User guide

Technical white paper | HP Enterprise Virtual Array Storage and VMware vSphere 4.x and 5.x configuration best practices

Best practice for zeroing

• For improved performance, when performing zeroing activities on two or more Vdisks concurrently, it is best to have the

Vdisks ownership evenly spread across controllers.

Best practice for XCOPY

• XCOPY operations can benefit from increased performance when different EVA controllers own the source and

destination datastores.

• When an HP EVA Storage array is in degraded mode, such as when one of the two controllers is down, the proxy

relationship between the two controllers will also be affected. Under this condition, only the remaining controller will

process all XCOPY and zeroing operations in addition to servicing non-VAAI I/Os. Therefore, when the EVA is in a degraded

mode, VAAI operations should be avoided.

Best practice for degraded EVA

• When the EVA is in degraded mode, avoid using VAAI operations.

VAAI and Business Copy and Continuous Access

HP EVA Storage local and remote replication of a Vdisk generates additional workloads for the diskgroups servicing this

Vdisk. The EVA VAAI implementation has carefully taken into consideration the tradeoffs that exist between speeding up

VAAI workloads versus equally servicing other important non-VAAI workloads without performance impact. Therefore, when

using VAAI primitives on a Vdisk that is in a Business Copy or Continuous Access relationship, administrators should expect

throttled VAAI performance gains.

Best practice for Business Copy and Continuous Access

• When using VAAI on Vdisks that are in snapshot, snapclone, mirror clone, or continuous access relationships VAAI

performance may be throttled.

VAAI operation concurrency

HP EVA Storage will allow VAAI cloning and zeroing operations or any combination of them to be performed concurrently

and in parallel to other VAAI and non-VAAI operations. However, as previously discussed, the HP EVA Storage array VAAI

implementation was also carefully designed to only allow VAAI operation a finite amount of system resources in order to

reduce the performance impact on external and internal non-VAAI I/O workloads. This is a design choice that guarantees

that VAAI clone/zeroing operations adequately share storage array resources and bandwidth.

Following the VAAI best practices discussed in this guide will provide the best performance to VAAI clone and zeroing

operations while maintaining adequate I/O latencies and throughput for VAAI and non-VAAI workloads.

VAAI clone and zeroing operations offer the benefit of increased performance to VM cloning, VM template creation and VM

initialization. However, queuing multiple concurrent such operations may induce undesired latency to the overall system

affecting the performance of VAAI and non-VAAI workloads. Therefore, it is best to keep the number of concurrent VAAI

operations to a minimum, which will help keep VAAI performance high and lower the performance impact on non-VAAI

workloads.

Best practice for concurrent VAAI operations

• Minimize the number of concurrent VAAI clone and/or zeroing operations to reduce the impact on overall system

performance.

• An inadequate number of physical disk spindles in a disk array can bottleneck the performance of any disk subsystem

despite cache sizes, controller count or speed. To benefit from the performance advantages of VAAI and concurrent VAAI

operations, it is critical that the deployed HP EVA Storage array is configured with an adequate minimum number of hard

drives. The following table provides minimum estimates for the number of drives needed to achieve adequate VAAI copy

rates with Vraid5 Vdisks. Note that these estimates are dependent on the overall I/O workload of the system.