Extending TTL for Cloud Files CDN Users

Filed in by Megan Wohlford | March 31, 2011 8:27 am

Our users have spoken and we have heard loud and clear! We have extended our limits for TTL (Time to Live) for objects on the content delivery network (CDN)[1].  We have moved our limit up from 72 hours to 50 years.

TTL is a limit that you can set on how long you would like your CDN content to “live” on the CDN edge servers.  Once your TTL expires, the edge server checks back with the origin for a new copy of your object.  If your data rarely changes, you can set a longer TTL so the CDN edge server won’t check back with the origin as often resulting in faster response times for your end users.

That being said, the CDN’s edge servers always operate on the logic that the most popular content will stay cached.  That means if your content is less popular, but you have set a 50 year TTL, it won’t necessarily be 50 years before the edge server has to come back to the origin in Cloud Files for your object.

Simply think of TTL as the longest possible time that your content will go without being updated or requested again from the origin.

While we are changing our upper limits, we will still keep our default of a 72 hour TTL.  That means that if you take no action, your set up will remain exactly as it is today.  If you are using our API, you can now set your TTL anywhere from 15 minutes to 50 years, with increments as low as seconds (e.g. TTL = 26 minutes, 30 seconds).  This feature is coming soon within our Cloud Control Panel and will allow users to set their TTL up to 50 years, in hourly increments.

If you have any questions, comments, or concerns about this feature, please let us know.

Endnotes:
  1. ontent delivery network (CDN): http://www.rackspace.com/cloud/cloud_hosting_products/files/technology/

Source URL: http://www.rackspace.com/blog/extending-ttl-for-cloud-files-cdn-users/