Forum Discussion

Andrea_Arquint's avatar
Andrea_Arquint
Icon for Nimbostratus rankNimbostratus
Nov 03, 2010

troubles with cache dump

Hi

I want see what is in the cache.

So the following link does it but I remark strange behavior with it:

http://devcentral.f5.com/wiki/defau...trace.html

Independently what is configured in my http profiles the irule works sometimes and sometimes not?

When I execute the command:

b http show | grep "RAM cache (entries"

| RAM cache (entries, size, evict) = (15, 53974, 0)

I see hat there are 15 objects are in the ramcache.

But if I execute the iRule I just get the following:

CACHE DUMP

Cache size - 20321 
Cache count- 8 
  Entity - Pos (0008) Local Hits (00000/00000) Remote Hits (00000/00000) Served (027) Age (027) Score (0000) Key - 'www.mydom.net/imgweb/2/V5/misc/arrow_white.gif'
  Entity - Pos (0007) Local Hits (00000/00000) Remote Hits (00000/00000) Served (029) Age (029) Score (0000) Key - 'www.mydom.net/imgweb/2/v4/dyn/btn/Fondue-Raclette-Set_de.jpg'
  Entity - Pos (0006) Local Hits (00000/00000) Remote Hits (00000/00000) Served (029) Age (029) Score (0000) Key - 'www.mydom.net/pages/dynhp/de/hppic_2/3.htmlgzip,deflate,sdch'
  Entity - Pos (0005) Local Hits (00001/00000) Remote Hits (00001/00000) Served (000) Age (981) Score (0004) Key - 'www.mydom.net/favicon.ico'
  Entity - Pos (0004) Local Hits (00000/00000) Remote Hits (00000/00000) Served (1081) Age (1081) Score (0000) Key - 'www.mydom.net/pages/dynhp/de/btn/2.htmlgzip,deflate,sdch'
  Entity - Pos (0003) Local Hits (00000/00000) Remote Hits (00000/00000) Served (1081) Age (1081) Score (0000) Key - 'www.mydom.net/pages/dynhp/de/btn_3/3.htmlgzip,deflate,sdch'
  Entity - Pos (0002) Local Hits (00003/00000) Remote Hits (00003/00000) Served (1129) Age (1133) Score (0000) Key - 'www.mydom.net/ImgWeb/2/V3/mail/channels_de_ms.gif'
  Entity - Pos (0001) Local Hits (00000/00001) Remote Hits (00000/00001) Served (1133) Age (1133) Score (0000) Key - 'www.mydom.net/ImgWeb/2/V3/mail/logo.gif'
Why is that as different as I see???
thx for any help
bb

6 Replies

  • Hi Bigbrother,

     

     

    I wonder if the cache dump run from an iRule returns just that TMM instance's cache and the bigpipe command returns all TMMs' cache info. Are you on a platform and version with two TMM's running by chance?

     

     

    You could open a support case to check on this.

     

     

    Aaron
  • Hi hoolio

     

     

    Yes the platfrom (LTM 6400) has more then one tmm instance as you can see:

     

     

    Nov 4 04:15:39 local/tmm err tmm[4791]: 01010028:3: No members available for pool pool_webserver_test

     

    Nov 4 04:15:39 local/tmm1 err tmm1[4792]: 01010028:3: No members available for pool pool_webserver_test

     

     

     

    Thanx for your answer but the strange behavior is if I clear the ramcache...

     

     

    "bigpipe profile http http_myprofile ramcache entry all delete"

     

     

    ...then I get still the same cache dump trace back even "b http show" tells me that no object is cached???

     

     

    This profile (http_myprofile) is assigned to the virtual server which has also the irule for cache::trace assigned.

     

     

    My only target is to check what is in the cache on the F5 box and what not. If I include or exclude something I want to check if this really happens.

     

    That's why I use this irule. Just to try to find a way to have more transparency on what is going on our LB.

     

     

    What do you think about?

     

     

     

    thanx for help

     

    bb

     

  • Hrm... can you post the iRule you're testing with?

     

     

    Thanks, Aaron
  • Hi hoolio

     

     

     

     

     

    Here is the rule:

     

     

     

    when RULE_INIT {

     

    set static::cache ""

     

    }

     

    when HTTP_REQUEST {

     

    if { [HTTP::uri] ends_with "/aracache" } {

     

    HTTP::respond 200 content "CACHE DUMP\r\n\r\n$static::cache\r\n\r\n"

     

    }

     

    }

     

     

     

    when CACHE_RESPONSE {

     

    CACHE::header insert X-Via F5-LB

     

    set static::cache [CACHE::trace]

     

    }

     

     

     

     

     

     

    This does respond something but if I clear the cache then it still respond the same entries even if they are cleard???

     

     

     

     

     

    Thanx for your help

     

    bb

     

  • Hi BB,

    I think the issue might be the use of a static variable to store the CACHE::trace output. Can you try this example instead to make a request to a URI which ends in /arachache. Until we figure this out, it would be safest to test this on a separate test virtual server.

    
    when HTTP_REQUEST {
    
        Check if request is to our special cache dump URI
       if { [HTTP::uri] ends_with "/aracache" } {
    
           Force this request to be answered from cache
          CACHE::enable
          set cache_trace 1
    
       } else {
          set cache_trace 0      
       }
    }
    when CACHE_RESPONSE {
    
        Check if request was for a cache trace
       if { $cache_trace }{
          HTTP::respond content "Cache trace output:\r\n\r\n[CACHE::trace]\r\n\r\n"
       }
    }
    

    Thanks, Aaron
  • Hi Aaron

     

     

    I tested your iRule like I did before with /aracache but I got a 404 response?

     

     

     

    Thanx for your help