HP StorageWorks Scalable File Share System Installation and Upgrade Guide Version 2.2

Configuring the storage5–20
5.3.2 LUN roles
The primary purpose of the storage arrays is to store the Lustre file system data. However, the HP SFS system
also uses some storage to manage the system. When you configure the system, you use LUNs for each of
these different purposes, as follows:
MDS LUN
MDS LUNs are used to store the meta-data for a Lustre file system. In HP SFS systems, you
must create two MDS LUNs for each file system. The MDS LUNs are automatically created
on the arrays that are connected to the MDS and administration servers when those arrays
are configured.
In the HP SFS user interface, an MDS LUN is identified as an mds LUN.
See Section 5.5 for information on sizing the MDS LUN.
OST LUN
OST LUNs are used to store object data (that is, file contents) for a Lustre file system.
In the HP SFS user interface, an OST LUN is identified as an ost LUN.
Administration LUN
The administration LUN is used to store configuration information for the HP SFS system. Only
one administration LUN is used in the system; it is automatically created on one of the arrays that
are connected to the administration and MDS servers when those arrays are configured.
In the HP SFS user interface, the administration LUN is identified as the adm LUN.
Service LUN
Service LUNs are used to store management data and control data for the attached servers.
One service LUN is used for each server pair; it is automatically created on one of the arrays
attached to the server pair when the SFS20 arrays are configured. In the HP SFS user interface,
a service LUN is identified as a service LUN.
Spare Administration LUN
In systems using SFS20 storage, a spare administration LUN is created in case the original
administration LUN becomes unavailable because of complete failure of an SFS20 storage
array. In such a case, the system can be reconfigured to use the spare administration LUN
instead of the original administration LUN. All SFS20 storage arrays connected to the
administration and MDS servers have either an administration LUN or a spare administration
LUN.
In the HP SFS user interface, the spare administration LUN is identified as the admspare LUN.
Spare Service LUN
In systems using SFS20 storage, a spare service LUN is created in case the original service LUN
becomes unavailable because of complete failure of an SFS20 storage array. In such a case, the
system can be reconfigured to use a spare service LUN instead of the original service LUN. All
SFS20 storage arrays have either a service LUN or a spare service LUN.
In the HP SFS user interface, the spare administration LUN is identified as the svcspare LUN.