DNS virtualization storage secrets

VMware vSphere v4
Best Practices
VMware vSphere v4 is an extremely powerful virtualization software, designed to reduce costs and improve IT control.
Most storage systems provide a highly reliable, easy-to-use, high value storage platform for this deployment.
There are several factors for you to consider, however, to
ensure that the needs of your applications and data are met. This document provides valuable insight on determining the number and size of datastores, planning the storage environment, and tuning performance of the system. It is intended for storage administrators with an
understanding of VMware vSphere v4 and your storage systems.



VMware vSphere v4 includes the ESX server virtualization layer, VMware VMotion for live virtual machine migration, VMware DRS for continuous load balancing, and more. VMware ESX abstracts processor, memory, storage, and networking resources into multiple virtual machines (VMs), enabling greater hardware utilization and flexibility.

However, in order to leverage the power of VMware vSphere v4, you need to do your homework planning the deployment.
DNS recommends you do extensive performance monitoring of your VMware ESX server environment to determine the optimal number of servers and datastores. VMware publishes comprehensive material on monitoring ESX servers; please visit www.vmware.com to learn more.

Datastores
When designing your organization’s vSphere storage environment, it is important to determine the
number of datastores that best fit your virtualization needs. Factors that weigh into this decision include
the desired number of VMs, organizational design/departmental units, the use of VMware High Availability (HA) or VMware DRS, and backup and restore requirements/service level agreements (SLAs).
DNS recommends that each datastore exist on its own virtual disk (VDisk). For example, if your organization has a single ESX server with 2 datastores, you will need to create two VDisks, one for each datastore.

This provides much more granularity in how you can manage that datastore on the storage array. If you wish to expand a VDisk because the related datastore has grown near capacity or you wish to move the mailbox to a different storage tier, you can do this independently of the other datastores.
In most cases, striping each VDisk across all the available ISE in the Emprise 7000 system will meet the performance requirements of the ESX server.


Planning Storage for VMware vSphere v4.x
Prior to rolling out VMware ESX, you must first determine the I/O requirements of the VMs so you can determine the optimal number of physical spindles (disk drives) needed to support the environment.
Your applications will still have the same I/O requirements even though they are virtualized, so remember to add all I/O requirements together. Please review the appropriate technical references or white papers for the applications that you are planning to run on the ESX server to determine the I/O requirement for each.

Having an I/O pool that supports all the virtualized servers/applications is rule #1.
The second most important decision you can make when designing your VMware ESX environment is to decide on maximum performance or maximum data protection.

• ISE-RAID provides the maximum VDisk performance and usable storage capacity by having data protection handled in the ISE module itself.

• ISE-Mirror provides the maximum level of data protection by using both ISE-level and controllerlevel data protection, but the amount of usable space is decreased.

Planning assumptions for calculating IOPS:
• 10k rpm spindles = 100 IOPS
• 15k rpm spindles = 150 IOPS

Sizing the Datastores
In addition to planning the necessary I/O pool to support your applications, you will need to determine storage capacity requirements. You will need to consider:

• VM disk files
• VM swap
• Configuration files
• Redo/Snapshot files
• Metadata

Basic Sizing Assumptions
VMware has given a number of presentations at VMworld that contain formulae for calculating the
recommended storage capacity.

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