Rack or Blade?

Blade server technology has been around for a few years
now, and yet we don't see organizations falling over each other to deploy the
same in their data centers. Rack servers are still the preferred solutions.
There were several reasons for this. One possible reason, at least in the Indian
context could have been that they were exorbitantly priced. Another was that
each individual blade was not as powerful as a rack server in terms of computing
power. For instance, you could go for a powerful 8-way ordinary rack server to
run your enterprise applications, but the same was not available in a blade. The
earliest blade server that I recall seeing was fitted with an IDE hard drive,
and could take up to two processors. This was sufficient to run ordinary,
smaller applications such as file and print for individual departments, a web
server, etc, but not enough for running enterprise applications. Smaller
organizations couldn't afford them in anyway, and found individual pedestal
server solutions to be more feasible. So there wasn't much logic in going for
the technology. That's why they were projected to be an ideal solution for
running clustered applications, but not for enterprise applications. Things seem
to be changing now, which could possibly make them a more viable solution than
ordinary rack servers. Let's see how.

Anil Chopra, Associate Editor

Let's start with some of their key benefits. One is of
course that they pack much more server density in the same area as a normal
rack. Given the growing complexity of enterprise IT infrastructure, blade
servers can be a boon, as they help consolidate resources, and make them easier
to manage. For instance, the solution from one of the blade vendors offers 8
full blades or 16 half blades per enclosure, and you can have up to six such
enclosures in an ordinary 42U rack. So in effect, you could have either 48 or 96
blade servers in a single 42U rack. Moreover, today you can have up to 4
processors in a single server blade with up to 16 GB of memory. That's
sufficient computing power for most enterprise needs. Moreover, given the
onslaught of multi-core processors, it won't be long before you could have
8-way server blades containing four dual-core CPUs.

Efficient storage and networking are some of the other
benefits of blades. Once again, I remember seeing each server blade fitted with
an IDE hard drive back when they were introduced. Today, you can have fiber
switches fitted into the same enclosure as the blade servers, allowing them to
be directly connected to a SAN. You can of course fit in regular Ethernet
network interconnects to connect them to the main network. This results in a lot
of saving on the cabling front, compared to ordinary rack servers.

Centralized power and cooling are the other benefits that
blades offer. Instead of having individual SMPSs power each blade, there's a
single power enclosure that goes inside the rack, which can provide power to an
'x' number of blade enclosures. This makes them far more power efficient.

In effect, the overall blade design is very modular. If
something doesn't work, you can simply pull it out and replace it with
something else without disrupting the remaining elements. Likewise, you can have
whatever your business needs now, and keep adding more computing power to the
same rack as the need arises. Plus, this sort of a modular design makes it
easier to manage as well. For instance, each blade has a couple of LEDs to
indicate its status. There are also LEDs in the back to identify which blade is
connected to which network port. Specific solutions are also available to manage
entire blade server solution.

All this doesn't mean that there are no problems with
blade servers. Even now, there doesn't seem to be a single standard that all
vendors follow. If one vendor fits 48/96 blades in a 42U rack, another fits 60.
The dimensions of the blade enclosures themselves are different, meaning you
can't have a mixed vendor environment in a blade solution. Ordinary rack
servers on the other hand don't have this problem. You're not restricted to
purchase racks from a select few vendors. You can buy various configurations at
various price points. This gives you the flexibility of choosing what you need
and from whoever you want.

The other challenge in blades is to get the application
support for the same. As the highest number of CPUs per blade is still 4, you
can't have a large enterprise application requiring more than 4 CPUs to run on
the same. This problem could soon be taken care of with multi-core CPUs coming
into the picture.

But with blade prices coming down, they're becoming a
more feasible solution even for medium sized organizations. One problem that
will always remain is that of server density. While it's good to have more
computing power in the same space, it also puts more weight per square foot of
floor space.