Sep 03

Can you get your fan tray out?

Network hardware vendors are challenged with the need for a fan tray in their chassis. The fan is something that probably won’t go away for a very long time, yet it’s a piece of equipment that can fail. Some chassis have fan trays that are very easy to get out and replace, the Cisco ONS 15454 is one of those chassis. The Cisco ONS 15454 has a fan tray that is removed from the front and it simply pulls out.

Other chassis have the fan tray in a location that cause a problem with being blocked by the data cables. The Cisco 6513 is a great example of a fan tray that can easily be blocked by the data cables. If you are not familiar with the 6513, the line cards are horizontal in the chassis. The air flow needs to go side to side, so the fan is on the left. To avoid the fan tray, all data cables would need to come from the right side of the switch to be connected. This can be a very difficult challenge due to the quantity of cables that the 6513 can support.

On almost all of the network devices that I have seen, the vendor has done their best in the placement of the fans. They usually don’t have a choice on the location of the fan. If it was a different chassis design, then the fan would be in the way somewhere else.

I believe that it is our responsibility to correctly run the cables to avoid the fan tray. I have spent hours labeling and disconnecting cables just to replace a failed fan tray. If the cables were run correctly, the fan should be removed and replaced with out disconnecting any cables. No outage should ever be required to replace the fan tray.

Here are a few chassis that I have seen with very good Fan tray design.

Cisco Nexus 7010
Cisco ONS 15454
Brocade MLX-16

Here are a few chassis that can be challenging to cable and avoid the fan. Maybe the location of the fan tray could be better, maybe not.

Cisco 4500’s
Cisco 6500’s
Cisco 7600’s
Brocade SX800

What chassis have you used that have good or bad fan tray locations?
Have you ever had to take an outage to replace a fan tray?
Please tell us about it!!!

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Aug 06

Don’t forget to remove the fan tray screw on a Brocade SX800 chassis

When Brocade ships chassis switches, some of them have a single screw holding the fan tray in place. That screw is only there to keep the fan tray in place during shipping. Brocade does a good job of placing a yellow sticker on the front of the fan tray informing the tech to remove the screw before racking.

Recently one of my coworkers racked a Brocade SX800 and started cabling it. When I was in the data center, I noticed the yellow sticker was still on the chassis. I reached down and pulled on the fan tray to find that it wasn’t coming out.

My co-worker wasn’t pleased with himself when I informed him of the yellow sticker and the screw. He then unracked the SX800 and removed the screw.

I was glad that I found this before we had loaded the chassis up with clients, then had a fan failure. If that would have happened it would have been a lot of work just to get the fan tray replaced.

Have you have had to replace a fan tray that you couldn’t get out of a chassis?
If so, tell us about it and how much work and time it took!!

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