On Wed, Feb 22, 2012 at 09:49:18PM -0500, Mike Snitzer wrote: > Nice write-up. It is concerning that we have to go to such lengths but > I don't see a way around it without limiting who can consume thinp. > > On Wed, Feb 22 2012 at 9:14am -0500, > Joe Thornber <thornber@xxxxxxxxxx> wrote: > > > ** Discards > > > > DISCARDs *must* result in data being zeroed. Some devices set the > > discard_zeroes_data flag. This is not good enough; you cannot use > > this flag as a guarantee that the data no longer exists on the > > disk. So real zeroing must occur. I suggest we write a separate > > target that zeroes data just before discarding it, and stack it > > under the thin-pool. The performance impact of this will be > > significant; to the point that we may wish to turn discard within > > the fs off; instead doing periodic tidy-ups. > > ... > > > ** Summary of work items [0/5] > > > > - [ ] Implement the discard-really-zeroes target [1 month] > > I don't think it'll take a month. Probably a focused week to 2 weeks. By the time you include getting it through agk I think a month is highly optimistic. > I can develop this target before jumping in to the HSM target (unless > you'd rather I start in on HSM asap). HSM is the priority please. ERASE can wait until later. Plus given the development effort and performance impact I think there are other alternatives we should consider (such as using dm-crypt on each thin, and throwing away the keys when you delete it). - Joe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
