# The Spare I Did Not Buy

I skipped the second power supply to save a hundred bills,
and paid it back with interest in a week of sitting still.

The unit was redundant. That was what the label said.
Two bays, two rails, two everything, and one of them was dead

from the day I bought it secondhand, though I had never known,
because a redundant system with one half gone still runs alone.

That is the whole trap, stated plainly, and it is not clever:
redundancy is invisible until it fails forever.

A single-supply server tells you loudly when it goes.
A dual with one already dead behaves like nothing shows.

Nine months in, the working half gave out at half past four,
and the machine went dark as though it had one supply, no more.

The replacement took eleven days. The model was retired.
The seller had one left in stock across an ocean, as required.

Here is where I concede, and it is not a small concession:
you cannot stock a spare of every part in your possession.

Spares cost money, spares go stale, spares sit and gather dust,
and the part that finally fails is the one part you did not trust.

The rule I keep is narrower. Stock the parts that are discontinued,
and the parts whose lead time is longer than your outage can be continued.

And what will get you then is not the part. You will have that.
It is that the spare has sat unpowered in a cupboard flat

for two and a half years, and when you finally slot it in
you learn that capacitors go bad in storage, not just in.