HP StorageWorks SAN Virtualization Services Platform Best Practices Guide (5697-0935, May 2011)

physical disk A disk device that can be discovered and managed by VSM.
PiT Point-in-Time. A VSM term denoting an entity created by a snapshot that represents the freezing
of a virtual disk’s data at a particular time and the redirection of any further modifications to the
virtual disk’s data to a new virtual disk, called a temporary virtual disk.
POST Power-on Self Test. The diagnostic sequence executed by devices during system startup.
primary path For an active/active or active/passive device, a path belonging to the set of paths that are active
by default, as viewed by the server.
See also active/passive RAID, active path, and secondary path..
PSC Physical storage container. A path from a DPM to a back-end LU. There are eight PSCs between
any two DPM initiator ports and a back-end LU presented to the domain by an eight-port storage
array (for example, an HP EVA8100).
Q
quad A Data Path Module purpose-built ASIC that is capable of directing the data to and from the
hosts. The DPM has four quads, with all capable of communicating across all ports, although it
is desirable to keep traffic within a quad if possible. Each quad contains two front or host-facing
ports, and two back or storage ports. Each of these ports is capable of a 4 Gbit/s Fibre Channel
rate. Therefore, using additional quads may be necessary as a multiple of that 8 Gbit/s or 6.4
MB/s rate.
R
RPO Recovery Point Objective. The point in time to which you must recover data as defined by your
organization. This is generally a definition of what an organization determines is an acceptable
loss in a distressed situation.
RTO Recovery Time Objective. The duration of time and a service level within which a business process
must be restored after a disaster to avoid unacceptable consequences associated with a break
in business continuity.
S
SAN Storage Area Network. A network specifically dedicated to the task of transporting data between
storage systems and servers. SANs are traditionally connected over FC networks but have also
been built using iSCSI technology.
secondary path For an active/passive device, the set of paths that are passive by default.
See also active/passive RAID, passive path, and primary path..
setup virtual disk A virtual disk that contains the virtualized VSM configuration for the SVSP domain, including, for
example, information about storage pools and virtual disks defined on the domain.
SFP Small form-factor pluggable. The 2 Gbps or faster form factor of the removable optical transceiver
used by the Data Path Module, HBAs, and most Fibre Channel switches. It uses the LC-type
connector.
snapclone A VSM service that creates physical copies of VSM virtual disks without using host resources.
snapshot Either of the following:
• A VSM service that creates multiple low-capacity, read-write snapshots of virtual disks and
makes the snapshots available to any number of hosts, for purposes such as data recovery,
backup and testing, while the original virtual disk stays online and continues to be updated.
• A read-write entity that makes PiT data available to any host as a logical drive.
SNMP Simple Network Management Protocol. The protocol used by the Data Path Module to report
exception conditions to third-party network management applications.
SSH Secure Shell. A protocol and application for communicating with a remote computer system. SSH
is a more secure alternative to using telnet to communicate with the Data Path Module.
storage pool In VSM, a set of back-end LUs or stripe sets from which you can create virtual disks and allocate
them to hosts. SVSP storage pools enable you to classify storage elements into classes of service
and provide different classes of service to different hosts.
80 Glossary