IBM Support

Capacity in RAID 6 array is less than expected - Servers

Troubleshooting


Problem

The user creates a RAID array with RAID level 6 with an odd number of drives. After the array is created, the amount of usable space is less than expected. With our current documentation, when assigning RAID level-6 to a logical drive, the capacity is reduced by the capacity of two drives (for data-parity storage). This second set of parity information is added to improve fault tolerance.

Resolving The Problem

Source

RETAIN tip: H192265

Issue

The user creates a RAID array with RAID level 6 with an odd number of drives.

After the array is created, the amount of usable space is less than expected. With our current documentation, when assigning RAID level-6 to a logical drive, the capacity is reduced by the capacity of two drives (for data-parity storage).

This second set of parity information is added to improve fault tolerance.

Affected configurations

This tip is not machine specific.

This tip is not option specific.

This tip is not software specific.

Additional information

This configuration is working as designed.

HARD DRIVES CAPACITY
4 2
5 2.5
6 4
7 4.66
8 6
9 6.75
10 8
11 8.8
12 10
13 10.83
14 11.67
15 12.5
16 14

 

Document Location

Worldwide

Operating System

System x Hardware Options:All operating systems listed

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Document Information

Modified date:
29 January 2019

UID

ibm1MIGR-5073789