So something I truly hate to see when visiting computer rooms is fibre cables hanging in the breeze with no dust covers,  their precious glass connectors exposed to the world.
Even worse are fibre patch panels and HBAs without dust covers.
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When new equipment arrives, every HBA, every patch panel port and every fibre optic cable will have a dust cover.
So what to do with these little guys once you remove them?
Keep them!
When you unplug a cable later you need to immediately re-install those precious covers both onto the cable and into the HBA or patch panel port, to protect the fibre optics from contamination.
I recommend storing dust covers in sealed plastic bags, preferably kept in the relevant rack so they are close to hand.
The picture below (taken from the rear of an XIV) is cute in that it shows a clever re-use of the XIV power cable covers,
but the dust covers are now exposed to contamination from the open air.
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Since we are on the subject, take note of the colour coded power cables in the XIV.
Its another example of clever design to make power redundancy visually obvious. 
The ends of the power cords are red, yellow and green to indicate which of the three UPSs these cables come from.
The unused cords at the top of the image are free because this machine is not fully populated with modules.