Re: [load balancing] netscaler caching

From: William Bivens <wjbivensIZZATdigitalme.com>
Date: Fri May 20 2005 - 16:35:17 EDT

Actually Justin, Pragma: no-cache is more of a browser control item, in my
opinion it was not designed/intended for reverse or intermediate caching.
Below is good reading URL on the discussion of caching and what does and
does not work...in the mean time I'll have to read up on 2616. :)

http://www.web-caching.com/mnot_tutorial/how.html#PRAGMA

One thing that interests me about Adam's statement is that he's stating that
the Pragma and Cache-Control headers are in the "request" which isn't
something I've seen before...usually they are in the Response from the
server detailing any reverse/intermediate caches or browser caches what they
can/can't keep on disk and for how long.

However I agree with Justin, Cache-Control headers will/should prevent the
NetScaler from caching objects. It used to be (5.2) that you could override
this behavior by doing a "set cache mode -defRules off". This command would
turn off the typical behavior of a cache and ultimately cache everything.
Then you would have to define cache policies on what you don't want to
cache. Please use this command carefully...matter of fact they might of
taken it out of 6.0...I can't remember anymore.

Sincerely,

Jay Bivens

On 5/19/05 1:06 AM, "Justin Barney" <jbarney@netscaler.com> wrote:

> Adam,
>
> If I understand correctly, per RFC 2616, the NetScaler IC behavior is
> correct in that it should not ignore client Pragma and Cache-Control
> headers sent in the request. We honor the client's cache headers by
> default (i.e., if it says no-cache we cause a miss). So I'm not sure
> that it's an issue as much as it is that we are following the RFC.
> Again, I may not be understanding the situation correctly, but this is
> my initial thought.
>
> Justin
>
> -----Original Message-----
> From: owner-lb-l@vegan.net [mailto:owner-lb-l@vegan.net] On Behalf Of
> Adam Denenberg
> Sent: Tuesday, May 17, 2005 7:21 AM
> To: lb-l@vegan.net
> Subject: Re: [load balancing] netscaler caching
>
> sorry if that wasnt clear. Yes we are using integrated caching.
> There is an issue in the 6.47.11 release where the IC does not ignore
> client Pragma and Cache-Control headers sent in the "request".
>
> just wondering if anyone had a workaround, or came across the same
> issue as we did. I have not heard anything back from development
> yet, but they seem to have confirmed this is indeed a known issue.
>
> thanks
> adam
>
>
> On 5/16/05, William Bivens <wjbivens@digitalme.com> wrote:
>> Adam,
>>
>> What's the context?
>>
>> Are you using the NetScaler Integrated Caching?
>>
>> Sincerely,
>>
>> Jay Bivens
>>
>>
>> On 5/16/05 2:28 PM, "Adam Denenberg" <straightflush@gmail.com> wrote:
>>
>>> Hello,
>>>
>>> Has anybody come across the issue of the netscaler not ignoring the
>>> "Pragma: no-cache" or the "Cache-Control: no-cache" header fields.
>>> This is apparently a known bug accroding to development and want to
>>> know if anybody has had to handle this issue.
>>>
>>> The netscaler should be ignoring these fields but its not, and thus
>>> sends extra load to the origin servers. Just wondering if anyone
> has
>>> a workaround or any workarounds on the issue.
>>>
>>> thanks
>>> adam
>>>
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>
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Received on Fri May 20 17:43:33 2005

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