News
1/10/2011
12:55 PM
George Crump
George Crump
Commentary
50%
50%

Desktop Virtualization And Local Storage - Just Say No

There is an ongoing debate about what type of storage is best to use to support desktop virtualization solutions, especially in small to medium sized implementations. Storage is one of the most expensive parts of a desktop virtualization project and as a result anything you can do to drive cost out of the storage purchase is going to make desktop virtualization economics work better. This leads some to advocate local storage.

There is an ongoing debate about what type of storage is best to use to support desktop virtualization solutions, especially in small to medium sized implementations. Storage is one of the most expensive parts of a desktop virtualization project and as a result anything you can do to drive cost out of the storage purchase is going to make desktop virtualization economics work better. This leads some to advocate local storage.The theory goes that local storage is going to be a less expensive and an easier to implement solution for the virtual desktop project. At the surface those are valid points but when you weigh what you give up by not going to shared storage and how you have to configure local storage to provide users with a respectable desktop experience I'm not sure if local storage is quite the deal it sounds like.

First let's look at what you have to do to local storage to get it ready for desktop virtualization. From a performance perspective you are going to need enough drives to generate enough IOPs to provide adequate performance to those now virtualized desktops. While the typical working IOPs requirement of a virtual desktop is relatively light, typically less than 5 IOPs. However the per virtual desktop IOP during boot up, logon/logoff, software update operations that number can increase substantially, as much as 5X. As we discuss in our recent article "Solving Boot Storms With High Performance NAS" these activities are the real challenge in the environment and something that needs to be planned for when designing the storage system.

Providing your virtual desktop environment with high performance and highly reliable storage is not as simple as running down to your local computer store and picking up that $99 2TB hard drive. You're going to want something a little more enterprise class with a 15K RPM speed. Most environments will either use RAID 1 or RAID 5 for data protection so that will require a more expensive controller to be purchased and the protection overhead will eat into performance. The need for performance and reliability is typically going to require an eight to ten drive RAID configuration. This drive count is going to be beyond the internal drive capability of most servers, which means an external storage system.

The combination of faster drives and an external chassis erodes some of the price advantage compared to mid-range storage systems but not all of it. Its the limits of locally attached systems in this type of configuration that become the real challenge. Most price competitive external systems can only be expanded so far. As you add virtual desktops you may need additional external systems, which adds to the cost and to complexity.

As we discussed in our webinar "Making Sure Desktop Virtualization Won't Break Storage" there is some planning required vs local storage. That planning though is often worth what you gain from shared storage. The big give up with local storage is that you loose much of what desktop virtualization brings like virtual machine migration and server balancing. You need shared storage to be able to migrate machines and balance load. You also give up the ability to offload from the hypervisor all the things that shared storage does well like scalability, snapshots, cloning, deduplication and replication. While its true that some of these functions can be performed via software all of those come at an added cost of not only dollars but also server resources. Finally shared storage can be leveraged for other storage uses, like server virtualization, as well so the cost of the shared storage investment can be allocated across several projects.

Local storage may have a roll to play in desktop virtualization but you have to weigh all the odds. Is desktop virtualization without shared storage really going to give you a return on the investment? If you factor everything in, you may be better off getting shared storage first and then deploying virtual desktop later than you would be to live with an virtual desktop project that under achieves due to poor storage performance. One thing we have seen consistently is once users get a bad taste for virtual desktop, they rarely will give it a second chance.

Track us on Twitter: http://twitter.com/storageswiss

Subscribe to our RSS feed.

George Crump is lead analyst of Storage Switzerland, an IT analyst firm focused on the storage and virtualization segments. Find Storage Switzerland's disclosure statement here.

Comment  | 
Print  | 
More Insights
Register for Dark Reading Newsletters
White Papers
Cartoon
Current Issue
Dark Reading Tech Digest, Dec. 19, 2014
Software-defined networking can be a net plus for security. The key: Work with the network team to implement gradually, test as you go, and take the opportunity to overhaul your security strategy.
Flash Poll
10 Recommendations for Outsourcing Security
10 Recommendations for Outsourcing Security
Enterprises today have a wide range of third-party options to help improve their defenses, including MSSPs, auditing and penetration testing, and DDoS protection. But are there situations in which a service provider might actually increase risk?
Video
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2013-4440
Published: 2014-12-19
Password Generator (aka Pwgen) before 2.07 generates weak non-tty passwords, which makes it easier for context-dependent attackers to guess the password via a brute-force attack.

CVE-2013-4442
Published: 2014-12-19
Password Generator (aka Pwgen) before 2.07 uses weak pseudo generated numbers when /dev/urandom is unavailable, which makes it easier for context-dependent attackers to guess the numbers.

CVE-2013-7401
Published: 2014-12-19
The parse_request function in request.c in c-icap 0.2.x allows remote attackers to cause a denial of service (crash) via a URI without a " " or "?" character in an ICAP request, as demonstrated by use of the OPTIONS method.

CVE-2014-2026
Published: 2014-12-19
Cross-site scripting (XSS) vulnerability in the search functionality in United Planet Intrexx Professional before 5.2 Online Update 0905 and 6.x before 6.0 Online Update 10 allows remote attackers to inject arbitrary web script or HTML via the request parameter.

CVE-2014-2716
Published: 2014-12-19
Ekahau B4 staff badge tag 5.7 with firmware 1.4.52, Real-Time Location System (RTLS) Controller 6.0.5-FINAL, and Activator 3 reuses the RC4 cipher stream, which makes it easier for remote attackers to obtain plaintext messages via an XOR operation on two ciphertexts.

Best of the Web
Dark Reading Radio
Archived Dark Reading Radio
Join us Wednesday, Dec. 17 at 1 p.m. Eastern Time to hear what employers are really looking for in a chief information security officer -- it may not be what you think.