Two questions...
First, when upgrading to 9.1 presumably it won't auto-update the pool to v5000? You'd have to do it via command line "zpool upgrade -a".
Second, feature flags still confuse the hell out of me. Basically I understand it as allowing different developers to roll out different features independently of each other without versioning consideration. But how would this effect cross compatibility? To me, the beauty of ZFS was that I could just plop an array out of FreeNAS and have it up and running in linux or opensolaris, etc in a matter of minutes. So it seems that if one developer implements a feature flag, let's say LZ4 compression, and you enable it, then if you port to another platform that feature flag may not work any longer and possibly make your pool inaccessible on the new platform??? Would disabling LZ4 on the old platform suddenly make it compatible with v5000 on the new platform??? Also say FreeBSD is implementing their LZ4 feature flag and ZFSonLinux implements their LZ4 feature flag, are they always guaranteed to be cross compatible or are we opening up a jungle of incompatible feature flags?
First, when upgrading to 9.1 presumably it won't auto-update the pool to v5000? You'd have to do it via command line "zpool upgrade -a".
Second, feature flags still confuse the hell out of me. Basically I understand it as allowing different developers to roll out different features independently of each other without versioning consideration. But how would this effect cross compatibility? To me, the beauty of ZFS was that I could just plop an array out of FreeNAS and have it up and running in linux or opensolaris, etc in a matter of minutes. So it seems that if one developer implements a feature flag, let's say LZ4 compression, and you enable it, then if you port to another platform that feature flag may not work any longer and possibly make your pool inaccessible on the new platform??? Would disabling LZ4 on the old platform suddenly make it compatible with v5000 on the new platform??? Also say FreeBSD is implementing their LZ4 feature flag and ZFSonLinux implements their LZ4 feature flag, are they always guaranteed to be cross compatible or are we opening up a jungle of incompatible feature flags?