Sometimes it’s hard to understand hardware design (no pun intended). I can understand there are complex requirements, depending on what’s being designed. Today I stumbled on what I’d call a pretty odd design flaw, but can see why it was done with poor foresight.
In this case, I’m referring to the design of HPs DL365 G5 servers. Particularly the decision for the location of the storage controller’s battery. I understand that 1U servers have some very specific, and complex requirements, such as:
- Must fit all the stuff in a small space
- Must have good air flow
- Must provide easy access to hot-swap parts
Earlier this month we got an alarm on a server that the battery had gone bad, and was no longer holding a charge. I scheduled downtime, made sure we had a battery on hand, put in a change ticket, and set to work.
After powering down the server, and removing the top cover, I set out to find the battery. The storage controller was next to the memory banks, and had 3 cables coming from it. 2 were obviously for the HDD back planes, the third, a little thinner, disappeared behind some fans, and into the front of the case.
If you take a look at the picture to the right, and look above the center fan bank, you can see a thin black cable disappearing under the chassis. A closer look is in this picture. From the front, it’s hiding right above the middle drive behind this grill.
To remove the fan bank is a project on its own. Dell uses nice quick release containers, squeeze some colored tabs, and stuff just pops apart. To get these out, I had to use a flathead screwdriver to pry the metal tabs out the way. Well, they’re not really tabs. They were about 2 inches long, and about the same deep, and not flexible in the slightest.
Once removed, it should be a simple case of pulling on a small black tab. This is where the design flaw comes in (as if the fact its hidden in there to begin with isn’t bad enough). These storage batteries have a tendency to swell as they get older, even more so as they reach the end of their life. If you look at the picture to the left, you can see the bulge already. Why is this a problem? Well 2 reasons, the first being fairly obvious… If it’s bulging, there is a chance for it to explode, or leak, all over the inside of the server, in particular onto the hard drives below it. The second, is the design flaw, the battery is nicely wedged between 2 sheets of rivited metal, and when the battery swells, it does NOT want to come out.
It can take some ‘gentle’ pursuasion to evict the battery from it’s sanctuary without puncturing the first cell on the little board. In this case, I had to use a flat head screwdriver, and go through the grill at the front of the chassis above the drives to push it, while I carefully pulled from the other side at the same time. There is a few more pictures of the swollen battery here, but this one shows it pretty well.
The battery was probably put in that location because it was the only free space left. Little consideration was taken for maintenance, or hardware faults, such as swelling batteries. I believe the G7 series has this issue resolved though.