Hpss User Storage Space; Hpss Infrastructure Storage Space - IBM High Performance Storage System HPSS Installation Manual

Starting with HPSS 6.2 there are many enhancements to the storage system to take advantage of
Storage Area Networks. Though separated in Figure 4, in reality there is usually only one SAN at an
installation and all the resources are attached to it. Besides the HPSS Movers being connected to
SAN, the end-user clients are often SAN attached as well. The result is that the data paths take
greater advantage of the SAN architecture and fewer store-and-forward operations are needed
through Movers (i.e. clients transfer data across SAN directly to disk resources, the mover just
manages the transfer) and less traffic across the TCP/IP network infrastructure. Adequately
provisioning the "data pipes" is still critical, but the equation has changed to rely more heavily on the
SAN to carry the data traffic.

3.5.1. HPSS User Storage Space

HPSS files are stored on the media that is defined and allocated to HPSS. Enough storage space must
be provided to meet the demands of the user environment. HPSS assists in the management of space
by providing SSM screens with information about total space and used space in all of the defined
storage classes. In addition, alarms can be generated automatically based on configurable threshold
values to indicate when space used in a given Storage Class has reached a threshold level. In a
hierarchy where data is being migrated from one hierarchy level to a lower one, management of space
in the Storage Class provided is done via the migration and purge policies that are provided. The
basic factors involved are the total amount of media space available in the Storage Class being
migrated and the rate at which this space is used. This will drive how the migration and purge
policies are set up for the Storage Class. For more details on this, see Section 3.9.1: Migration Policy
on page 94 and Section 3.9.2: Purge Policy on page 95. Failure to provide enough storage space to
satisfy a user request results in the user receiving a NO SPACE error. It is important to understand
that the Core Server writes files only to the top level of the COS hierarchy. If the top level does not
have sufficient free space for the write operation, it will fail, regardless of the amount of free space in
lower levels.

3.5.2. HPSS Infrastructure Storage Space

Figure 5: Basic HPSS Metadata and Filesystem Allocation represents what is typically needed to
support a basic HPSS server node configuration. Specific function and required space allocation for
the defined items will be discussed in following sections. For now, the diagram helps to define the
road map between raw, physical disks and the required filesystems and logical volumes/partitions to
operate an HPSS system.
HPSS Installation Guide July 2008
Release 6.2 (Revision 2.0) 69