[EMAIL PROTECTED] said: > I took a snapshot of a directory in which I hold PDF files related to math. > I then added a 50MB pdf file from a CD (Oxford Math Reference; I strongly > reccomend this to any math enthusiast) and did "zfs list" to see the size of > the snapshot (sheer curiosity). I don't have compression turned on for this > filesystem. However, it seems that the 50MB PDF took up only 64K. How is > that possible? Is ZFS such a good filesystem, that it shrinks files to a > mere fraction of their size?
If I understand correctly, you were expecting the snapshot to grow in size because you made a change to the current filesystem, right? Since the new file did not exist in the old snapshot, it could never have known about the blocks of data in the new file. The older snapshot only needs to remember blocks that existed at the time of the snapshot and which differ now, e.g. blocks in files which get modified or removed. I would expect that when you add a new file, the only blocks that change would be in the directory node (metadata blocks) which ends up containing the new file. That could indeed be 64k worth of changed blocks. Regards, Marion _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
