assign it to individual processes. All processes on the system automatically use the additional memory.

Example 11–2 Migrating From a UFS root (/) File System With SVM Volumes to ZFS Root Pool

When migrating a system with SVM volumes, the SVM volumes are ignored. You can set up mirrors within the root pool as in the following example.

In this example, the lucreate command with the -m option creates a new boot environment from the currently running system. The disk slice c1t0d0s0 contains a UFS root (/) file system configured with SVM volumes. The zpool command creates a root pool, c1t0d0s0, and a RAID-1 volume (mirror), c2t0d0s0. In the second lucreate command, the -n option assigns the name to the boot environment to be created, new-zfsBE-name. The -p option specifies where to place the new boot environment, rpool.

# lucreate -n ufsBE -m /:/dev/md/dsk/d104:ufs
# zpool create rpool mirror c0t0d0s0 c0t1d0s0
# lucreate -n c0t0d0s0 -s ufsBE -p zpool

The boot environment, c0t0d0s0, is ready to be upgraded and activated.