Freedom9 4020 - Manual (Page 98)

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the same size, the smallest of the disks determines how much disk space is available for
data, similar to RAID 5.
• RAID 10: RAID 10 is similar to RAID 1, but rather than having one disk mirror to one other
disk, two disks mirror to the two other disks.
You can use RAID 10 only if your storage system has four disks. The disks in the first two
slots constitute the first pair, and the disks in the second two slots constitute the second pair.
In each pair, the smaller of the two disks is used for data, and the larger of the two disks is
used as the mirror.
If one disk in the pair fails, the other disk continues to make its data available.
A.1 Adding Hard Disks
The effect of adding hard disks to your storage system varies, depending on the disk
configuration you chose when you configured the system and the current state of the existing
disks.
For example, in a linear configuration, you can add a new disk at any time, and data can be
written to that disk as soon as it is added. Whether you previously removed a disk or one of the
other disks failed makes no difference.
In a RAID configuration, the effect of adding a disk varies, depending on whether the RAID is in
a normal or degraded state (as indicated on the Disks page). A normal state indicates that the
RAID is functioning properly. A degraded state indicates that one or more disks have been
removed or failed, but because of the data protection offered by the RAID, you can continue to
access all the data.
In a normal state, you cannot add a disk to a RAID 0 or RAID 1 configuration. Any disk that you
install will not be used unless you subsequently reconfigure the storage system.
Warning: Reconfiguring your storage system disks deletes all the data on your
storage system.
However, if you currently have three disks and a RAID 5 configuration, you can add a fourth disk
as a spare (essentially changing from RAID 5 to RAID 5 + spare while retaining all your existing
data).
In a degraded state, you can add a disk to a RAID at any time, and the new disk will be rebuilt to
replace the disk that was removed or failed.
Warning: If the RAID has failed—that is, if so many disks have failed or been
removed that the RAID can no longer function—you must either re-install the
disks or reconfigure the entire storage system, deleting all the data on your
system.
Adding hard disks to a linear or normal RAID configuration
To add a hard disk to a linear or normal RAID configuration:
1. Insert the hard disk into the storage system. You can do this whether the storage system is
powered on or off.
2. Access the Manager or refresh the browser window to open the Disk Change Notification
page (Figure A-1).