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Article Number: 000138022

A PERC 5 RAID controller creates concatenated arrays when mixed drives sizes are used when creating RAID 10 or RAID 50 virtual disks

Summary: PERC 5 creating concatenated RAID 10 or RAID 50 arrays when using mixed drives sizes

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Article Content

Symptoms

Article Summary: This article provides information about a PERC 5 creating concatenated RAID 10 or RAID 50 arrays when using mixed drives sizes


 

Issue: 


When creating RAID 10 or RAID 50 multi-level RAID arrays using mixed drive sizes the resulting Virtual Disk is a concatenated array. 

The PERC 5 User Guide states that each array will be reduced in size based on the size of the smallest array member.  This applies only to the Primary RAID Level (RAID 0, 1, 5) and does not take into account multi-level RAID arrays (RAID 10, 50).  In a RAID 10 or RAID 50 array each of the Primary RAID Levels is reduced in size based on the smallest array member.  In the RAID 10 or RAID 50 array, if the Primary RAID Levels are different sizes, they will be concatenated together rather than being striped together.

For example:  Three 500GB drives and one 250GB drive are used to create a RAID 10 (Figure 1).  The result would be:

  • Span 1 consisting of two 500GB drives mirrored.  500GB contributed to the RAID 10 array size.
  • Span 2 consisting of one 250GB drive and a portion (250GB) of the 500GB drive mirrored.  250GB contributed to the RAID 10 (Span 2 is reduced since the smallest drive is 250GB).
  • The total size of the RAID 10 array would be 750GB.

SLN167282_en_US__1RAID10
Figure 1: Example of RAID 10
 

Note: Later controllers reduced the entire array by the smallest drive. For example, on an H700 controller, using three 500GB drives and one 250GB drive would result in a RAID 10 array with striped spans of 250GB each for a total of 500GB available space in the array.

 

Article Properties

Affected Product

Servers

Last Published Date

10 Apr 2021

Version

3

Article Type

Solution

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