case-sensitive, single-fork file system.
a logical unit number is an address for an individual disk drive and by extension, the disk device itself
Xsan supports volume sizes of up to 2 petabytes (PB) and billions of files per volume
You can set up storage pools that have different performance or recoverability characteristics and assign folders to them using affinities. Users can then select where to store files based on their need for speed or safety.
having multiple storage pools per volume
having multiple LUNs per RAID controller
expanding a volume by adding LUNs to a storage pool
expanding a volume by adding storage pools to the volume
Using Xsan administration tools, you can pool LUNs with identical size, performance, and data protection properties
Affinities allow you to allocate different classes of storage to different purposes, without forcing users to adhere to annoying rules. Using Xsan administration tools, you can set up an affinity between a folder and a specific storage pool, so that files in the folder are stored only on that pool. Seamless to the end user, affinities ensure that an application or task that requires speed or extra protection always stores its files in a suitably fast or protected pool.
If, for example, you set up storage pools with different balances of performance and data redundancy, users can choose between faster and safer storage by putting files in the appropriate folder.
LDAP integration also makes it easy to manage disk space quotas. You can assign quotas to users, groups, applications, or any combination of the three. Xsan enforces two types of quotas for each user, group, or application:
Soft quota. The soft quota is the maximum space a user or group is expected to occupy on a regular basis. Users can exceed their soft quota, for a specified grace period only, up to their hard quota.
Hard quota. The hard quota is an absolute limit on the space a user or group can occupy. Users are prevented from using more space than specified by their hard quota.
Users or groups can exceed their soft quota provided that they drop below it at some point during the grace period you specify. If users or groups exceed their soft quota for longer than the grace period, the soft quota changes to a hard quota; they will
not be able to save additional data on the volume until they delete old files and drop below the soft quota.
Because Xsan is simply another file system, it adheres to the file system permissions built into Mac OS X, including permissions established in a central LDAP directory. Whether you use Open Directory, Active Directory, or another enterprise LDAP service,
Xsan accesses information in the directory accounts that you have in placemaking it easy to share permissions across computers.
You can use Xsan administration tools to set user and group permissions, as well as
access privileges, at several levels:
Restrict user access to folders on a volume by specifying owner, group, and general
Unmount a SAN volume from selected client computers.
Restrict a client computer to read-only access to a volume.
Remove a client from a SAN.
Block Allocation Size:
The allocation strategy you choose for a volume determines the order in which its storage pools are filled with data. You can choose round robin, fill, or balance.
If you choose round robin, Xsan writes new data in turn to each storage pool in the volume.
If you choose fill, Xsan writes all new data to the first storage pool in the volume until that storage pool is full, and then moves to the next storage pool. This is a good choice if you want to keep a particular storage pool unused as long as possible.
If you choose balance, Xsan writes new data to the storage pool with the most free space.
In heterogeneous computing environments, you can add nonMac OS X clients to your Xsan network using ADICs StorNext File System. Computers running StorNext File System on Windows XP, Windows 2003, Windows NT, Windows 2000, Linux, IRIX, Solaris, and AIX can access Xsan volumes directly over high-speed Fibre Channelwithout any modification. In addition, Mac and Xserve clients with Xsan can be added to an existing ADIC-based SAN environment.
ADICs StorNext Management Suite now supports Xsan deployments. This policy-based information lifecycle management (ILM) solution can be used in conjunction with ADICs Scalar line of tape libraries, offering a robust tape backup option for your Xsan volumes.