In response to my recent articles about blades, one that focused on RLX and another about how Dell could rock the blade market, many of ZDNet's readers wrote in to say that the comparison of 1U-sized rack-mountable servers ("What's a 'U'?") to blade alternatives was not only a legitimate one to make, but also highly relevant to the decisions they've either already made or are in the process of making.
I'm becoming increasingly bearish about blades when compared to other server form factors, such as 1Us. (That term comes from their unit of measurement. A server by that name is 1.75 inches thick.) So bearish am I, that in the traditional marketspeak of "razors and blades", I'm beginning to wonder whether the server blades aren't really the razors, and the management software to run those servers doesn't fall into the category of the blades.
Blade servers are like video or network cards that you snap into a slot in a PC. The difference is that instead of snapping them into a PC the way one would with a video card, the card (henceforth, "the blade") snaps into a slot in a special enclosure that can hold other blades. Each blade is an entire, self-contained server (usually an Intel-based one) that might include on-board storage. When storage is not on board, the blade is normally connected to networked storage such as a storage area network (SAN) or network-attached storage (NAS). Blades typically share resources with other blades. Those resources -- power supplies, networking switches, storage switches and so on -- can usually be found in the same enclosure as the blades that share them. Blades from one vendor, however, do not fit into enclosures from another.
First-tier blade vendors Hewlett-Packard and IBM and their second-tier competitors, such as RLX, Egenera and Verari (Dell won't be serious about blades until November), talk about blades as though they're the best thing since sliced bread for everyone. But are they? I'm not so sure. As far as I can tell, the greatest benefits of blades are the ones that are most difficult to quantify in terms of total cost of ownership (TCO).
For example, since much of the aforementioned resource sharing takes place through a backplane that's inside the enclosure, a blade deployment is typically void of the cable nests that might be found in server deployments involving other form factors, such as 1Us and towers. Blade vendors actually compete on the number of cables you can expect to eliminate with a fully loaded enclosure. But beyond the minimal costs that are associated with the cables themselves, cable elimination is a convenience. For some shops that have hundreds or thousands of servers that are frequently being moved (either from one enclosure to another or because of failure), this convenience may be a very important one. The same can be said for hot-swapping -- a feature that allows blades to go live on the network just on the basis of being inserted into an enclosure -- no powering up or down of anything is required.
But these are conveniences and, as it turns out, many shops that have gone with blades just plugged them in and left them much the same way they would have done with their 1Us. It's not that most server administrators wouldn't like to have these modern day server conveniences (redoing the tie wraps for the cables on my server racks was never my favourite thing to do), but the question that Dell raises, the one that was the impetus for my last column on the topic, is a fair one: should you have to pay a lot more for this convenience?
Talkback
Sorry, but David's article is substiantially incorrect, and he is either guessing or just misinformed. His comments suggest that the $1B spent this year on blades was done out of ignorance and stupidity, and lacks financial or business judgement. He may be bearish on blades, the market knows better.
The idea that 1U's are better than blades is simply a ridiculous statement. In many ways. blades are far superior, which is why they are selling so well. Let's examine some facts here, not just idle speciulatoin.
I understand why David is confused about TCO. While writing a article professing his expertise about blades, he apparently doesn't know the difference between IBM, RLS or Verar designsi. There is a huge difference and it all relates to TCO.
1U servers are inexpensive and hence known as "disposable" computing. Problem is, people keep disposing of them because they keep burning up. Heat is a serious challenge for 1U servers. This is due in part to the small, inefficient and unreliable 1" fans. Some servers have upwards of 10 per server, and they only move about 30cfm combined. Not enough, especially for the units on top of the rack that are known for melting face plates off, or even catching fire.
Verari eliminated this problem by mounting blades vertically, removing the small fans which resutled in a thinner blade, and for each row of 11 vertically mounted blades, they insert a row of 8 5" fans. With one of their models, they achieve 4 rows of blades and fans, front and back, totalling 88 dual processor nodes in 10 sqft, and they're moving 100sqft/blade using 64 high volume fans. This creates a wind tunnel effect, such that even if a fan or two fails, the overally airflow is far more than is need to sufficiently cool even the hottest processor.
this solution no only keeps blades running much cooler, but the overall HVAC requirement for the fans is well below that of the 800-900 smaller fans need to inefficiently cool the same number of processors in a 1U config. Oh wait, you can't get that many 1U's in 10 sqft. can you?
So, Verari solved the heat problem, got this highest density in the industry, and did so whilre consuming 30% less power and AC tonage than comparable 1U confgurations, which, BTW, would use twice the data center floor space. And that costs money too. There is definiitely a strong TCO story here, one you missed.
The imaginative writing about how no one cares about costs because of all the excess HVAC, AC and floor tiles as a result of the .com implosion is simply a fanatsy. David should get out more.
Blades are here to stay, and as everyone else tries to figure out how to beat Verari (their cooling technology is patented), I'll stick with a proven winner. Maybe that's why Verari technology built 2 of the 8 largest supercomputers in the world.