Hitachi 9900 V Series Chapter 1 Overview of LUN Expansion and Virtual LVI/LUN

PRELIMINARY RELEASE

Hitachi Lightning 9900™ V Series LUN Expansion and Virtual LVI/LUN User’s Guide 1

Chapter 1 Overview of LUN Expansion and Virtual LVI/LUN

LUSE operations allow hosts that can only use a limited amount of LUs per fibre interface to

have access to larger amounts of data using expanded LUs. LUSE operations include the

following:

 Creating new expanded LUs (LUSE volumes) (see section 3.2).

 Releasing expanded LUs (LUSE volumes) to individual LUs (see section 3.2.2).

 Changing the size of a LUSE volume (see section 3.2.3).

The following guidelines apply to LUN Expansion:

 A maximum of 256 expanded LUs can be configured on the same port.

 LDEVs that are to be combined into LUSE volumes must have no assigned SCSI paths and

be unmounted from the host. These are known as free (or available) LDEVs. For

instructions on deleting SCSI paths, please see Hitachi Freedom Storage™ Lightning

9900™ LUN Manager User’s Guide (MK-92RD105).

 Combining non-sequential LDEVs into a LUSE is supported, provided they are on the same

CU.

 Combining Virtual LVI/LUN volumes into a LUSE is supported, provided they are the same

size and emulation type and on the same CU. The order of operations is important: you

must first create one or more Virtual LVI/LUN volumes, and then combine those volumes

into a LUSE volume. You cannot perform Virtual LVI/LUN operations on an existing LUSE

volume because a LUSE volume must have a SCSI path already specified.

 Combining Virtual LVI/LUN volumes and normal volumes into the same LUSE is not

supported.

 Combining command devices, Just In Time and CruiseControl volumes into a LUSE is not

supported.

 Combining RAID 1 and RAID 5 into the same LUSE is not supported.

 Combining emulation types (OPEN-3, OPEN-8, OPEN-9, OPEN-E, or OPEN-L) into the same

LUSE is not supported.

 Some operating systems may experience slow disk access times with large logical units,

if they contain a large number of high usage files.

 The size of a LUSE can affect the amount of time required to perform backups.

Note: The queue depth for open systems can vary, depending on the type of platform. Please

contact your Hitachi Data Systems Customer Support Center for assistance.

Warning: Except for systems running Windows NT® or Windows® 2000, creating and releasing

expanded LUs is a destructive process. Be sure to back up your data before proceeding.