Xsan
Encyclopedia
Xsan is Apple Inc.'s storage area network (SAN)
or clustered file system for Mac OS X
. Xsan enables multiple Mac desktop and Xserve
systems to access shared block storage over a Fibre Channel
network. With the Xsan file system installed, these computers can read and write to the same storage volume at the same time. Xsan is a complete SAN solution that includes the metadata controller
software, the file system client software, and integrated setup, management and monitoring tools.
Xsan has all the normal features to be expected in an enterprise shared disk file system, including support for large files and file systems, multiple mounted file systems, meta data controller failover for fault tolerance, support for multiple operating systems, etc.
. The StorNext File System
and the Xsan file system share the same file system layout and the same protocol when talking to the meta data server. They also seem to share a common code base or very close development based on the new features developed for both file systems.
The Xsan website claims complete interoperability
with the Quantum Corporation StorNext File System
: "And because Xsan is completely interoperable with Quantum’s StorNext File System, you can even provide clients on Windows, Linux, and other UNIX platforms with direct Fibre Channel block-level access to the data in your Xsan-managed storage pool."
Quantum Corporation claims
"Complete interoperability with Apple’s Xsan and Promise RAID and Allows Xsan and Xserve RAID to support AIX, HP-UX, IRIX, Red Hat Linux, SuSE Linux, Mac OS X, Solaris, and Windows clients, including support for 64 Bit Windows and Windows Vista."
All the command line tools for Xsan begin with the letters cv, which stand for CentraVision - the original name for the file system.
The file system supports dynamic expansion and distribution of both data and metadata areas.
On 4 January 2005, Apple announced shipping of Xsan.
In May 2006, Apple released Xsan 1.2 with support for volume sizes of nearly 2 petabyte
s.
On 7 August 2006, Apple announced Xsan 1.4, which is available for Intel-based Macintosh computers as a Universal binary
and supports file system
access control list
s.
On 5 December 2006, Apple released Xsan 1.4.1.
On 18 October 2007, Apple released Xsan 1.4.2, which resolves several reliability and compatibility issues.
On 19 February 2008, Apple released Xsan 2, the first major update, which introduces MultiSAN, and completely redesigned administration tools. 2.1 was introduced on June 10, 2008. 2.1.1 was introduced on October 15, 2008. 2.2 was released September 14, 2009.
On 25 August 2011, Apple released Xsan 2.2.2, which brought along several reliability fixes.
Storage area network
A storage area network is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices...
or clustered file system for Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
. Xsan enables multiple Mac desktop and Xserve
Xserve
Xserve was a line of rack unit computers designed by Apple Inc. for use as servers. When the Xserve was introduced in 2002, it was Apple's first designated server hardware design since the Apple Network Server in 1996...
systems to access shared block storage over a Fibre Channel
Fibre Channel
Fibre Channel, or FC, is a gigabit-speed network technology primarily used for storage networking. Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards , an American National Standards Institute –accredited standards...
network. With the Xsan file system installed, these computers can read and write to the same storage volume at the same time. Xsan is a complete SAN solution that includes the metadata controller
Metadata controller
Metadata controller is a storage area network technology for managing file locking, space allocation and data access authorization.This is needed when several clients are given block level access to the same disk volume....
software, the file system client software, and integrated setup, management and monitoring tools.
Xsan has all the normal features to be expected in an enterprise shared disk file system, including support for large files and file systems, multiple mounted file systems, meta data controller failover for fault tolerance, support for multiple operating systems, etc.
Interoperability
Xsan is based on the StorNext File SystemStorNext File System
StorNext File System is a shared disk file system made by Quantum Corporation. It is installed on hosts that are connected to the same disk array in a storage area network . Client systems are not required to run the same operating system to access a shared filesystem containing StorNext data...
. The StorNext File System
StorNext File System
StorNext File System is a shared disk file system made by Quantum Corporation. It is installed on hosts that are connected to the same disk array in a storage area network . Client systems are not required to run the same operating system to access a shared filesystem containing StorNext data...
and the Xsan file system share the same file system layout and the same protocol when talking to the meta data server. They also seem to share a common code base or very close development based on the new features developed for both file systems.
The Xsan website claims complete interoperability
Interoperability
Interoperability is a property referring to the ability of diverse systems and organizations to work together . The term is often used in a technical systems engineering sense, or alternatively in a broad sense, taking into account social, political, and organizational factors that impact system to...
with the Quantum Corporation StorNext File System
StorNext File System
StorNext File System is a shared disk file system made by Quantum Corporation. It is installed on hosts that are connected to the same disk array in a storage area network . Client systems are not required to run the same operating system to access a shared filesystem containing StorNext data...
: "And because Xsan is completely interoperable with Quantum’s StorNext File System, you can even provide clients on Windows, Linux, and other UNIX platforms with direct Fibre Channel block-level access to the data in your Xsan-managed storage pool."
Quantum Corporation claims
"Complete interoperability with Apple’s Xsan and Promise RAID and Allows Xsan and Xserve RAID to support AIX, HP-UX, IRIX, Red Hat Linux, SuSE Linux, Mac OS X, Solaris, and Windows clients, including support for 64 Bit Windows and Windows Vista."
All the command line tools for Xsan begin with the letters cv, which stand for CentraVision - the original name for the file system.
Data representation
Xsan file system uses several logical storages to distribute information. The two main classes of information appear on Xsan: the user data (such as files) and the file system metadata (such as folders, file names, file allocaton information and so on). Most configurations use different storages for data and metadata.The file system supports dynamic expansion and distribution of both data and metadata areas.
History
In May 2006, Apple released Xsan 1.2 with support for volume sizes of nearly 2 petabyte
Petabyte
A petabyte is a unit of information equal to one quadrillion bytes, or 1000 terabytes. The unit symbol for the petabyte is PB...
s.
On 7 August 2006, Apple announced Xsan 1.4, which is available for Intel-based Macintosh computers as a Universal binary
Universal binary
A universal binary is, in Apple parlance, an executable file or application bundle that runs natively on either PowerPC or Intel-manufactured IA-32 or Intel 64-based Macintosh computers; it is an implementation of the concept more generally known as a fat binary.With the release of Mac OS X Snow...
and supports file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
access control list
Access control list
An access control list , with respect to a computer file system, is a list of permissions attached to an object. An ACL specifies which users or system processes are granted access to objects, as well as what operations are allowed on given objects. Each entry in a typical ACL specifies a subject...
s.
On 5 December 2006, Apple released Xsan 1.4.1.
On 18 October 2007, Apple released Xsan 1.4.2, which resolves several reliability and compatibility issues.
On 19 February 2008, Apple released Xsan 2, the first major update, which introduces MultiSAN, and completely redesigned administration tools. 2.1 was introduced on June 10, 2008. 2.1.1 was introduced on October 15, 2008. 2.2 was released September 14, 2009.
On 25 August 2011, Apple released Xsan 2.2.2, which brought along several reliability fixes.