Apple Xsan 1.x - Manual (Page 31)

Chapter 3 Deployment Examples 31
Which clients should be able to access each volume?
The real SAN clients in this example are the file servers that users connect to. Each of
the servers should have access to the SAN volume for maximum availability.
Which computers will act as controllers?
To avoid dedicated controllers, one of the file servers will act as the metadata controller
and a second file server will be configured as a standby controller.
Do you need standby controllers?
High availability is a high priority, so a second file server is also configured as a standby
controller so it can take over the role of metadata controller if necessary.
Do you want to use controllers as clients also?
The controllers in this example are the real clients of the SAN, so each is set up to act as
both client and controller.
Where do you want to store file system metadata and journal data?
Data in this example is delivered to users over Ethernet, so the performance of the SAN
itself is not as critical as when clients are connected directly to the Fibre Channel
network. However, to ensure good volume performance, we’ll create a separate storage
pool for metadata and journal data.
What allocation strategy?
Data in this volume is stored in a single storage pool of five LUNs. Because there is only
one user data storage pool, allocation strategy is not an issue, so we’ll accept the
default allocation strategy: Round Robin.
What block size and stripe breadth should we use?
Because shared network storage typically involves lots of files and many small,
randomly positioned reads and writes, we’ll use the relatively small default file
system block size of 4 KB together with a 256-block stripe breadth for the storage pool.
This should provide good space utilization.