Re: [squid-users] Re: Squid monitoring, access report shows upto 5 % to 7 % cache usage

On 1/08/2013 6:35 p.m., John Joseph wrote:
> Hi Amos,Ahmad,Babajaga
> Thanks for your advice and feed back, I am posting more information
>
> -------
> the HIT,MISS,REFRESH details are
>
> cat /opt/var/log/squid/access.log | grep -c "HIT"
> 13810283
> cat /opt/var/log/squid/access.log | grep -c "MISS"
> 57874593
> cat /opt/var/log/squid/access.log | grep -c "REFRESH"
> 6760966

Doing a rough calculation here I get just under 18%. Which is low but
inside the 15-40 range normally seen.

> --------
> squidclient info result
>
> squidclient -h 127.0.0.1 mgr:info
> HTTP/1.0 200 OK
> Server: squid/3.1.10
> Mime-Version: 1.0
> Date: Thu, 01 Aug 2013 06:10:06 GMT
> Content-Type: text/plain
> Expires: Thu, 01 Aug 2013 06:10:06 GMT
> Last-Modified: Thu, 01 Aug 2013 06:10:06 GMT
> X-Cache: MISS from proxy
> X-Cache-Lookup: MISS from proxy:3128
> Via: 1.0 proxy (squid/3.1.10)
> Connection: close
>
> Squid Object Cache: Version 3.1.10
> Start Time: Wed, 31 Jul 2013 23:08:41 GMT
> Current Time: Thu, 01 Aug 2013 06:10:06 GMT
> Connection information for squid:
> Number of clients accessing cache: 574
> Number of HTTP requests received: 508778
> Number of ICP messages received: 0
> Number of ICP messages sent: 0
> Number of queued ICP replies: 0
> Number of HTCP messages received: 0
> Number of HTCP messages sent: 0
> Request failure ratio: 0.00
> Average HTTP requests per minute since start: 1207.3
> Average ICP messages per minute since start: 0.0
> Select loop called: 62199585 times, 0.407 ms avg
> Cache information for squid:
> Hits as % of all requests: 5min: 21.6%, 60min: 27.1%
> Hits as % of bytes sent: 5min: 6.6%, 60min: 5.6%

Thank you. This explains the whole story.

MySAR is reporting your cache bandwidth savings HIT ratio (bytes sent).

What you have is a reasonable HIT ratio 21-27% by request count, however
it appears that is built from mostly small objects. The larger objects
are mostly MISS events. Which drags your byte HIT ratio way down low.

However there is more to the story... the log numbers you show above
indicate that about 9% of all requests through your cache are REFRESH,
which may be recorded as a HIT with no byte count associated even on the
largest of objects. With high REFRESH traffic there is also a high
amount of IMS traffic. Those two will drag down the HIT ratio for bytes
down while also being a good thing - the byte count is down because
there actually are less bytes used.
NP: Squid does not yet record how much savings is gained from REFRESH or
IMS traffic, which would help show this a bit better.

> Memory hits as % of hit requests: 5min: 5.6%, 60min: 9.0%
> Disk hits as % of hit requests: 5min: 46.9%, 60min: 47.7%

And the breakdown of where those HITs are coming from shows mostly disk
activity, very little memory benefits.

> MySAR results are
>
>
>
> DATE USERS HOSTS SITES BYTES TRAFFICCache Percent
>
> Thursday, 01 August 2013 11 797 13899 36.11G 4%
> Wednesday, 31 July 2013 42 1024 29862 89.22G 5%
> Tuesday, 30 July 2013 19 1023 27096 85.24G 5%
> Monday, 29 July 2013 29 1022 26425 82.55G 5%

Hmm. These look like your byte-count HIT ratio percentages.

Amos
Received on Thu Aug 01 2013 - 09:33:10 MDT