Eric Stewart: Running Off At The Mouth

This is what you see when you get all the cardboard out of the way.

So, we got one of the two Nexus 7710 chassis in the other day.  Forgive me for not getting any good rear shots of the chassis, but actually, there’s nothing there but fans (and the fabric blades are hidden behind them).  Moving the chassis around can be challenging to start with: even without blades, fabric, fans, or power supplies, it’s supposedly around 160 lbs.  The unit pictured here includes two 100Gb blades, a 40 Gb blade, two supervisor blades, and six power supplies.

Yes, six power supplies.  There’s room for eight.  Be sure that where ever you decide to put this beastie, you have sufficient power.  And be wary of the potential power issues.

So getting it where you want it to go can be difficult and require stripping the thing down to bare metal before you actually start moving it around.  We developed the practice of keeping ours bolted to the pallet because for some of them, the data center is only a temporary home.

6″ Vertical Cable Management

It’s also very long: 34″ or so.  This became an issue for us as our racks (APC Netshelter AR3350 42U racks, which are pretty wide and fairly deep) included 6″ cable management guides (AR7580A).

Arranging the rack included moving the front posts back to make room for the cable management, removing two of the four power pole mounts (which would still leave us with room to mount up to four power poles in the back), and moving the rear posts back as far as we could without blocking the power pole mounts.  Thing is, this still doesn’t quite give you the depth that you would ideally need for such a long chassis.

What it looks like with the bottom at U2.

Um, that’s not going to work quite right.

Ideally, you’d want the entire chassis to fit comfortably into the rack at the bottom; with a data center that provides uninterrupted power, that would mean starting at rack unit 1.  Thing is, the mounting rails for the 7710 actually dip a little below U1, and as the picture to the right attests, the rear of the chassis would have been resting on the back doorstop of the rack.  The picture to the far right is additional visual proof of the need to move up a unit in our case.  While one might think you could get away with getting rid of the frontal APC wire management, it’s not just APC that’s a problem here … but we’ll get to that.  More pictures …

Tight fit between the power pole and the chassis

Here’s a shot of the rear corner of the chassis.  Some of the power plugs will be a tight fit.  Not prohibitively so, but enough to where it might be a concern, especially if there’s more in the rack than just the chassis.  Adding two more poles (which may be desired, considering the amount of power you might need to run a full chassis) might be problematic, as you can see.

In the rack – no power supplies yet …

Back to the front: Here’s the unit in the rack – but if you look, you’ll notice the Cisco provided wire management and extended cover are not installed.  Turns out, they stick out a fair amount – almost as much as the wire management from APC. Below is a shot comparing the Cisco wire management and cover, and the APC wire management.

What would be ideal would be another couple of inches somewhere – either a longer rack (may not be ideal depending on the data center) or shorter wire management (as the pictures show, even Cisco’s wire management additions need almost as much space as the APC wire management additions do). What we have will work (basing the rails on U2 instead of U1) and the rear doors will even close … however, it will be very close.

So we eagerly await the delivery of our next 7710 (and two more 7706s). More to come …