Server Virtualization Problems and Xiotech ISE Storage Blades

Server Virtualization (Hyper-V, VM-Ware, etc.) is making people aware of the growing crisis in SAN/storage performance. There is a solution: Xiotech ISE Storage Blades. Xiotech Storage Blades are the least expensive, least disruptive and most effective solution to the performance problems that virtualizing servers almost always seems to cause.

Is there a problem?

Anyone who has tried seriously deploying virtualization in a data center knows there is. A recent post by the ESG’s Mark Bowker makes the issue very clear.

IT sells the business on the value of server virtualization and calculates the ROI on the back of a napkin during a lunch meeting. They get the green light. … Confidence is high and they start to target the next tier of applications, such as Microsoft Exchange, and suddenly realize that the 7200RPM SATA drives they purchased to support their entire virtualization deployment may not cut the mustard

The fear is that they drop this new Microsoft Exchange VM in place and start having major performance issues… [with] their existing virtualization investment that has the compute horsepower and storage capacity available, but not the storage performance. …

As a result of all this and other similar scenarios, server virtualization deployments are stalling. 

The entire post is worth reading, but I’d like to point out the core of the issue: the typical virtualization environment “has the compute horsepower and storage capacity available, but not the storage performance.”

Why Is there a problem?

The core reason there’s a problem is that as disks get more and more capacity, they don’t get any faster. Imagine a terabyte of data in the old world, on 10 disks. If you have 5 programs asking for parts of that data, chances are pretty good it’s going to be on a disk that isn’t busy right now, so the performance will be great. In the wonderful new world, that same terabyte of data fits on just one disk. So if you have the same 5 programs asking for data, there is a 100% probability that the one disk that has all the data is already going to be busy with someone else’s request. Here is a more detailed discussion of the performance gap in storage if you’re interested.

So quite apart from virtualization trouble, storage is getting slower and slower.

Why Does Virtualization Make it Worse?

Server virtualization is an excellent thing. It helps you make more efficient use of your hardware. It does this by distributing a set of programs that need computing resource over a set of servers. This is just like running several programs on one machine at the same time, except that now we’re distributing a set of programs over a set of machines, and the programs can even require different operating systems (like Windows or Linux) and the virtualization still works. So instead of having 40 programs running on 40 machines, virtualization might let you run them on just 10 machines. A huge savings!

The trouble comes when those programs start asking for data – pesky programs, always wanting data!  Now, instead of requests coming to the storage from 40 machines, we have the same number of requests coming from just 10 machines – a 4 to 1 concentration of requests. The storage doesn’t “know” about the 40 programs. It just sees the demand for its services going through the roof. It’s like people trying to get into a ball park for a ball game. If you suddenly block off 30 of the 40 entrances and make everyone come in through the remaining 10, the lines are going to be long, the ticket takers frazzled, and everyone is going to be mad. Not unlike what happens when you virtualize servers in the average SAN environment!

We have a problem because programs running on fewer servers (because of virtualization) are trying to get to their data from fewer disks (because of increased capacity per disk).

Xiotech ISE Storage Blades to the Rescue

What made anyone think that sleek, efficient server blades would work well with the average storage mainframe in the first place? Inertia, I guess. If you’ve got linearly scalable server blades, wouldn’t you want … linearly scalable Storage blades (bricks) to go with them?

Let’s talk performance for a minute. How about:

10,000 Exchange users per 3U ISE

And then add a second for 20,000 users, a third for 30,000 users, and so on. Here is a post with details on how others attempt to meet the need, a video about the benchmark, etc.

There is certainly a problem. The amount of money going into expensive SSD’s tells us there’s a problem. Stalled virtualization projects tell us there’s a problem. Xiotech ISE Storage Blades with awesome performance that doesn’t degrade as the device fills up are the solution. There is even software that makes setup painless in a VM environment!

Comments

[Tom MacMillan]

is this a blog or just a paid advertisement from Xiotech? It's a stupid argument based on a flawed assumption - that all of your data is on 'one disk'. There are storage systems with large disks that also virtualize the data, so even if you use very large disks, many of them are working for you - its never 'one one disk'.

[David B. Black]

I'm a techie who works for a firm that has an investment in Xiotech, and many of my posts are about our companies, as I disclose in my bio. While this is not a "paid advertisement" from Xiotech, there is definitely self-interest here.
That having been said, there is wide acknowledgment in the storage industry that the increasing capacity of disks leads to performance issues, for the simple reason that head movement and rotational speed have changed little in the last 10 years while disk capacity has gone up dramatically. And of course SAN's virtualize over many disks -- but for a given capacity, they have many fewer disks than in the past.
The problem is seen the most in applications that really need high storage performance; the ESG post that I quote states this view clearly. (ESG is the storage industry's leading analyst group.) So if this is a "stupid argument based on a flawed assumption," then I have loads of company -- including the many storage users who are swallowing hard and buying SSD storage devices that are hugely expensive in $/GB terms -- but at least they perform.