Maxim Cournoyer <maxim.courno...@gmail.com> writes: > Hi, > > Ludovic Courtès <l...@gnu.org> writes: > >> Hi, >> >> Maxim Cournoyer <maxim.courno...@gmail.com> writes: >> >>>> We could consider setting up a rsync module on ci.guix (aka. berlin) if >>>> that helps. >>> >>> The main issue I had seen (but it seems that'd affect most rsync >>> mirroring scheme) is that the files could be updated while an rsync >>> client is syncing them, which could perhaps lead to corrupted/incomplete >>> nars on a mirror in the worst case? >> >> I don’t think that’s the case because ‘guix publish’ creates narinfos >> and nars atomically (see ‘bake-narinfo+nar’ and ‘compress-nar’). >> >> That is, the worst that can happen is that the rsync client copies >> temporary files corresponding to incomplete nars or narinfos, but these >> files are not going to be served. > > OK! I guess we could try the simplest path first and complicate it if > there are issues with it. There already is a rsync service exposing > /var/cache/guix/publish on berlin: > > --8<---------------cut here---------------start------------->8--- > (rsync-module > (name "substitutes") > (file-name "/var/cache/guix/publish")) > --8<---------------cut here---------------end--------------->8---
Good to know! I think it's already exposed? --8<---------------cut here---------------start------------->8--- $ rsync --list-only rsync://berlin.guix.gnu.org/ web-pdf web-video web-audio web-cuirass web-cuirass-manual disarchive substitutes web-guix-hpc-videos --8<---------------cut here---------------end--------------->8--- > So it'd be a matter of opening the rsync port in Berlin's firewall/MDC > infra. I'd have preferred to have this done on hydra-guix-129 still > though, to avoid adding IO load to Berlin, which is critical to keep GC > times low, but given the current size of the publish cache, it lacks the > storage capacity for it (it only has a < 10 TiB SAN slice available, the > SSDs are now used as extra storage for the data service, IIRC). > > I guess clients would want to add rsync options to transfer only the > newer items, and only to some maximum amount (e.g. 5 TiB), as > 25 TiB > or similar probably won't be practical for many setups, which would > incur lots of IO on Berlin, another reason for keeping the nars cache > size in check.
