Ricardo Wurmus <[email protected]> writes:
> Today we discovered a few more things and discussed them on IRC. Here’s > a summary. > > /var/cache sits on the same storage as /gnu. We mounted the 5TB ext4 > file system that’s hosted by the SAN at /mnt_test and started copying > over /var/cache to /mnt_test/var/cache. Transfer speed was considerably > faster (not *great*, but reasonably fast) than the copy of > /gnu/store/trash to the same target. Turns out that space on the SAN is insufficient for a full copy of /var/cache. We’ve hit ENOSPC after 4.2TB. The SAN enforces some headroom to remain free, so it denies us full access to the 5TB slice. Bummer. I guess we’ll have to wait for the SAN extension some time early 2022 before we can relocate the substitutes cache. Should we attempt to overwrite /gnu/store and rely exclusively on substitutes from the cache? No matter how we look at it, the huge store is a performance problem for us. Today I had to kill ’guix gc’ after the GC lock had been held for about 24 hours. We will keep having this problem. -- Ricardo
