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Chapter 7 Storage
NSA320 User’s Guide
168
7.6 Storage Technical Reference
This section provides some background information about the topics covered in
this chapter.
7.6.1 Volumes and RAID
A volume is a storage area on a disk or disks. You can create volumes on the
internal disks and external disks attached to the USB port(s). You can spread a
volume across internal disks but not between internal and external disks.
RAID (Redundant Array of Independent Disks) or JBOD is the storage method that
the NSA uses. The storage method you use depends on how many disks you have
and how many volumes you want to create. It’s important that you consider this
carefully as all data is deleted when you re-create a volume.
Note: Back up your data before deleting or re-creating a volume!
For example if you originally have one disk configured as JBOD, and you then
install another disk and want to configure the two disks to use RAID 1, you should
first back up all your data on the two disks (see the Memeo Autobackup utility on
the included CD) and then restore your data later after you create the new volume
type.
Below is a table that summarizes some attributes of the various RAID levels as
supported on the NSA. For capacity and storage efficiency, “S” is the size of the
smallest drive in the array, and “N” is the number of drives in the array.
Storage efficiency assumes all drives are of identical size.
Performance rankings are approximations.
Table 25 RAID Quick Comparison
RAID Level 0 1
Number of Disks 2 2
Capacity S*N S*N/2
Storage
Efficiency
100% 50%
Fault Tolerance None YYYY
Availability Y YYYY
Read
Performance
YYYY YYY
Write
Performance
YYYY YYY