ECS 3.5.0.1 Administration Guide

TSO behavior with the ADO bucket setting turned off

If the Access During Outage (ADO) setting is turned off for a bucket, during a TSO you will only be able to access the data in that bucket if it is owned by an available site. You will not be able to access data in a bucket that is owned by a failed site. By default, the ADO setting is turned off because there is a risk that object data retrieved during a TSO is not the most recent.

In the ECS system example shown in the following figure, Site A is marked as TSO and is unavailable. Site A is the owner of Bucket 1, because that is where the bucket (and the objects within it) was created. At the time Bucket 1 was created, the ADO setting was turned off. The read/write requests for objects in that bucket made by applications connected to Site A will fail. When an application tries to access an object in that bucket from a non-owner site (Site B), the read/write request will also fail. Note that the scenario would be the same if the request was made before the site was officially marked as TSO by the system (which occurs after the heartbeat is lost for a sustained period of time, which is set at 15 minutes by default). In other words, if a read/write request was made from an application connected to Site B within 15 minutes of the power outage, the request would still fail.

The following figure shows a non-owner site that is marked as TSO with the ADO setting turned off for the bucket. When an application tries to access the primary copy at the owner site, the read/write request made to the owner site will be successful. A read/write request made from an application connected to the non-owner site will fail.