User's Manual

hp StorageWorks File System Extender User Guide 87
• Data volume
Used to store regular migration data. Each FSE medium must have at least one data volume; usually, an
FSE medium is partitioned into several data volumes. LTO Ultrium media do not support multiple
medium volumes, and they do not need to be formatted. FSE supports up to 255 data volumes on disk
media.
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 1, LTO Ultrium 2, and LTO Ultrium 3 media do not support multiple volumes and do not
need to be formatted. A single data volume is created on such media during initialization.
If a medium is used as a backup medium, it must be configured with only one volume, and backup
media in such a pool should be formatted but not initialized. For details about backup media, see
”Backup media management” on page 175.
• Disk media
Used in regular media pools.
Disk media are implemented as a file system mounted to a subdirectory on the consolidated FSE
implementation or an FSE server. For example, two disk media are represented as
/var/opt/fse/dm/dm000001 and /var/opt/fse/dm/dm000002. The last part of a pathname
(dm000001, dm000002) is used as a ‘barcode’ for identification of disk media. This naming
convention prevents disk media interfering with real barcodes.
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 87.
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 are started at once. The MaxNumDrivesRecall and other
configurable FSE partition parameters are described in ”Partition allocation and job priority policy” on
page 128.
Before starting to use disk media, you should consider the following points about the two types of disk in
an FSE implementation:
Performance disk
Dedicate a disk with high performance for FSE software installation and HSM file systems. Such a disk
serves as a primary storage space of files with high frequency of user access, which may affect the
performance of the whole FSE implementation. A performance disk is not meant to be a secondary storage
space (file archive storage), thus its capacity is not as important as its high performance, which enables
optimal operation of FSE.
Capacity disk