Apple Xsan 1.x - Manual (Page 30)

30 Chapter 3 Deployment Examples
What levels of performance do your users require?
The primary constraint on file access speed is the Ethernet network that connects users
to the file servers. By comparison, the speed of the SAN and its storage devices is not
an issue. However, if you host many users, the performance of the file servers is also
important. So, this NAS setup includes multiple servers.
How important is availability?
Users expect access to their files at all times, so high availability is critical. To address
this, the NAS example includes a standby metadata controller that can take over if the
primary controller is unresponsive.
What are the requirements for security?
Security is important in an environment where many users are sharing the same
storage. In this NAS example, security can be achieved by assigning appropriate access
privileges to users on the file servers. Because only the file servers have direct access to
the SAN, no special security setup is needed for the SAN itself.
What RAID schemes should be used for the RAID arrays?
Because availability and recoverability are important, the RAID arrays are set up to use a
RAID 5 scheme. Xserve RAID systems are optimized for high performance using RAID 5.
Which storage pools make up each volume?
The volume consists of just two storage pools, one for metadata and the other,
consisting of 5 LUNs, for user data.
How are individual volumes organized?
Again, because the primary goal here is to provide general-purpose storage, no special
organization is imposed on the available storage.
Which LUNs go in each storage pool?
All the storage is being provided by similar Xserve RAID systems configured as RAID 5
arrays, so differences in LUN performance are not an issue. We’ll create two arrays per
Xserve RAID system for a total of 6 LUNs, and then assign 5 LUNs to the user data
storage pool. 6-drive arrays permit a hot standby drive for unattended protection
during long computation sessions.
1
3 4
5 6
2
2-disk RAID 1 1
6-disk RAID 5 2
6-disk RAID 5 3
6-disk RAID 5 4
6-disk RAID 5 5
6-disk RAID 5 6
User data pool
Metadata pool