This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
Power usage effectiveness divides total site power by the power that reaches the IT equipment. The calculator does that division on numbers you type. It does not read a meter. A lower number means less overhead only if both inputs were measured the same way.
One site you administer. Write the period. A nameplate used as IT load makes the ratio look better than the meters. This is not a certification and not a contract.
Cooling and the rack page own the watts. This page owns the ratio.
The change you can finish
Apply nothing during the writing of the note. When the lab window opens, it is one change on the device named in the ticket. Read the draft, then the device, then decide.
Rollback is the file or the revision you saved first. You do not invent a rollback after the only copy is gone.
- Write IT power and total power.
- Say measured or nameplate.
- Read the ratio.
- Write the period.
- Do not publish it as a guarantee.
- Stop.
Mistakes that outlive the command
PUE and Data Center Efficiency goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- Nameplate called measured.
- A ratio with no period.
- The number called a certification.
- A site you do not administer.
Decisions to write down
One decision for PUE and Data Center Efficiency: Both inputs are named. The source is honest. The period is written. The result is a ratio. And no promise was published.
Checks before you call it done
Confirm this before you call the change done: IT power is written. Total power is written. The ratio is written. The period is written. And the note does not call it guaranteed. If one of those fails, stop.
Before you leave the device
PUE and Data Center Efficiency ends when the hostname on the device matches the hostname in the ticket. If it does not, you are on the wrong box. Stop. A command that succeeded on the wrong box is not progress.
The draft stays a draft until a person has read the names in it. A generator does not log into the device and does not know which interface is the uplink. You delete a line that names a device, a zone, or a prefix you did not write down.
0.0.0.0/0 is not kept because a sample included it. A source you can say is the source you keep. 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. They belong in the note. They are not prefixes you type onto a production device because they appeared in a draft.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, a community string, or a pre-shared key you save in the ticket or in git. The real secret stays in the store.
One change is the window. A VLAN and a routing protocol and a VPN do not share it. If two things move and the result is wrong, you will not know which one did it. The next feature waits for its own page.
If the same step fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied config produces a device nobody can rebuild. Restore the copy you took first.
A second person reads the device name and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the device alone.
This page is a planning guide. It is not a vendor manual, not an official standard, and not a permission to touch a network you do not administer. The pillar guide owns the wider design. This page owns one lab proof.
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