Clone Mode - Sans Digital ELITERAID ER104UT+(B) Detailed User's Manual

ER104UT(-B)
It is also possible to create a LARGE volume using only a single hard disk drive connected to Port 1. However, it is not
possible to expand an existing LARGE volume by adding another hard disk drive and still preserve any existing data on that
volume.

2.3 CLONE MODE

The CLONE MODE storage policy stores all data in duplicate on separate drives to protect against data loss due to drive
failure. One drive clones the others at all times. Every write operation goes to all drives. CLONE MODE provides the
highest level of data protection for critical data that you cannot afford to lose if a hard drive fails, but waste the amount of
storage capacity because all data must be stored to all drives. The resulting storage capacity of the virtual CLONE volume
will be equivalent to the size of one hard drive (if all drives are the same) or the smallest of the all drives (if they are
different).
If drive fails (Maximum four drives), the CLONE volume is still usable, but it is in a vulnerable state because its cloned hard
drive is inaccessible. When the offline drive comes back online, the appliance begins a rebuild process immediately one by
one (if they are more than one fails) to restore data redundancy. A message appears in the LED indicator to notify you that
a rebuild is in progress.
Although the volume remains available during the rebuild process, the volume is susceptible to data loss through damage to
the remaining drive until redundancy is restored at the end of the rebuild and verification process. Host access takes
precedence over the rebuild process. If you continue to use the CLONE volume during the rebuild, the rebuild process will
take a longer time to complete, and the host data transfer performance will also be affected.
It is also possible to create a CLONE volume using one hard disk drive connected to Port 1 of the ELITERAID ER104UT(-B),
although no clone will occur until a second hard disk drive is connected to Port 1. With only one hard disk drive
connected, the CLONE volume will be available, although no data protection will be provided until a second hard disk drive
is connected.
9