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IBM-AUSTRIA - PC-HW-Support 30 Aug 1999 |
Disk Array States
Array State Transitions
The movement between states is illustrated in the following diagram.
Disk Array States
A disk array can be in one of the following states:
- Good
The array is online and it can be read and written. Both member
disk drives of the array are present. No data rebuilding is
outstanding. The array is fully protected against the loss of
one member.
- Exposed State
One member is missing from the array. The first write operation
causes the array to enter the degraded state.
After an interval, if a hot spare is available, it replaces the
missing member and the array enters the rebuilding state.
- Degraded State
One member is missing and a write operation has been received
for the array. Read and write operations to the array are supported. If
a hot spare disk drive is available, after an interval, the hot spare
replaces the missing member and the array enters the rebuilding
state.
The missing member is permanently excluded from the array.
- Rebuilding State
The array is online and it can be read and written. Both
members of the array are present but data is being rebuilt on one of the
members.
- Offline State
An array is in this state when one of the following conditions exists:
- Both members of the array are missing or have failed.
- One member of the array is missing when a failover occurs.
- The rebuilding of a replacement member is not complete when the remaining original member fails.
Read and write operations to the array are not supported.
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