One of the types of advice I really appreciate is that which helps me to keep my options open.
I have a team from Dell in the office this week, configuring a giant pile of equipment we bought. The equipment includes a bunch of blade servers. We’ve relied on rack-mount equipment for decades, but with a push towards a private cloud we opted to jump into the early 21st century with blades. I’ve had relatively little experience with blades so it’s nice to have more experienced people around.
When I’m designing a system I always try to figure out what it’ll need to look like four years from now. Seeing the future is the hardest part of designing a system. Will our workloads increase? Will we need more CPU or storage? If we need more CPU or storage, how will we add it? Should we buy it all now anticipating the need or leave unused drive bays in an array to fill later? Will the drives be the same as the ones we have now? Will we have enough ports on the switches to grow? I even worry about things like whether the naming scheme will be flexible enough to handle growth. To compensate for this I try to give myself options, empty disk bays and RAM sockets, use 10 Gbps NICs instead of multiple 1 Gbps, etc. I’m pretty good at it with rackmount systems. Not so much with blades, yet.
Today I took our pile of Dell PowerEdge M620 blades and spread them between the M1000e blade chassis we have. The M620 is a half-height blade, so I stuck them all nicely & logically in the top row of slots, 1 through 8. I thought it looked great until a Dell guy, Tim, asked me if I’m ever going to put a full height or quarter height blade in the system.
My response, understanding immediately: “Oh, crap.”
The truth is that I don’t know if we’ll ever need a full height blade, like the Dell PowerEdge M830. Likewise with the quarter-height PowerEdge M420 and M430s, which sit four-tall inside a full-height “sleeve.” By filling the top row of the M1000e chassis I prevented myself from easily being able to add either kind. It’d be better to fill top & bottom evenly from left to right. And with a two minute change, suggested in passing by someone who has way more experience with blades than me, I kept my options open for the future.
Here’s a question for you folks: is it cheaper to make a bad or ignorant decision now and pay for it later when it needs to be fixed, or pay for the knowledgeable consultant up front so you don’t waste time and money later?
Stick your thoughts in the comments.