Specifications

Storage Configuration Options
Chapter 4 Storage Configuration and Management 55
Storage Configuration Options
The default storage configurations offer high levels of data security and storage
capacity with a minimum of maintenance overhead. If the default configuration is
appropriate to your needs, the only further storage configuration necessary is
creating the directory structure, establishing share access to the directories, and
setting up Snapshots.
You may have requirements or special needs that demand a different configuration.
For example, if the information on a Snap Server is mission-critical but infrequently
accessed, creating a RAID 1 with a hot spare could be a justifiable option. In another
example, some administrators prefer to keep certain sensitive data, such as financial
records, in a separate file system for added security.
This section defines your options for configuring storage on a Snap Server, and
brings to your attention dependencies that you should consider before designing
and implementing a new storage configuration.
RAIDs
The type of RAID configuration you choose depends on a number of factors: (1) the
importance of the data; (2) performance requirements; (3) drive utilization; and, (4)
the number of available drives. For example, in configuring the four disk drives of
the 4500, the decision whether to include a hot spare in the RAID depends on the
value you place on capacity vs. availability. If capacity is paramount, you would
use all drives for storage; if high availability were more important, you would
configure one of the drives as a hot spare. The following table summarizes the
advantages and disadvantages of each type of RAID:
RAID 0 (Striped)
RAID 0 distributes data evenly among all disks in the array. This technique, called
data striping, results in fast access speeds since it uses multiple physical devices to
store the data. However, RAID 0 offers no redundancy, and does not accept hot
spares. If a single disk drive fails, every file in the RAID is rendered unavailable.
RAID 0 RAID 1 RAID 5
Data loss risk high lowest low
Write access speeds fast slower fast
Cost/MB lowest high low
Disks required 1 or more 2 or more 3 or more
Accepts hot spares? no yes yes