guix size should account for hard links in its disk space calculation

Consider the following operating system declaration:

$ guix size `guix system build robot-framework-system.scm`

gives:

store item total self

/gnu/store/f9fy1b2yf1qxy523732r7z34ymwqz64b-linux-libre-5.1 241.5 241.5 21.8%

/gnu/store/1lcniyxkxkh8g73zvh2gpbccvl6ggna7-locale-2.28 91.8 91.8 8.3%

/gnu/store/zm3188ipzi262s0m8bxm24br77yh9pd8-python-3.7.0 183.0 74.6 6.7%

/gnu/store/h8l1pby3cm6b4fxsfwwr65b4d1hyh6cs-python-3.7.0 183.0 74.6 6.7%

/gnu/store/wqr8rwnwpmag01i6kb0laf62vsqnhrxy-python-3.7.0 183.0 74.6 6.7%

/gnu/store/b7fqhszxl02g6pfm3vw6b3cjz472qrly-python-3.7.0 182.8 74.6 6.7%

[...]

total: 1106.3 MiB

But,

$ guix size `guix system --no-grafts build robot-framework-system.scm`

store item total self

/gnu/store/f9fy1b2yf1qxy523732r7z34ymwqz64b-linux-libre-5.1 241.5 241.5 28.4%

/gnu/store/1lcniyxkxkh8g73zvh2gpbccvl6ggna7-locale-2.28 91.8 91.8 10.8%

/gnu/store/b7fqhszxl02g6pfm3vw6b3cjz472qrly-python-3.7.0 182.8 74.6 8.8%

/gnu/store/ybglr7nfs8v9kpnm8vf4drg3gafnvd15-guile-static-stripped-2.2.4 45.9 45.9 5.4%

total: 851.2 MiB

Conclusion: the size of grafts is added multiple times even though they

should be very light on disk usage given that they are mostly hard links

to the original, ungrafted output.

Salut Maxim,

Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:

I think there should be an option to take hard links into account, but

it should probably not be done by default. There are cases (e.g., when

using ‘guix pack’ or when evaluating the amount of data that will

actually be transferred over the wire) where you want to know the

“apparent size”, ignoring hard links.

Note that it’s a bit more work to take hard links into account since

currently ‘guix size’ just queries each store item’s size to the

daemon.

Thanks,

Ludo’.