On Tue, November 3, 2009 15:06, Cyril Plisko wrote: > On Tue, Nov 3, 2009 at 10:54 PM, Nils Goroll <sl...@schokola.de> wrote:
>> But: Isn't there an implicit expectation for a space guarantee >> associated >> with a dataset? In other words, if a dataset has 1GB of data, isn't it >> natural to expect to be able to overwrite that space with other data? >> One > > I'd say that expectation is not [always] valid. Assume you have a > dataset of 1GB of data and the pool free space is 200 MB. You are > cloning that dataset and trying to overwrite the data on the cloned > dataset. You will hit "no more space left on device" pretty soon. > Wonders of virtualization :) Yes, and the same is true potentially with compression as well; if the old data blocks are actually deleted and freed up (meaning no snapshots or other things keeping them around), the new data still may not fit in those blocks due to differing compression based on what the data actually is. So that's a bit of assumption we're just going to have to get over making in general. No point in trying to preserve a naive mental model that simply can't stand up to reality. -- David Dyer-Bennet, d...@dd-b.net; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
