Apple Xsan 1.0 - Manual (Page 20)

20 Chapter 2 Before You Begin
• Store user files, file system metadata, and journal data on separate storage pools, and
create these storage pools using LUNs from different RAID controllers.
• Try to keep the SAN’s Ethernet network free from other traffic. Use a router to isolate
the network used by the SAN from a company intranet or the Internet, or better, use
a second Ethernet network (including a second Ethernet card in each SAN computer)
for the SAN.
• If your SAN uses directory services, mail services, or other services on a separate
server, use a second, separate Ethernet network to connect SAN computers to that
server.
• As a rule of thumb, consider that a single Xserve RAID controller, after file system
overhead, can transfer roughly 80 MB of user data per second (160 MB per Xserve
RAID system). If your SAN must support an application running on multiple clients
that requires specific throughput on each client, you can use this number to estimate
the number of Xserve RAID systems needed to support the aggregate transfer rate.
Availability Considerations
If high availability is important for your data, set up at least one standby controller in
addition to your primary controller. Also, consider setting up two Fibre Channel
connections between each client, controller, and storage device using redundant Fibre
Channel switches.
Important: Losing a metadata controller without a standby can result in the loss of all
data on a volume. A standby controller is recommended.
Also, if you have a standby controller, you can upgrade the Xsan software without
interrupting the SAN. For more information, see the Xsan Administrator’s Guide.
Security Considerations
If your SAN will support projects that need to be completely secure and isolated from
each other, you can create separate volumes for each project to eliminate any
possibility of the wrong client or user accessing files stored on a volume.
As SAN administrator, you control which client computers can use a volume. Clients
can’t browse for or mount SAN volumes on their own. You use Xsan Admin to specify
which clients a volume is mounted on.
You can also assign user and group permissions to folders you create on a volume or
use standard file access permissions to control access to other items.
Choosing RAID Schemes for LUNs
Much of the reliability and recoverability of data in a SAN is not provided by Xsan itself
but by the RAID arrays you combine to create your storage pools and volumes. Before
you set up a SAN, you use RAID Admin to prepare arrays (LUNs) based on specific RAID
schemes.
LL2652.book Page 20 Wednesday, July 28, 2004 3:45 PM