IBM N Series, Hardware Manual

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IBM System Storage N series Hardware Guide
Host Utilities sets registry values to optimize performance that are based on your selections
during installation, including Windows MPIO, Data ONTAP DSM, or the use of Fibre Channel
HBAs.
On systems that use Fibre Channel, the Host Utilities installer sets the required timeout
values for Emulex and QLogic Fibre Channel HBAs. If Data ONTAP DSM for Windows MPIO
is detected on the host, the Host Utilities installer does not set any HBA values.
17.5 Setting up LUNs
LUNs are the basic unit of storage in a SAN configuration. The host system uses LUNs as
virtual disks.
17.5.1 LUN overview
You can use a LUN the same way you use local disks on the host.
After you create the LUN, you must make it visible to the host. The LUN is then displayed on
the Windows host as a disk. You can perform the following tasks:
򐂰 Format the disk with NTFS. To do so, you must initialize the disk and create a partition.
Only basic disks are supported by the native OS stack.
򐂰 Use the disk as a raw device. To do so, you must leave the disk offline. Do not initialize or
format the disk.
򐂰 Configure automatic start services or applications that access the LUNs. You must
configure these start services so that they depend on the Microsoft iSCSI Initiator service.
You can create LUNs manually or by running the SnapDrive or System Manager software.
You can access the LUN by using the Fibre Channel or the iSCSI protocol. The procedure for
creating LUNs is the same regardless of which protocol you use. You must create an initiator
group (igroup), create the LUN, and then map the LUN to the igroup.
The igroup must be the correct type for the protocol. You cannot use an iSCSI igroup when
you are using the Fibre Channel protocol to access the LUN. If you want to access a LUN with
Fibre Channel and iSCSI protocols, you must create two igroups: one Fibre Channel and one
iSCSI.
17.5.2 Initiator group
Initiator groups specify which hosts can access specified LUNs on the storage system. You
can create igroups manually or use the optional SnapDrive for Windows software, which
automatically creates igroups. Consider the following points for initiator groups (igroups):
򐂰 igroups are protocol-specific.
򐂰
For Fibre Channel connections, create a Fibre Channel igroup by using all WWPNs for the
host.
Tip: If you are using the optional SnapDrive software, use SnapDrive to create LUNs and
igroups. For more information, see the documentation for your version of SnapDrive. If you
are using the optional System Manager software, see the Online Help for specific steps.