cache manager process - i/o perf

[Maxim Dounin]

Hello!

On Wed, May 21, 2014 at 09:15:16AM -0400, ixos wrote:

> > The "proxy_cache_path" looks corrupted and incomplete. First of
> > all, I would suggest you to make sure you are using "levels"
> > parameter, see http://nginx.org/r/proxy_cache_path.
> 
> I didn't paste all of proxy_cache_path directive. Here you have all.
>     proxy_temp_path /cache/tmp;
>     proxy_cache_path /cache
>         levels=2:2
>         keys_zone=my-cache:20000m
>         max_size=3355443m
>         inactive=7d;

See no obvious problems.

Try looking into system tuning then, your disk subsystem just 
can't cope with load.  There are number of ways to improve disk 
i/o performance, starting from nginx tuning (aio, output_buffers 
etc., see http://nginx.org/r/aio) to OS tuning (in particular, 
tuning vnode cache may be beneficial, not sure how to do this on 
Linux), as well as using a RAID configuration which delivers 
better performance.  A number of recommendations can be found in 
this list, see archives.

An obvious workaround is to reduce disk load by using smaller 
max_size/inactive, and/or with proxy_cache_min_uses (see 
http://nginx.org/r/proxy_cache_min_uses).

> And also nginx version if needed:
> 
> # /usr/local/nginx/sbin/nginx -V
> nginx version: nginx/1.5.9

While it may be a good idea to upgrade to a recent and supported 
version, there shouldn't be a big difference from performance 
point of view.

-- 
Maxim Dounin
http://nginx.org/