All, I'm new to Squid and I have been given the task of optimizing the delivery of photos from our website. We have 1 main active image server which serves up the images to the end user via 2 chained CDNs. We want to drop the middle CDN as it's not performing well and is a waste of money; in it's stead we plan to place a few reverse proxy web accelerators between the primary CDN and our image server. We currently recieve 152 hits/sec on average with about 550hps max to our secondary CDN from cache misses at the Primary. I would like to serve a lot of this content straight from memory to get it out there as fast as possible. I've read around that there are memory and processing limitations in Squid in the magnitude of 2-4GB RAM and 1 core/1 thread, respectively. So, my solution was to run multiple instances, as we don't have the rackspace to scale this out otherwise. I've managed to build a working config of 1:1 squid:origin, but I am having trouble scaling this up and out. Here is what I have attempted to do, maybe someone can point me in the right direction: Current config: User Browser -> Prim CDN -> Sec CDN -> Our Image server @ http port 80 New config idea: User -> Prim CDN -> Squid0 @ http :80 -> round-robin to "parent" squid instances on same machine @ http :81, :82, etc -> Our Image server @ http :80 Squid0's (per diagram above) squid.conf: acl Safe_ports port 80 acl PICS_DOM_COM dstdomain pics.domain.com acl SQUID_PEERS src 127.0.0.1 http_access allow PICS_DOM_COM icp_access allow SQUID_PEERS miss_access allow SQUID_PEERS http_port 80 accel defaultsite=pics.domain.com cache_peer localhost parent 81 3130 name=imgCache1 round-robin proxy-only cache_peer localhost parent 82 3130 name=imgCache2 round-robin proxy-only cache_peer_access imgCache1 allow PICS_DOM_COM cache_peer_access imgCache2 allow PICS_DOM_COM cache_mem 8192 MB maximum_object_size_in_memory 100 KB cache_dir aufs /usr/local/squid0/cache 1024 16 256 -- This one isn't really relevant, as nothing is being cached on this instance (proxy-only) icp_port 3130 visible_hostname pics.domain.com/0 Everything else is per the defaults in squid.conf. "Parent" squids' (from above diagram) squid.conf: acl Safe_ports port 81 acl PICS_DOM_COM dstdomain pics.domain.com acl SQUID_PEERS src 127.0.0.1 http_access allow PICS_DOM_COM icp_access allow SQUID_PEERS miss_access allow SQUID_PEERS http_port 81 accel defaultsite=pics.domain.com cache_peer 192.168.0.223 parent 80 0 no-query originserver name=imgParent cache_peer localhost sibling 82 3130 name=imgCache2 proxy-only cache_peer_access imgParent allow PICS_DOM_COM cache_peer_access imgCache2 allow PICS_DOM_COM cache_mem 8192 MB maximum_object_size_in_memory 100 KB cache_dir aufs /usr/local/squid1/cache 10240 16 256 visible_hostname pics.domain.com/1 icp_port 3130 icp_hit_stale on Everything else per defaults. So, when I run this config and test I see the following happen in the logs: >From "Squid0" I see that it resolves to grab the image from one of it's parent caches. This is great! (some show as "Timeout_first_up_parent" and others as just "first_up_parent") 1237253713.769 62 127.0.0.1 TCP_MISS/200 2544 GET http://pics.domain.com:81/thumbnails/59/78/45673695.jpg - TIMEOUT_FIRST_UP_PARENT/imgParent image/jpeg >From the parent cache that it resolves to, I see that it grabs the image from IT'S parent, originserver (our image server). Subsequent requests are 'TCP_HIT' or mem hit. Great stuff! 1237253713.769 62 127.0.0.1 TCP_MISS/200 2694 GET http://pics.domain.com/thumbnails/59/78/45673695.jpg - FIRST_PARENT_MISS/imgCache1 image/jpeg Problem is, it doesn't round-robin the requests to both of my "parent" squids and you end up with a very 1-sided cache. If I stop the "parent" instance that is resolving the items, the second "parent" doesn't take over either. If I then proceed to restart the "Squid0" instance, it will then direct the requests to the second "parent", but then the first wont recieve any requests. So I know both "parent" configs work, but I must be doing something wrong somewhere, or is this all just a silly idea...? Can anyone comment on the best way to run a high-traffic set of accel cache instances similar to this, or how to fix what i've tried to do? Or another way to put a LOT of data into a squid instance's memory. (We have ~150Million x 2KB images that are randomly requested). I'd like to see different content cached on each instance with little or no overlap with round-robin handling which squid gets to cache an item and icp handling which squid has that item. I'm open to other ideas too.. Sorry for the loooooong email. Thanks all! David __________________________________________________________________ Instant Messaging, free SMS, sharing photos and more... Try the new Yahoo! Canada Messenger at http://ca.beta.messenger.yahoo.com/
