On Jan 14, 2012, at 6:36 AM, Stefan Ring wrote: > Inspired by the paper "End-to-end Data Integrity for File Systems: A > ZFS Case Study" [1], I've been thinking if it is possible to devise a way, > in which a minimal in-memory data corruption would cause massive data > loss.
For enterprise-class systems, you will find hardware protection such as ECC and other mechanisms all the way up and down the datapath. For example, if you build an ALU, you can add a few transistors to also detect the various failure modes that afflict data flowing through an ALU. This is one of the things that diffentiates a mainframe or SPARC64 processor from a run-of-the-mill PeeCee processor. > I could imagine a scenario where an entire directory branch > drops off the tree structure, for example. Since I know too little > about ZFS's structure, I'm also asking myself if it is possible to > make old snapshots disappear via memory corruption or lose data blocks > to leakage (not containing data, but not marked as available). Sure. If you'd like a fright, read the errata sheet for a modern microprocessor :-) > I'd appreciate it if someone with a good understanding of ZFS's > internals and principles could comment on the possibility of such > scenarios. ZFS does expect that the processor, memory, and I/O systems work to some degree. The only way to get beyond this sort of dependency is to implement a system like we do for avionics. > > [1] http://www.usenix.org/event/fast10/tech/full_papers/zhang.pdf Yes. Netapp has funded those researchers in the past. Looks like a FUD piece to me. Lookout everyone, the memory system you bought from Intel might suck! -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
