User Guide

Both CTIO and FastPath provide enhanced performance benefits to SSD volumes, as they can fully

capitalize on the lower access times and latencies of these volumes.

FastPath provides IO performance benefits to rotational HDD-based volumes configured with Write

Through and No Read Ahead cache policies, specifically for read operations across all RAID levels and

write operations for RAID 0.

Configuring FastPath-Capable Virtual Disks

All simple virtual disks configured 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 10, 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

Read Yes Yes

(Optimal and

Degraded)

Yes

(Optimal and

Degraded)

Yes

(Optimal and Degraded)

Write Yes No No No

In addition, FastPath-capable virtual disks are characterized by the following:

• The presence of CacheCade virtual disks on a controller disables the FastPath capability of all eligible

HDD virtual disks. Eligible SSD virtual disks are still FastPath-capable.

• Secured virtual disks are not FastPath-capable.

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

• The addition or removal of a redundant path does not affect the FastPath-capability of virtual disks.

Virtual Disk Migration

The PERC H710, H710P, and H810 cards support migration of virtual disks from one controller to another

without taking the target controller offline. The controller can import RAID virtual disks in optimal,

degraded, or partially degraded states. You cannot import a virtual disk that is in an offline state. Disk

migration pointers:

• Supports migration of VDs from PERC H700 and H800 to PERC H710P and H810

• Supports migration of volumes created within H710, H710P, or H810

• Supports migration of volumes created on H310 to H710, H710P, or H810

• Does not support migration from H700 or H800 to H310

• Does not support migration from H710, H710P, or H810 to H310

• Does not support backward migration from H310, H710, H710P, H810 to H800 and H700