Users Guide

FastPath

FastPath is a feature that improves application performance by delivering high I/O per second (IOPs) for the Solid State Drives (SSD). The

Dell PowerEdge RAID Controller (PERC) 9 series supports FastPath.

To enable FastPath on a virtual disk the Dell PowerEdge RAID Controller (PERC) 9 series cache policies need to be set to Write-Through

and No Read Ahead. This enables FastPath to use the proper data path through the controller based on command (read/write), IO size,

and RAID type.

For small random workloads, like OLTP, a RAID 10 array provides high performance and for sequential read dominant workloads, a RAID5

array provides high performance.

NOTE: Only IO block sizes smaller than virtual disk’s stripe size are eligible for FastPath.

NOTE: The Physical Disk Power Management feature is not applicable to FastPath-capable virtual disks.

Conguring FastPath-capable virtual disks

All simple virtual disks congured with write cache policy Write Through and read cache policy No Read Ahead can utilize FastPath. Only IO

block sizes smaller than virtual disk’s stripe size are eligible for FastPath. In addition, there should be no background operations (rebuild,

initialization) running on the virtual disks. FastPath will not be used if these operations are active.

NOTE

: RAID 50, and RAID 60 virtual disks cannot use FastPath.

The following table summarizes the FastPath-eligibility of read and write IOs across the supported RAID levels.

Table 2. FastPath eligibility across supported RAID levels

RAID 0 RAID 1 RAID 5 RAID 6 RAID 10

Read Yes

Yes

(Optimal and

Degraded)

Yes

(Optimal and Degraded)

Yes

(Optimal and Degraded)

Yes

(Optimal)

Write Yes Yes No No Yes

Virtual disk migration

The PERC 9 series supports migration of virtual disks from one controller to another without taking the target controller oine. The

controller can import RAID virtual disks in optimal, degraded, or partially degraded states. You cannot import a virtual disk that is oine.

Disk migration pointers:

• Supports migration of virtual disks from PERC H310, H710, H710P, and H810 to PERC 9 series

• Supports migration of volumes created within PERC 9 series

• Does not support migration from PERC 9 series to H310, H710, H710P, H810

NOTE

: The source controller must be oine prior to performing the disk migration.

NOTE: Disks cannot be migrated to older generations of the PERC cards.

NOTE: Importing secured virtual disks is supported as long as the appropriate Local Key Management (LKM) is supplied or

congured.

28 Features