Volumes And Raid; Table 37 Raid Quick Comparison - ZyXEL Communications NSA-2400 User Manual

Table 36 Storage > Overview (continued)
LABEL
Capacity
Status

7.3 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-
2400 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.
Back up your data before deleting or re-creating a volume!
For example if you originally have two disks configured at RAID 1, and you then buy two
more disks and want to configure all four at RAID 5, you should first back up all your data on
those disks (see the Genie Backup Manager 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-2400. 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 37 RAID Quick Comparison

RAID Level
Number of Disks
Capacity
Storage Efficiency
Fault Tolerance
Availability
Read Performance
Write Performance
NSA-2400 User's Guide
DESCRIPTION
This field shows the size of the disk in GB.
This field displays OK if the (physical) disk is readable and Down if no
data can be read from it. If Down, the disk may need to be scanned for
errors or replaced. If it needs to be repaired or replaced, then you will
have to resynchronize the volume.
0 1
2,3,4 2
S*N S*N/2
100% 50%
None YYYY
Y YYYY
YYYY YYY
YYYY YYY
Chapter 7 Storage Screens
5 10
4 4
S*(N-1) S*N/2
(N-1)/N 50%
YYY YYYY
YYYY YYYY
YYYY YYYY
YY YYY
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