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From Sudheer Vinukonda <sudhe...@yahoo-inc.com>
Subject Re: partial object caching
Date Thu, 06 Aug 2015 15:43:36 GMT
Background Fetch plugin takes care of that issue for you and won't allow more than one download
for the same object (cache key) at a time. We use that in production (and I think/know a few
other significant deployments do as well) and don't see any issues with fd exhaustion or multiple
downloads for the same file.
The only drawback (if you can call it so) with the solution is that, you may potentially waste
bandwidth/cache space for a really large object which may not be requested by clients often.
Thanks,
Sudheer
 


     On Thursday, August 6, 2015 8:24 AM, Madhava Gaikwad (madgaikw) <madgaikw@cisco.com>
wrote:
   

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Thanks Sudhir for the response. If too many clients starts doing range requests or even a
single client starts sending multiple range requests, using background fetch, may cause multiple
downloads to start, reason being downloads will not be sharable. Keeping rest of the client
connection  idle till, first download completes also not useful as it may cause FD exhaustion
for smaller footprint devices. I may be talking too much without knowing much about implementation
details.    Thank you. Madhava    From: Sudheer Vinukonda [mailto:sudheerv@yahoo-inc.com]
Sent: Thursday, August 06, 2015 8:36 PM
To: users@trafficserver.apache.org
Subject: Re: partial object caching    As of v6.0, ATS does not support Partial object caching
(ala byte range caching).    However, ATS does support returning partial byte range responses
if the whole object is already cached.Background Fetch plugin takes advantage of this fact,
by initiating a full object download in the background on receiving a byte range request for
an object that's not in the cache yet. Once the full object is downloaded and populated into
the cache, subsequent byte range requests are directly served from the cache.       Thanks,
   Sudheer       On Thursday, August 6, 2015 12:34 AM, Madhava Gaikwad (madgaikw) <madgaikw@cisco.com>
wrote:    Hello experts,   I have legacy forward proxy used in enterprise network facing
to internet behind firewall. Unfortunately it cannot do partial object caching. I am looking
if I can get an alternate proxy to do this. My requirement is: 1.      Partial object
caching so updates by apple etc. can be cached. Also video caching will just work. 2.      Streaming
to multiple client at same time should be possible from single server connection.   It seems
varnish can do above stuff. But it works effectively as reverse proxy, so I have to position
it before my proxy, as it cannot work as upstream proxy directly. Also its cache seems gets
vanished after restart(Everything in cache is from heap). Do you guys know if ATS can do this
functionality? I believe it is not possible, but I thought just ask if we achieve this by
any means. A pointing to how to would be really appreciated.     Thank you from Newbie,
Madhava    

  
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