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!