During VMworld Europe 2013, I have attended session STO5638 “Best practices with Software Defined Storage”, presented by Chad Sakac (EMC) and Vaughn Stewart (Pure Storage). During this very interesting session, the past, present and future of storage was outlined and lots of useful information, tips and tricks were presented.
Last week while reviewing the configuration of a storage device, I remembered one of their recommendations; “Stay current on best practices”. VMware sets the baseline, so over the years, VMware has published a lot of recommendations on designing, sizing and configuring all components of a vSphere environment. But there is also a large Partner Ecosystem and most of these Partners do also publish Best Practices related to their products. Several of my customers have implemented a Dell Equallogic Storage solution, so time to find out if Dell can add some extra value. For readers not particularly interested in Dell Equallogic products, skip to the “Recommendations” section, or continue reading.
Dell Equallogic Best Practices
The latest version of these Best Practices can be found here. After a brief introduction, recommendations are grouped in the following sections:
- Host based connectivity and High availability.
- Host based performance.
- Datastore size and Queue depth.
- Virtual Machine considerations.
- Data drives and a final conclusion.
While reading the document, the majority of the recommendations were already familiar to me. But some are new, or at least remarkable. A few highlights:
- The latest version was not updated to ESX 5.5.
- Since ESX 5.1, the Storage Heartbeat VMkernel port is no longer required. In case you are running an older version of ESX, configuring Storage Heartbeat is still recommended. In case you are using Jumbo frames; do not forget to also configure the Storage Heartbeat VMkernel port for Jumbo Frames.
- In case you are not running on VMware vSphere Enterprise (Plus) licenses, you are not allowed to install the (highly recommended) Dell Equallogic Multipath Extension Module (MEM). If MEM is not an option, the recommended Path Selection Policy is VMware’s Round Robin.
- In addition to the previous recommendation, it is recommended to set the iSCSI LoginTimeout value from 5 (default) to the maximum value of 60 seconds.
- It is also recommended to disable the delayed ACK on the iSCSI initiator. VMware KB 1002598 “ESX/ESXi hosts might experience read or write performance issues with certain storage arrays” provides detailed information on this issue.
- Dell Equallogic also recommends disabling Large Receive Offload (LRO). In case you are deploying Linux based VM’s, VMware has published KB 1027511 “Poor TCP performance might occur in Linux virtual machines with LRO enabled”.
- When it comes to connect storage to your VM’s, the document presents a nice comparison (and best practices) between VMDK on VMFS, iSCSI in the Guest VM and Raw Device Mapped LUNs.
- When configuring a VMDK on VMFS, one recommendation is to create a second virtual SCSI adapter for the second disk. I could not find much support for this recommendation. See also this post by Duncan Epping.
- If you are running pré Windows 2008 or older Linux distributions, mind the disk aligning issue.
- Applications like Exchange or SQL benefit from formatting a disk with a cluster size of 64K (this better aligns with the 64 K stripe size of the Equallogic box.
- Regularly, check for an updated version of relevant Best Practices.
- While preparing for a vSphere upgrade, have a look at Best Practices (again).
- Do not take everything for granted, and do some additional research.
- Read other Best Practices and/or VMware knowledge Base articles.
As always, I thank you for reading and I welcome your comments.