Manage Luns For Storage Area Networks; About Luns - NETGEAR ReadyDATA 5200 Software Manual

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Manage LUNs For Storage Area Networks

•

About LUNs

• Create a LUN
• View and Change the Properties of a LUN, Including Size Expansion
• Migrate a LUN to Another Volume
• Delete a LUN
About LUNs
Each LUN has a configuration that is independent of other LUNs that reside on the same
volume. A LUN configuration includes settings such as logbias, compression, deduplication
(referred to as dedupe), protection, file-sharing protocols, provisioning, LUN size, and access
rights. These settings are explained in the following sections.
The configuration settings of a LUN are stored in the volume (that is, in the pool) in which the
LUN resides. This design allows a LUN to be portable when a disk is moved from one array
to another array. However, iSCSI settings are not moved when you migrate a LUN from one
volume to another volume or when you move the disk or disks on which the volume with the
LUN resides to another array. (For information about how to configure the iSCSI settings, see
Manage Access Rights for LUN Groups
You can specify whether a snapshot is created, and with what frequency it is created.
You can specify the size of a LUN in two ways:
• Thin. Even though you specify the size of a thin LUN when you create it, storage space is
assigned on demand instead of up front. This method greatly improves the utilization rate
of the LUN because storage space is assigned only as data is written to the LUN.
However, the size of the LUN is reported as the total storage space that you specify when
you create the LUN. As data is written to the LUN, the used storage space is displayed on
the volume icon in purple.
A thin LUN lets you overallocate its size, that is, you can assign a LUN size that is larger
than the size of the volume. You can then expand the volume as needed (if necessary,
adding disks in the process) without expanding the size of the LUN, and therefore without
disconnecting users. Make sure that you watch the volume capacity of the volume on
which the overallocated LUN resides so you do not run out of storage space
unexpectedly.
Note: NETGEAR recommends that you do not use an overallocated LUN for
storage of critical data. Instead, use a thick LUN.
ReadyDATA OS 1.2
on page 107.)
Manage Shares and LUNs
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