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
RAID 0 stripes and has no redundancy. RAID 1 mirrors. RAID 5 and RAID 6 use parity, and RAID 6 survives two disk failures. RAID 10 stripes mirrors. The calculator does arithmetic on numbers you type. The rebuild estimate is not a measurement of your array.
The only copy of data does not belong on RAID 0. A parity rebuild is a long read of the surviving disks. Write that down before you choose it. This page does not start a rebuild and does not mkfs anything.
Disk names and IOPS are inputs you measured or you are still guessing. Label which. 192.0.2.10/24 and example.com are documentation. They stay in the note.
The change you can finish
Apply nothing while you are writing the note. When the lab window opens, it is one change on the host named in the ticket. Read the draft, then the host, then decide.
Rollback is the file, the package version, or the snapshot you saved first. You do not invent a rollback after the only copy is gone.
- Name the array and whether it is the only copy.
- Pick a level and write why.
- Run the calculator with numbers you label as measured or guessed.
- Read the rebuild estimate as an estimate.
- Do not rebuild anything.
- Stop.
Mistakes that outlive the command
RAID Levels Compared goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- RAID 0 for the only copy.
- A rebuild started from the calculator.
- Guessed numbers treated as a measurement.
- A failed disk ignored because the page was open.
Decisions to write down
One decision for RAID Levels Compared: The level matches the copy rule. Numbers are labeled. No rebuild was started. The only copy is not on RAID 0. And the estimate is not a promise.
Checks before you call it done
Confirm this before you call the change done: The level is written. The copy rule is written. Numbers are labeled measured or guessed. No array was changed. And a second person can say why that level. If one of those fails, stop.
| Level | Survives | Do not use it for |
|---|---|---|
| 0 | No disk failure | The only copy |
| 1 | One disk in the mirror | Capacity you have not counted |
| 5 | One disk | A rebuild you have not timed |
| 6 | Two disks | A small array you have not planned |
| 10 | Disks in different mirrors | A guess at the disk count |
# RAID 0 has no redundancy.
# Do not rebuild from this page.
# An estimate is not a measurement.Before you leave the host
RAID Levels Compared ends when the hostname in the prompt matches the hostname in the ticket. If it does not, you are on the wrong host. Stop. A command that succeeded on the wrong host is not progress.
The draft stays a draft until a person has read the names in it. A generator does not log into the host and does not know which disk is empty. You delete a line that names a host, a path, or an account you did not write down.
192.0.2.10/24, gateway 192.0.2.1, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. They belong in the note. They are not values you leave on a host because a draft included them.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, or a token you save in the ticket or in git. The real secret stays in the password store.
One change is the window. If two things move and the result is wrong, you will not know which one did it. The next change 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 change produces a host nobody can rebuild. Restore the copy you took first.
A second person reads the hostname and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the host alone.
This page is a planning guide. It is not a vendor manual, not an official standard, and not permission to touch a host you do not administer. You do not disable a firewall, AppArmor, or SELinux to make a check pass.
Tools for this guide
These tools run in the browser on this site. They do not log into your machines.
Related pillar guides
More in this cluster
The pillar for this page, and the next published pages filed with it.