Yum, Proxy Cache Safety, Storage Backend

[chasd]

Les Mikesell wrote:

> I'm missing something here.  A cache is only going to resend what  
> it got
> the first time.  If the first user got the right thing, so will the
> second.  If the first user got something wrong, don't blame the cache
> for it.


There can be a problem when the cache holds on to the "bad" data for  
too long, serving that to other clients that ask for it later. The  
way things are now, a cache has a good reason _not_ to look for fresh  
data when the end users would like it to. In that case, some blame is  
on the cache, and every once in a while I have to kick squid in the  
butt because of that. Adjusting the tools used to update machines and  
to create the repos in order to help the cache make better decisions  
is a Good Thing.

General comments about this thread :
The default update scheme is to use multiple mirrors managed by an  
intelligent script. Works for a lot of people, but not everyone.
I think there needs to be an assumption that some kind of  
administrator is going to have to opt out of that default and opt  
into any caching scheme. At that point the issue is how easy do we  
make it for the administrator to do that ? What kind of changes need  
to be made on the clients, and what additional infrastructure changes  
need to be made ?

Instant Mirror is very easy right now, at least if you have any chops  
as an admin. Install a rpm, twiddle the config, set up a host in DNS,  
distribute a repo file for the clients. My view on the intent of Mr.  
Togami's OP is to accept that level of ease-a-tude-inosity and make  
the solution less error prone. Making the opt-in easier would only be  
a bonus.

The way I use and configure squid for general web access caching  
would not make it a good cache for updates. I would rather have a  
separate update caching mechanism rather than try to make our squid  
cache do double duty. I would want more control over that update  
cache than whatever squid would supply automatically.


Charles Dostale