we’ve got a problem with the proxy_cache feature in nginx. To be more
precise, the problem occurs when the cache loader kicks in and starts
deleting the expired files that are stored on a LVM-striped (non-raid)
ext4 partition across six huge SSD disks. The purge (sometimes?) takes
ages and it completely kills the reads from the partition.
That’s hardly an nginx issue, but it is why we would like to know if
there’s a posibility to force the cache purge so that small amounts of
files get deleted more often rather than a lot of files at once getting
deleted less often.
Also, it would help us to know just exactly how (and where) does the
nginx store the last-access-time information for each file (for the
‘inactive’ feature in proxy_cache_path directive), if the atime feature
is off for performance reasons. I’m guessing that it needs to store this
so that it knows when to delete the files. It’s quite difficult for us
to find it in the sources, so if you could point us in the right
direction, it would be awesome!