Best Practices for Implementing VMware vSphere in a Dell PS Series Storage Environment Abstract Dell EMC recommended best practices for configuring VMware vSphere hosts connecting to Dell PS Series storage arrays.
Revisions Revisions Date Description August 2013 Initial Release August 2013 Added best practices around CHAP and ACL December 2014 Added: ESXi v5.5 EQL FW v7.0 Updated: Delayed ACK / LRO December 2015 Added: ESXi v6.0, PS Series FW v8.0, NOOP Timeout, Virtual Volumes Moved to appendix: ESX v4.1, ESX v5.0/5.1 Removed: LRO September 2017 Added: ESXi 6.5, EQL FW v9.x Removed ESX v4.1, ESX(i) v5.0/5.1 November 2019 vVols branding update The information in this publication is provided “as is.
Table of contents Table of contents Revisions.............................................................................................................................................................................2 Table of contents ................................................................................................................................................................3 Preface .......................................................................................................
Preface Preface Dell™ PS Series arrays optimize resources by automating performance and network load balancing. Additionally, they offer all-inclusive array management software, host software, and free firmware updates. The information in this guide is intended for VMware® and PS Series storage administrators and installers. Related software and firmware used for the preparation of this paper Vendor Model Software Revision Dell PS Series storage firmware 9.x VMware VMware vSphere®/ESXi™ 6.
Introduction 1 Introduction As more organizations are virtualizing datacenters that use both VMware vSphere and PS Series storage, best practices and configuration guides such as this one, help to keep these environments running smoothly. These best practices and recommendations are a combination of various technical report guidelines as well as knowledge provided by the technical support staff at Dell EMC. Various documents provide extensive detail on how to configure some of the recommended settings.
Host based connectivity and high availability 2 Host based connectivity and high availability Several best practices should be implemented when connecting VMware vSphere/ESXi servers to PS Series storage to ensure optimum performance and high availability. 2.1 Keep ESXi updated to current revision It is important to ensure that the most current ESXi version, also known as the build number, is installed.
Host based connectivity and high availability Note: In a VMware vSphere environment, this allows rapid movement of datastores between clusters. By unregistering the VMs, changing the ACL and rescanning, entire volumes or datastores can be moved between clusters. Using CHAP helps with scalability, as well as ease of management.
Host based connectivity and high availability This script sets all PS Series volumes to Round Robin and the IOPS value to 3. This script can be copied into the console or an SSH session to make it easier. This script must be run on each ESXi host accessing PS Series storage.
Host based connectivity and high availability 2.5.4 Default iSCSI login and Noop timeout values In addition to configuring Round Robin or MEM for multipathing, there is a recommendation for the host iSCSI login and Noop timeout settings. These timeout values might be too low in large environments and prevent paths from reconnecting or potentially cause an all paths down (APD) event. By default, the MEM configuration script attempts to set Login timeout values to the recommended 60 seconds.
Host based performance 3 Host based performance 3.1 Delayed ACK Delayed ACK is a TCP/IP method of allowing segment acknowledgements to piggyback on each other or other data passed over a connection with the goal of reducing I/O overhead. Example of Delayed ACK from Multivendor Post on using iSCSI with VMware One side effect of delayed ACK is that if the pipeline is not filled, acknowledgement of the data is delayed. In SANHQ, this can be seen as higher latency during lower I/O periods.
Host based performance • Setting the Delayed ACK property globally for the iSCSI initiator a. Under Adapter Details, select Advanced Options and click Edit. b. Scroll down to Delayed ACK. c. Deselect the checkbox and click OK • Setting the Delayed ACK property for an individual discovery address a. b. d. e. f. Under Adapter Details, select Targets, Dynamic Discovery. Select the discovery address to modify and click Advanced. Scroll down to Delayed ACK.
Host based performance 9. Return to Configure > Storage > Storage Adapters > iSCSI Software Adapter > Adapter Details > Targets and select Dynamic Discovery again. 10. Add the PS Series storage Discovery address, but do NOT rescan the adapter yet. 11. From the Dynamic Discovery listing, select the discovery address to modify and click Advanced. 12. Scroll down to Delayed ACK. 13. Deselect the checkbox for DelayedAck in the Inherited column. 14.
Datastore size and queue depth 4 Datastore size and queue depth While administrators continually try to maintain an optimized data layout and performance, the size of the datastore becomes a question. Because every environment is different, there is no hard-set number. However, you will find recommendations of 10-30 VMs per datastore. A number of factors in this decision include speed of the disks, RAID type and workload intensity of the VMs.
Virtual machine considerations 5 Virtual machine considerations Apply best practices on a virtual machine to allow increased performance. One of these is changing the disk timeout values to 60 seconds. For Windows® guests, the VMware tools typically do this by default. For more information on the disk timeout setting recommendations, refer to the OS Initiator Guide in the PS Series Firmware download section of the support site at support.dell.com/equallogic (this site requires a login).
Data Drives 6 Data Drives There are four primary ways to connect data drives to VMs in a VMware vSphere and PS Series storage environment, assuming that the C:\ or /root drive of the guest OS is located on a VMFS datastore volume. • • • • 6.1 VMDK on VMFS iSCSI in the guest (sometimes called direct connect, or storage direct) Raw Device Mapping (RDM) Virtual Volumes (vVols) VMDK on VMFS A VMDK disk on a VMFS volume is the most commonly used practice for data drives.
Data Drives 5. For VMs that are supported, change the controller type from LSI to a Paravirtual SCSI adapter for better performance. Note: Paravirtual SCSI adapter support and configuration information is located in the VMware KB article 1010398. 6. Expand the details of the newly listed SCSI controller by clicking >. 7. In Change Type, select VMware Paravirtual from the list. 8. 9. 10. 11. 13 Expand the details of the newly listed hard disk by clicking >.
Data Drives The Dell EMC support staff has seen tremendous performance improvements by making these few changes. Note: Virtualized RDMs and VMDKs prior to ESXi v5.5 are limited to 2TB-512b in size in all versions of ESX. 6.2 iSCSI in the guest VM You can take advantage of iSCSI in the guest VM by using the guest VM iSCSI software initiator. This also allows vMotion and all of the other VMware tools to work. Advantages: • • • • Isolates the data drives for Data Protection/DR strategies.
Data Drives • • 6.2.1 Requires storage team intervention. Since it is a brand new volume, you need to create the volume to be seen by the VM not the vSphere environment. This means installing and configuring the iSCSI software initiator, connecting to the SAN with proper pathing, configuring and formatting the volume to be seen by the VM. Needs to be considered for DR plans separate from VMs.
Data Drives 6. In the Settings window, click Teaming and failover and select Override under Failover order. 7. Make one of the physical NICs active and set the other to standby (not unused). Do this for the other iSCSI guest port group and use the other adapter. This prevents the guest OS from detecting a link failure. Host MPIO algorithms typically pause I/O for a short time before declaring a path dead. Using a standby prevents this I/O delay.
Data Drives 6.3 Raw Device Mapped LUNs Raw Device Mapped LUNs (RDMs) are used to isolate the data on volumes and retain the view inside vCenter.
Conclusion 7 Conclusion As more environments become virtualized, it is necessary to follow best practices to maintain not only the performance of these environments, but also the high availability. Dell EMC recommends following these practices even if there is no apparent performance issue as it increases the likelihood of the environment being in a known healthy state. 18 Best Practices for Implementing VMware vSphere in a Dell PS Series Storage Environment | TR1091 | v1.
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