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Keep the personal disk three starts back

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Copied before every start of the machine, and kept several deep rather than
copied over one file.

ONE BACKUP TAKEN AT EVERY START IS WORSE THAN NONE. The way a disk is lost is
that something goes wrong - and the very next thing anybody does is start the
machine again to see how bad it is, which is exactly when a single backup gets
overwritten by the wreckage. Three deep means the damage has to happen and then
be started past three times before the copy that would have helped is gone.

AND IT IS NOT GUARDED BY A CHECK THAT THE DISK STILL LOOKS RIGHT, because no
such check can be written. The disk that went missing this week was a perfectly
valid and perfectly empty filesystem: the format had succeeded, and there is
nothing to look at that says a disk has lost anything. That is the whole reason
to keep the old ones rather than to judge the new one.

The backups sit outside clean's reach like the disk itself. A backup a rebuild
deletes is not one.

The message the disk prints when it is first made said "nothing in this makefile
will touch it again", which stopped being true the moment this was added. It now
says written to, and says where the copies go.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
This commit is contained in:
Anachronaut
2026-09-01 15:54:55 -04:00
co-authored by Claude Opus 5
parent c1b3c4c156
commit 925388c2f2
3 changed files with 49 additions and 7 deletions
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Programs/CosmOS/README.md
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@@ -951,6 +951,13 @@ drive made of memory in **drive 2**. The scratch drive is what `osTakeScreen` wr
1 is yours and comes after nothing, so adding the scratch drive later did not renumber it. It is made the
first time it is needed and then left alone: never rebuilt, never cleaned, never committed.
It is **copied** before every start, though, and kept three starts back. One copy taken at
every start would be worse than none: a disk is lost when something goes wrong, and the next
thing anybody does is start the machine again to look, which is when a single backup gets
overwritten by the wreckage. Nor is the copy guarded by any check that the disk still looks
right, because no such check can be written - the disk that went missing here was a perfectly
valid and perfectly empty filesystem, because the format had succeeded.
That last part is the point. Everything else in this repository is made from source and can be
thrown away without losing anything - but a disk is where something *made on the machine*
lives, and a disk that `make clean` deletes is not a disk of your own. It sits outside