3PAR InForm® OS 2.3.1 CLI Administrator's Manual (320-200180 Rev B, February 2010)

10.7
Spare Chunklets
InForm OS Version 2.3.1 3PAR InForm CLI Administrator’s Manual
10.4 Spare Chunklets
Some chunklets are identified as spares when the storage server is first set up at installation.
Data from other chunklets is moved or reconstructed onto these spare chunklets in response to
a chunklet or disk failure or when a drive magazine needs to be serviced. This initial spare
storage totals the amount of storage in a single drive magazine, using the largest size physical
disks.
How spare chunklets work:
■ When a connection is lost to a physical disk or a physical disk fails, all future writes to the
disk are automatically written to a logging logical disk until the physical disk comes back
online or until the time limit for logging is reached. Logging disk space is allocated when
the storage server is set up.
■ If the time limit for logging is reached, or if the logging logical disk becomes full, relocation
of chunklets on the physical disk to other chunklets, free chunklets or allocated spares,
starts automatically. Free chunklets are chunklets that are not used by the system.
■ For automatic relocations, the system uses up a maximum of one disk worth of chunklets
per system node.
■ If the system uses up its free or spare chunklets for relocation, an alert is generated.
■ Once the spare and free chunklets are used up, automatic relocation no longer occurs. In
most cases, some data redundancy is lost. The system also generates an alert.
10.4.1 Viewing Spare Chunklets
Use the showspare command to display information about all spare chunklets. If a spare
chunklet is in use, the
showspare output includes the name and ID of the logical disk using it,
as well as the chunklet’s position on the logical disk. If the spare chunklet is not in use, it is
listed as
available, and the columns relating to the logical disk show only dashes.
NOTE: Local chunklets are chunklets on disks, which are used by the node that
owns the logical disk for the chunklet being relocated.