Installation guide

Glossary
Manual No. 775064 G-3
smallest disk in the group multiplied by the number of disks in the group.
For example, if you have 4 disks of 400MB each, and 1 disk of 200MB in a
pack, the effective capacity available for use is only 1000MB (5*200), not
1800MB.
Hot Replacement of Disks (Hot Swap)
The design of the Mylex RAID controllers allows for the replacement of
failed hard disk drives without interruption of system service. In the event of
a SCSI drive failure on a properly configured system (where the data
redundancy features of the controller are used), system service continues
without interruption. A message is generated by the system to alert the
system operator.
When a replacement drive becomes available, the system operator can
remove the failed disk drive, install a new disk drive, and instruct the
controller to “rebuild” the data on the new drive, all without interrupting
system operations.
Once the rebuild is complete, the controller will be brought back into a fault
tolerant state.
Logical Drive States
The state of a logical (system) drive can be either ONLINE, CRITICAL, or
OFFLINE. Notice that the same term “online” is used for both physical and
logical drives.
Online: A Logical Drive is in an “online” state if...
All of its participating SCSI drives are “online.”
Critical: A Logical Drive is in a “critical” state if...
It has been configured at RAID level 1, 3, 5, or 0+1; and
One (and only one) of its SCSI drives is not “online.”
A logical drive is considered “critical” because any failure of another of its
SCSI drives may result in a loss of data.
Note
I/O operation can only be performed with system
drives that are online or critical.