Bob Friesenhahn wrote: > On Tue, 4 Mar 2008, Nathan Kroenert wrote: >> >> It does seem that some of us are getting a little caught up in disks >> and their magnificence in what they write to the platter and read >> back, and overlooking the potential value of a simple (though >> potentially computationally expensive) circus trick, which might, just >> might, make your broken 1TB archive useful again... > > The circus trick can be handled via a user-contributed utility. In > fact, people can compete with their various repair utilities. There are > only 1048576 1-bit permuations to try, and then the various two-bit > permutations can be tried.
That does not sound 'easy', and I consider that ZFS should be... :) and IMO it's something that should really be built in, not attacked with an addon. I had (as did Jeff in his initial response) considered that we only need to actually try to flip 128KB worth of bits once... That many flips means that we in a way 'processing' some 128GB in the worse case when re-generating checksums. Internal to a CPU, depending on Cache Aliasing, competing workloads, threadedness, etc, this could be dramatically variable... something I guess the ZFS team would want to keep out of the 'standard' filesystem operation... hm. :\ >> I don't think it's a good idea for us to assume that it's OK to 'leave >> out' potential goodness for the masses that want to use ZFS in >> non-enterprise environments like laptops / home PC's, or use commodity >> components in conjunction with the Big Stuff... (Like white box PC's >> connected to an EMC or HDS box... ) > > It seems that "goodness for the masses" has not been left out. The > forthcoming ability to request duplicate ZFS blocks is very good news > indeed. We are entering an age where the entry level SATA disk is 1TB > and users have more space than they know what to do with. A little > replication gives these users something useful to do with their new disk > while avoiding the need for unreliable "circus tricks" to recover data. > ZFS goes far beyond MS-DOS's "recover" command (which should have been > called "destroy"). I never have enough space on my laptop... I guess I'm a freak. But - I am sure that we are *both* right for some subsets of ZFS users, and that the more choice we have built into the filesystem, the better. Thanks again for the comments! Nathan. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
