[tlbuild] tlmgr/install-tl bug: running out of disk space

[Simon Dales]

On Sat, 2022-03-05 at 08:34 -0400, George N. White III wrote:
> Filling up storage and continuing to hammer it with added processing
> that will fail is hard on the media and can reduce performance or
> even result in a corrupt filesystem when cached metadata can't be
> saved. I have encountered systems that become read-only for users
> when a disk hits some capacity threshold, typically 85%.   For TL
> installs, it would be reasonable (and helpful) to warn users if the
> targeted storage is more than 85 or 90% full.

Writing a universal spare-space system is fraught with difficulties,
especially when we have to make it work cross-platform.
Accuracy/pleasing everybody/...?

And TL maintainers can't know you have a twitchy filesystem that
reserves 15% of capacity. Or you set it to zero, or 20%.

Maybe use a reasonable measure and warn the installer. If you have a
new 10TB disk then TL will fit easily in the corner. But an old 100GB
would be harder pushed. It's upto a wise sysadmin.

Could say something like:
* "TL may need about 10GB, <1% of estimated 1234GB free. OK?".
* "TL may need about 10GB, 83% of estimated 12GB free. OK?". 

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/// error behaviour

Then there's the behavior on fail to write, like when the filesystem
refuses. It's all very well saying Ctl-Z etc, but can't control remain
within the user interface?

Looking at file copiers/installers such as synaptic and konqueror: they
warn on read/write errors. Up comes dialog with cancel/retry/...
buttons,  you press them and do whatever.

Also doing two-stage copy helps. So copy all you will be needing from
DVD/www to HDD. Internet/DVD maybe slow and/or errors. Then expand the
tarballs within the same filesystem. Does peak at about double the
install size at peak, but on most platforms space is cheap (?).

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Simon