Multiterabyte UFS File Systems

Multiterabyte UFS file system support is available only for systems that run a 64-bit kernel. This feature is new in the Software Express pilot program and in the Solaris 9 8/03 release. This feature is included in the Solaris 10 3/05 release.

The Solaris 10 OS provides support for multiterabyte UFS file systems on systems that run a 64-bit Solaris kernel. Previously, UFS file systems were limited to approximately 1 terabyte (Tbyte) on both 64-bit systems and 32-bit systems. All UFS file system commands and utilities have been updated to support multiterabyte UFS file systems.

You can initially create a UFS file system that is less than one Tbyte. You can specify that the file system can eventually be grown to a multiterabyte file system by using the newfs -T command. This command sets the inode and fragment density to scale appropriately for a multiterabyte file system.

Support for a multiterabyte UFS file system assumes the availability of multiterabyte LUNs. These LUNS are provided as Solaris Volume Manager volumes, or as physical disks that are greater than one Tbyte.

Features of multiterabyte UFS file systems include the following:

• You can create a UFS file system to a maximum of 16 Tbytes in size.

• You can create a file system that is less than 16 Tbytes, which can later be increased in size to a maximum of 16 Tbytes.

• Multiterabyte file systems can be created on physical disks and on Solaris Volume Manager's logical volumes.

• UFS logging is enabled by default on file systems greater than 1 Tbyte. Multiterabyte file systems benefit from the performance improvements of having UFS logging enabled. Multiterabyte file systems also benefit from the availability of logging because the fsck command might not have to be run when logging is enabled.

Limitations of multiterabyte UFS file systems include the following:

• You cannot mount a file system that is greater than 1 Tbyte on a system that runs a 32-bit Solaris kernel.

• You cannot boot from a file system that is greater than 1 Tbyte on a system that runs a 64-bit Solaris kernel. This limitation means that you cannot put a root (/) file system on a multiterabyte file system.

• These systems do not support individual files greater than 1 Tbyte.

• The maximum number of files per Tbyte of UFS file system is 1 million. This limit is intended to reduce the time it takes to check the file system with the fsck command.

• The maximum quota that you can set on a multiterabyte UFS file system is 2 Tbytes of 1024–byte blocks.

• Using the fssnap command to create a snapshot of a multiterabyte UFS file system is not currently supported.

For more information, see “What’s New in File Systems in the Solaris 10 Release?” in the System Administration Guide: Devices and File Systems.