Installation guide

Common limitations
89
Configuring a Boot Device on an EMC Storage Array
Note: The EMC-recommended method is to use LUN masking.
• CLARiiON ghost LUN — If the LUN 0 presented to a SCSI
path is not owned by the SP attached to that path, a
disconnected LUN 0 (ghost LUN) will be presented. The ghost
LUN is not write-enabled so that the MBR cannot be written to
it. Always ensure that the boot LUN is owned by the correct
SP and does not trespass at any time; trespass of the boot LUN
would result in a system crash.
◆ When attaching the Linux host to an EMC storage array, use the
adapter in the lowest-numbered PCI slot in the server. To keep the
configuration and installation simple, it is recommended that
only that single adapter be cabled to the arrays. Ensure that the
boot BIOS has been applied to the adapter.
◆ The installer installs the boot block onto only the first disk it sees.
This includes SCSI and IDE drives in the server. If only EMC
storage array devices attached to the system, the boot BIOS
should be set to the first LUN the adapter sees. If there are other
local disks in the system and depending on how Linux discovers
the controllers and drives, the boot block may need to be on a
local disk.
CLARiiON-specific limitations
◆ Prior to the installation on a CLARiiON LUN, the Linux host
must have been manually registered on the array and assigned to
a Storage Group. At least one LUN must be bound to the host's
Storage Group and owned by the SP connected to the adapter
being used for the fabric boot. The CLARiiON storage array SP
should be zoned to the lowest-numbered channel in the server
and the lowest-numbered path to the boot LUN must be the
active path.
◆ EMC recommends, although it is not required, that the boot LUN
be assigned Host LUN ID 0.
◆ During the installation procedure, it is recommended, but not
required, that only one LUN be assigned to the Storage Group for
ease of use. Once the installation has completed, additional LUNs
may be added to the Storage Group.