Re: [squid-users] help with cachemgr statistics

On 30/03/2013 12:48 a.m., Carlos Defoe wrote:
> Hello,
>
> I'm investigating cache manager statistics (60min).
>
> In one sample, i have:
> client_http.requests = 22.785904/sec
> client_http.hits = 6.354478/sec
> client_http.errors = 0.006388/sec
> server.http.requests = 16.956939/sec
> server.http.errors = 0.000000/sec
> aborted_requests = 0.094992/sec
>
> My thoughts:
>
> * client_http.requests means all the http request that arrives to squid;
> * client_http.hits means (approximately) the requests that have been
> completed without using Internet resource, only getting contents from
> the cache;
> * server.http.requests means the requests that are completed making
> access to webservers and downloading content;
>
> So, client_http.hits + server.http.requests =(should be) client_http.requests.
>
> But the result is only approximated (23,31 instead of 22,78).
>
> 1) How can i write a equation that fits "requests -> completions"?
> using those errors and aborted requests? i couldn't figure.

Unfortunately the recorded metrics are a bit rough and you can't write
an equation to calculate that with the existing details. Things are not
as simple as HTTP-in / HTTP-out used to be and the stats counters have
not been kept up with the feature changes very well.

Squid performs translation from non-HTTP server protocols which arrive
as client HTTP requests but leave Squid as FTP or Gopher or TCP tunnels.
Squid also services cachemgr requests and error page embeded content
which arrive as client HTTP requests but never get near being a HIT *or*
MISS.
Squid also performs re-tries on server errors so one client HTTP request
MISS can mean multiple server HTTP requests.

  * on top of all that, Squid accounting is a bit rough around what is a
HIT and how REFRESH are accounted for.

So the best metrics to use are actually the client in/out totals and
server in/out totals for bandwidth. From these you can get a ratio of
bandwidth reduction or indication of problems.

> 2) In another proxy (one very busy, with bad performance),
> client_http.hits + server.http.requests doesn't go near
> client_http.requests:
>
> client_http.requests = 66.597198/sec
> client_http.hits = 8.075425/sec
> client_http.errors = 0.132439/sec
> server.http.requests = 19.327989/sec
> server.http.errors = 0.000000/sec
> aborted_requests = 0.733549/sec
>
> In this case, i think most of the requests (66 - (19+8)) are being
> lost, as this proxy server is in realy bad performance and it's
> hardware is not capable to serve all the requests. But those lost
> requests, where have
> they gone (in statistics)?

Good question. Like to go code diving to find out?

Amos
Received on Fri Mar 29 2013 - 13:27:57 MDT