Apple Xsan 1.4 - Manual (Page 45)

Chapter 2 Setting Up a Storage Area Network 45
Xserve RAID supports all popular RAID levels. Each RAID scheme offers a different
balance of performance, data protection, and storage efficiency, as summarized in the
following table.
RAID 10, 30, and 50 schemes assume the use of AppleRAID software striping and aren’t
appropriate for use with Xsan, which performs its own striping. For more help choosing
RAID schemes for your arrays, see the Xserve RAID User’s Guide or the Xserve RAID
Technology Overview (at www.apple.com/server/documentation/).
Deciding on the Number of Volumes
A volume is the largest unit of shared storage on the SAN. If your users need shared
access to files, you should store those files on the same volume. This makes it
unnecessary for them to pass copies of the files among themselves.
On the other hand, if security is critical, one way to control client access is to create
separate volumes and mount only the authorized volume on each client.
RAID level
Storage
efficiency Read
performance Write
performance Data
redundancy
RAID 0 Highest Very High Highest No
RAID 1 Low High Medium Yes
RAID 3 High to very high Medium Medium Yes
RAID 5 High to very high High High Yes
RAID 0+1 Low High High Yes