On Wed, 9 Jan 2013 02:47:07 +0000 (UTC) Grant Edwards <grant.b.edwa...@gmail.com> wrote:
> > ZFS is designed to deal with this problem by checksumming fs blocks > > continually; it does this at the filesystem level, not at the disk > > firmware level. > > I don't understand. If you're worried about media failure, what good > does checksumming at the file level do when failing media produces > seek/read errors rather than erroneous data? When the media fails, > there is no data to checksum. Not file level - it's filesystem level. It checksums filesystem blocks. And we are not talking about failing media either, we are talking about media corruption. You appear to have conflated them. The data on a medium can corrupt, and it can corrupt silently for a long time. At some point it may deteriorate to where it passes a cusp and then you will get your first visible sign - read failure. You did not see anything that happened prior as it was silent. -- Alan McKinnon alan.mckin...@gmail.com
