On 2015.04.21 09:08, Munir Nassar wrote: > On Tue, Apr 21, 2015 at 7:33 AM, Andrew Berg > <aberg010 at my.hennepintech.edu> wrote: > >> See the zpool-features man page. It varies by feature. Some will completely >> prevent import in this case, while others may simply only make the pool >> read-only. Also, some features are not mandatory at upgrade time and will not >> be enabled automatically. If a feature is disabled, support for it is not >> required for import. > > This is a bit misleading, as the feature would need to have been > disabled from the start. Actually, I was mistaken about features not being enabled automatically. Features are enabled automatically, but are not necessarily active. Any enabled, but not active, features do not prevent import. > > Lets say i create a feature of supercompressor which compresses > everything with my super secret proprietary algorithm(so secret that > even decrypting is a closely held secret), disabling this feature only > affect NEW blocks and old blocks will remain compressed with this > proprietary compressor rendering the pool unimportable by a ZFS > implementation that does not understand the supercompressor feature > flag. A compression feature would always be active, so yes. However, one would be unwise to activate this feature if one planned to ever use it on a system without support for that proprietary feature. As I said, pay attention to which features are going to be activated, and what support other systems have for them.