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APPENDIX K: USING DISK MIRRORING
Disk Mirroring enables the system to write data to its internal hard disk and a connected external
USB hard drive simultaneously. When the internal hard disk is full, the system will overwrite the
previously recorded data. The same overwrite process occurs on the external hard drive (not
included).
Equal Capacity USB Hard Drive
For example, if you have a
250 GB
internal hard drive, and a
250 GB
external USB hard drive, the
system will write data to
both drives at the same time
—the external USB drive is a
mirror
of the
internal hard drive.
Larger Capacity USB Hard Drive
The system writes to the internal hard drive and external hard drive simultaneously. When the
internal hard drive is full, it begins to overwrite the previously recorded data. However, since the
external hard drive is of a
larger
capacity
, the system will continue to write data to the external
hard drive until the external hard drive is full. Once the external hard drive is full, the system will
then overwrite the
earliest
recorded data, leaving the most recent data intact as a backup.
For example, if you have a
250 GB
internal HDD, and a
500 GB
external USB HDD, the system
will write data to the internal hard drive and external hard drive simultaneously.
Once the internal hard drive is full, the system overwrites the
previously recorded data on the
internal hard drive
, but writes to the external hard drive as normal.
Effectively, half of your external hard drive will contain
early data
, and half will contain
new data
.
ATTENTION
: You
must
have Overwrite enabled on the system in order to
use disk mirroring. The connected external USB hard drive
must be of
equal or larger capacity
than the internal hard drive of the system.
250 GB
INTERNAL
HDD 0%
250 GB
EXTERNAL
USB HDD 0%
250 GB
INTERNAL
HDD 100%
250 GB
EXTERNAL
USB HDD
100%
Figure 37.0 Disk mirroring on equal capacity external HDD
