HP XP P9500 Storage - Manual (Page 59)

Particularly in the following cases, the I/O load concentrated on specific components may decrease
performance during quick format operations.
•
In a configuration that satisfies both of these conditions, many quick format operations are
started at the same time.
◦ The following comprise the minimum configuration of a module: CHA (CHannel Adapter)
CPC (Cache Path Control adapter) DKA (DisK Adapter) ESW (PCI Express Path Switch)
◦ The number of modules is one or two.
•
In a configuration that satisfies either of these conditions, quick format operations are started.
If the number of CPCs, ESWs, DKAs, and CHAs is extremely unbalanced between modules
in a configuration composed of multiple modules.
For example, the configuration is unbalanced when many CPCs, ESWs, DKAs, and CHAs
are installed in one module and the least number of CPCs, ESWs, DKAs, and CHAs are
installed in another module.
◦
◦ If the number of CPCs, ESWs, DKAs, and CHAs in a module that connects to an ESW
(Basic) or a ESW (Option) is extremely unbalanced between an ESW (Basic) or an ESW
(Option).
For example, an ESW(Basic) in one module may be connected by many CPCs, ESWs,
DKAs, or CHAs and also connected by the least number of CPCs, ESWs, DKAs, or CHAs.
For configurations such as those described above, perform the quick format operation on one LDEV
first to confirm that the I/O performance of the host does not decrease. After that, it is strongly
recommended that the number of quick format operations you perform at the same time is increased
one by one.
For configurations other than those described above, it is recommended that no more than eight
quick format operations are started at the same time. After eight or fewer quick formats, it is
recommended that four quick format operations are started in each increment while I/O performance
is monitored on the host.
Quick Format specifications
Description Item
The internal volume must be in blocked status. However, you do not need to create a
system disk. Preparation for executing the
Quick Format feature
Up to 36 parity groups can concurrently undergo Quick Format. There is no limit on
the number of volumes that can undergo Quick Format. The number of parity groups
that can undergo Quick
Format
While one Quick Format operation is in progress, another Quick Format operation can
be performed. A maximum of 36 parity groups can concurrently undergo Quick Format. Concurrent Quick Format
operations
At the beginning of the Quick Format operation, Remote Web Console performs
preliminary processing to generate management information. If a volume is undergoing Preliminary processing
preliminary processing, the Remote Web Console main window shows the status of the
volume as Preparing Quick Format. While preliminary processing is in progress, hosts
cannot perform I/O access to the volume.
If a volume undergoing Quick Format is blocked, the storage system recognizes that
the volume is undergoing Quick Format. After the volume is restored, the status of the
volume changes to Normal (Quick Format). Blocking and restoring of
volumes
If all volumes in one or more parity groups undergoing Quick Format are blocked, the
displayed number of parity groups undergoing Quick Format decreases by the number
of blocked parity groups. However, the number of parity groups that have not undergone
and can undergo Quick Format does not increase. To calculate the number of parity
Formatting LDEVs 59