Adaptec GDTSETUP Installationshandbuch PDF herunterladen (Seite 81)

What happens after a drive failure ?

The controller will substitute a failed Logical Drive with a Hot Fix drive only if the Array

Drive was in the ready state before the failure, or, in other words, a Hot Fix drive can only be

activated if the corresponding Array Drive had a state of data redundancy at the moment of

failure.

1. After a short while, the controller's alarm turns on.

(Note: the alarm is activated only when the Array Drive is being accessed.)

2. The controller activates the fail operation mode. In this mode, the Array Drive remains

fully operational. The data located on the failed drive is generated by means of the re-

dundancy information stored on the other drives, without causing any decrease in per-

formance.

3. The controller starts the motor of the Hot Fix drive.

4. The controller integrates the Hot Fix drive into the Array Drive and starts to reconstruct

the data and redundancy information. The Array Drive is now in the rebuild operation

mode.

Obviously, no other hard disk may fail until all data has entirely been reconstructed on the

Hot Fix drive, because up to that moment, the system is operating without redundancy.

Notes: In some literature, Hot Fix drives are also called Hot-Spare drives.

You can add or remove Hot Fix drives also with the GDTMON utility program (see Chapter

K).

95HPRYH+RW)L['ULYH

This option allows you to remove a Hot Fix Drive from an existing Array Drive. Naturally,

the Hot Fix drive must not be used up so far.

9+RW)L[3RRO$FFHVV

By selecting the Hot Fix Pool Access option, the access of a specific Array Drive to the Hot Fix

pool can be enabled of disabled.

93DULW\9HULI\

The redundancy information which is calculated during an array build or rebuild is stored on

a dedicated Logical Drive (RAID 4), or is distributed over all Logical Drives of the Array

Drive (RAID 5). This information is often called parity data. The calculation is made with an

exclusive OR function (XOR). If a Logical Drive of an Array Drive fails, its data can be re-

calculated by means of the data present on the other Logical Drives of the Array Drive and

the parity data. The Parity Verify function allows you to check the consistency of an Array

Drive's parity data.

(Note: The diagnosis program GDTMON allows an online parity verify, that is a verification

during which the Array Drive continues to be fully operational. Further details are given in

chapter K).

The verification may take quite a long time, but you can terminate it by pressing <ESC>.

1 2 ... 76 77 78 79 80 81 82 83 84 85 86 ... 92 93

Keine Kommentare

Adaptec GDTSETUP Installationshandbuch Seite 81