Dmedia 13.03 "Copy decreasing"

In this release we'll turn on the copy decreasing behaviours. This means we feel Dmedia is nearly production ready, because this is that scary (but important) feature that could directly cause data loss if Dmedia isn't correct. In contrast, the copy increasing behaviours could at worse fail to prevent data loss.

One way to understand Dmedia is as a smart local file cache. As the user works with different files, this local cache is adjusted to best fit what we anticipate the user will need. As Dmedia is designed for libraries far larger that will fit on a single device, files *must* at times be deleted in order to make room for a different working set.

It is critical that the burden of deciding which files are safe to delete not fall upon the user. This is stressful and exceedingly error prone. We can reduce the chance of data loss here by eliminating human error. But to turn this feature on, we must be very confident that Dmedia is correct.