Hi all, We host around 240 departmental and campus web sites (individual afs volumes) across 6 virtual web servers on AFS storage. The web servers are 4 core, 16G VMs, and the 4 file servers are 4 core 32G VMs. All CentOS 7 systems.
In the past week or so, we've encountered high-load on the web servers (primary consumers being apache and afsd) during periods of increased traffic, and we're trying to identify ways to tune performance. After seeing the following in the logs: 2021 11 08 08:52:03 -05:00 virthost4 [kern.warning] kernel: afs: Warning: > We are having trouble keeping the AFS stat cache trimmed down under the > configured limit (current -stat setting: 3000, current vcache usage: 18116). > 2021 11 08 08:52:03 -05:00 virthost4 [kern.warning] kernel: afs: If AFS > access seems slow, consider raising the -stat setting for afsd. I increased the disk cache to 10g and the -stat parameter to 100000, which has improved things somewhat, but we're not quite there yet. This is the current client cache configuration from one of the web servers: Chunk files: 281250 > Stat caches: 100000 > Data caches: 10000 > Volume caches: 200 > Chunk size: 1048576 > Cache size: 9000000 kB > Set time: no > Cache type: disk Has anyone else experienced this? I think the bottleneck is with the cache manager and not the file servers themselves, because they don't seem to be impacted much during those periods of high load, and I can access files in those web volumes from my local client without any noticable lag. Any guidance on what to look at regarding performance would be much appreciated. Thank you! k- -- Kendrick Hernandez *UNIX Systems Administrator* Division of Information Technology University of Maryland, Baltimore County
