ram cache problem1

Hi!

Had a discussion with F5 regarding this a few months ago. According to the technician I talked to the LTM performs OR logic to determine if cached entree is subject to revalidation evaluating "maximum age" and cache-control header in server's response. In another words if "maximum age==180" but cache-control: max-age==60", LTM will revalidate the content after 60 seconds.

The cache-control: max-age might not be rewritten by the ltm because it keeps it's own records. You can check the entries by issuing the following command:

show ltm profile ramcache 

You should be able to verify this in the IIS log by checking how often the cached documents are fetched by the load balancer.

/Patrik

Hi Patrik, Thanks for your response. I have an another issue that automate removing cache content on the f5 when app. servers content was changed. Because i dont want to wait until max. age value expiration for the cached object in the web accleration profile so I want to do this process immediately. is it possible wit an irule ?

 

Thanks,

 

Mind that I have not tested this myself and I am currently not in position to do so, but I reckon you can use this method:

https://devcentral.f5.com/wiki/iRules.CACHE__expire.ashx

I imagine you can combine it with a custom header or cookie to set expiration.

Example (not tested or checked for syntax and painfully written on an iphone):

when HTTP_REQUEST {

   if { [HTTP:header exists expirecache] } {
      set cacheexp 1
   }
}

when CACHE_RESPONSE {
  if { [info exists cacheexp] && $cacheexp == 1 } {
    CACHE::expire
  } 
}

Note: If you don't want strangers invalidating your cache you might want to filter by ip as well. 🙂

/Patrik