Entries 02, 06, 07 and 08 of the standing index, written out
Five categories, and the rule that decides what counts as one item
An inventory is useful for exactly as long as the word item keeps meaning one thing. SCARLETGENT LTD counts five categories and no others; anything that fits none of them is written into the notes, where it can be read, rather than into the count, where it would quietly distort every figure drawn from it.
The five categories
- Devices
- Anything with a power lead and an address of its own: switches, access points, printers, the machine under a desk, the box the line arrives on.
- Links
- Every run between two devices or between a device and a socket, patch lead or permanent cabling, recorded by both of its ends.
- Accounts
- Every login that reaches any of the above, including service logins and the ones nobody has signed into for a year.
- Renewals
- Anything carrying a date: a licence, a domain, a certificate, a support arrangement, a lease on a line.
- Records
- The documents that already describe some of this. They are counted as items because they age exactly like the things they describe.
One item is one thing somebody can stand in front of
The test for a device is physical: if two people can walk to it and agree they are looking at the same object, it is one item. A stack of two switches is two items, because either of them can fail on its own. A single enclosure holding one board is one item, however many ports are on the front of it.
For links the test is different, and it is the stricter of the two. A link is recorded when both of its ends are recorded — the port at one end and the socket at the other — because a run written down from one end only is a cable disappearing into a wall, and it will be pulled by somebody who believes it goes nowhere. Where only one end could be found, the run is listed as unterminated and stays that way until somebody has stood at both ends of it.
Accounts get a third test, and it is a question rather than a measurement: who uses this, or what needs it? An account that answers neither is still counted, and is listed plainly by name, so that a decision about it can be taken in daylight instead of being inherited by whoever comes next.
What the count is for
Once the devices and the ports are counted, capacity stops being a matter of opinion. The ports on the wall are the number of switches multiplied by the ports on each; the spare capacity is that figure less the ports with something live in them; and the moment the spare reaches nothing, the next device needs a switch rather than a cable. The port-count sheet on the standing index does that arithmetic step by step on figures you type in, so the step itself is visible and can be argued with.
The same count carries the renewals. A list of dates is only as good as the list of things those dates belong to, which is why renewals are counted with the devices rather than kept somewhere separate where they can fall quietly out of step.
How the count becomes a document The port-count sheet on the index