User's Manual

HP StorageWorks File System Extender Software user guide 99
Volumes of this type cannot be created on the supported LTO Ultrium media and are not used on disk
media.
FSE supports up to 255 volumes on disk media. Other specifics of different media types are described in
the next section.
FSE media types
The following is a list of the supported media types and their characteristics:
• LTO Ultrium 1, LTO Ultrium 2, LTO Ultrium 3
Used in regular and backup media pools.
LTO Ultrium media do not support multiple volumes and do not need to be formatted. A single data
volume is created on such media during initialization.
Media that belong to the backup FSE media pool should be configured with only one volume.
For details on backup media, see ”Backup media management” on page 223.
• LTO Ultrium 3 WORM
Used in WORM media pools only.
Once recorded, WORM media cannot be overwritten, re-formatted, or re-initialized, but new data can
be appended to the existing contents. Note that the FSE prevents WORM media from being initialized
in a non-WORM media pool.
• Disk media
Used in regular media pools only.
Disk media are implemented as storage space in a directory on the consolidated FSE system or FSE
server. This storage space must consist of multiple file systems, with one file system used for each disk
medium. Each file system is mounted to a separate subdirectory. On Linux platform, for example, two
disk media are represented as /var/opt/fse/dm/dm000001 and
/var/opt/fse/dm/dm000002. Instead of barcode, the last part of path (dm000001, dm000002) is
used for identification. You should use an appropriate naming convention which will prevent disk
media from being misidentified as tape media.
Linux specific
On Linux platform, disk media are located in the directory /var/opt/fse/dm.
Windows specific
On Windows platform, disk media are located in the directory %InstallPath%\var\dm.
The value of %InstallPath% depends on the choice made in the FSE installation process. It defaults
to C:\Program Files\Hewlett-Packard\FSE.
A file system for disk media can be either local or remote. For more information, see ”Disk media” on
page 99.
Disk media
An FSE disk medium is a mounted file system that emulates an FSE tape medium; therefore, managing disk
media is similar to managing tape media. Using FSE disk media is advantageous in terms of recall, since
it significantly decreases the time required to bring files back online (offline file access times).
When an FSE user requests an offline file, a recall job first attempts to allocate a medium from the FSE disk
media pool and only if no such medium exists it allocates a tape medium. When offline files are located
on a disk medium, recalls can run simultaneously and are not affected by the number of currently
unallocated drives, but by the corresponding FSE partition configuration parameters. No more than
MaxNumDrivesRecall x 2 jobs can be started at once. The MaxNumDrivesRecall and other
configurable FSE partition parameters are described in ”Partition allocation and job priority policy” on
page 144.
Before starting to use disk media, you should consider the following points about the two types of disk in
an FSE implementation:
Performance disk