VDI Server-based Infrastructure Sizing

SUNDE VDI Server-based Infrastructure Sizing

The number of users, intended application suite and overall performance expectation determine how powerful a host system must be in order to deliver the desired end-user experience. This section provides high-level guidelines for determining the system requirements for various numbers of Diana VDI users with various computing workloads. These guidelines can be used as a starting point for sizing your deployment – but our strongest recommendation is to thoroughly evaluate expected workloads for your Virtual Machines (VMs) and expect to make some adjustments and fine tuning as your Diana virtual desktop deployment progresses.

Understanding Virtual Desktop Workloads

Prior to deployment, you should develop use cases for the users you expect to connect to a host. An important consideration in developing use cases involves determining the number and types of applications users will need to operate. These requirements help you identify and measure the users’ standard workloads. For example, you should measure the CPU, memory and storage utilization for a typical user workload in your environment. This workload data and the total expected number of users will help you determine the system requirements for your host system.

Configuring the server and storage infrastructure

Examples of Server Sizing for Medium Workload Users

Light

Workloads

Task or knowledge workers running only 1 or 2 applications; i.e. a web browser or a billing application.
Memory allocation of 768 MB (XP) to 1 GB (Windows 7) per VM .
As many as 5 – 6 or more active VMs per core can be allocated.
Storage system needs to provide roughly 30 IOPS per active user.

Medium Workloads

Knowledge workers running multiple applications simultaneously, including Microsoft Office applications.
l Memory allocation of 1 GB (XP) to 1.25 GB (Windows 7) per VM.
l About 3 – 4 active VMs per core.
l Provide around 40 IOPS per active user.

Heavy Workloads

Power users using scientific applications, high end graphics or software development.
Memory allocation of 2 GB or more per VM.
Only 2 – 3 active VMs per core.
As much as 50 IOPS per active user.
For best performance, reserve as many resources as needed.

	CPU load of a VM is highly dependent on the workload
CPU	VMs per Core: 2 – 6 Typical VM load utilizes up to 20-30% of physical CPU, equal to 3-5 VMs per core For medium workloads, allocating 3-4 VMs per core is recommended 5-6 VMs may be allocated per core for lighter workloads
	Disk performance is key to VM responsiveness
Disk	VMs per Disk (15K): 4 – 6 Both sufficient IOPS (30-50 per VM) and low latency (average read and write latency under 20 ms) required for optimal performance Enterprise-level 15K SAS RAID supports 4-6 VMs / drive excluding parity drives Lower performance disks may be used with fewer or less demanding VMs Either direct attached storage (DAS) or iSCSI / FC SANs may be used Large on-controller caches contribute greatly to storage performance Test SAN accordingly, actual results vary depending on VM workloads
	Adequate VM memory ensures a positive individual user experience
Memory	VM physical memory: 768 MB – 2 GB Depending on workload and VM OS, 768 MB – 2GB should be allocated Under-allocation of VM memory can result in Windows paging and over-burden the disk subsystem Although not desirable, the total physical memory on server can be over-allocated
	Low latency, high-bandwidth local-area network delivers full desktop experience
Network	Standard 10/100 Mb/sec networks (i.e. Ethernet) Video playback can result in higher bandwidth use Users working over internet may not get full desktop experience as in LAN due to the excessive latency and low bandwidth of most Wide-Area Networks

10 Users	20 Users	30 Users	50 Users
I7-3.2G Quad Core CPU 16 GB physical memory 500GB 10K Hard Drive	I7-3.2G Hexa Core CPU 32 GB physical memory 3 * 500G 7200K Hard Drives in Raid	Xeon-5600 Dual Core CPU * 2 48 GB physical memory 2* 1TB 15K Drives in RAID	Xeon-5600 Dual Core CPU * 2 48 GB physical memory 2* 1TB 15K Drives in RAID