Apple Xsan 2 User Manual
Page 47
Chapter 3
Plan a SAN
47
Choose a different primary metadata controller for each volume, and set up volume
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failover priorities to minimize the possibility of more than one volume failing over to
the same metadata controller.
If all computers on your SAN are Macs, enable Extended Attributes for your volumes
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to eliminate the overhead of file information being stored in multiple hidden files.
Availability considerations
If high availability is important for your data, set up at least one standby metadata
controller in addition to your primary metadata controller. Also, consider setting up
dual Fibre Channel connections between each client, metadata controller, and storage
device using redundant Fibre Channel switches.
WARNING:
Losing a metadata controller without a standby can result in the loss of
all data on a volume. A standby controller is strongly recommended.
Security considerations
If your SAN supports projects that must be secure and isolated from each other, create
separate volumes for each project to eliminate any possibility of the wrong client or
user accessing files stored on a volume.
As the SAN administrator, you control which computers are SAN clients. Users whose
computers aren’t SAN clients or controllers can’t browse for or mount SAN volumes.
You use Xsan Admin to remove clients from the SAN.
However, you can’t control which Xsan 2.3 computers can use a volume. Users whose
SAN computers have Mac OS X Lion or Lion Server can mount all SAN volumes
themselves.
You can also set up access control lists (ACLs) in Xsan Admin or assign user and group
permissions to folders using standard file access permissions in the Finder.
Choose RAID schemes for LUNs
Much of the reliability and recoverability of data on a SAN is provided not by Xsan, but
by the RAID arrays you combine to create storage pools and volumes. Before you set
up a SAN, use the RAID system configuration or administration software to prepare
LUNs based on specific RAID schemes.
WARNING:
If a LUN in the metadata storage pool fails and can’t be recovered, all
data on the volume is lost. It is strongly recommended that you use only redundant
LUNs (LUNs based on RAID schemes other than RAID 0) to create Xsan volumes.
For information about removing a failed LUN in a user data storage pool, see the
AppleCare Support article at .