[squid-users] squid 3.5.27 does not respect cache_dir-size but uses 100% of partition and fails

[Alex Rousskov]

On 07/11/2018 04:39 AM, pete dawgg wrote:

> cache_dir aufs /mnt/cache/squid 75000 16 256

> FATAL: Ipc::Mem::Segment::open failed to shm_open(/squid-cf__metadata.shm): (2) No such file or directory

If you are using a combination of an SMP-unaware disk cache (AUFS) with
SMP features such as multiple workers or a shared memory cache, please
note that this combination is not supported.

The FATAL message above is about a shared memory segment used for
collapsed forwarding. IIRC, Squid v3 attempted to create those segments
even if they were not needed, so I cannot tell for sure whether you are
using an unsupported combination of SMP/non-SMP features.

I can tell you that you cannot use a combination of collapsed
forwarding, AUFS cache_dir, and multiple workers. Also, non-SMP
collapsed forwarding was primarily tested with UFS cache_dirs.


Unfortunately, I cannot answer your question regarding overflowing AUFS
cache directories. One possibility is that Squid is not cleaning up old
cache files fast enough. You already set cache_swap_low/cache_swap_high
aggressively. Does Squid actively remove objects from the full disk
cache when you start it up _without_ any traffic? If not, it could be a
Squid bug. Unfortunately, nobody has worked on AUFS code for years
(AFAIK) so it may be difficult to fix anything that might be broken there.


Cheers,

Alex.