On 4/27/06, Toby Thain <[EMAIL PROTECTED]> wrote: > Sure ECC would be nice, but how does this differ from disk? Silent > failures are certainly possible. > > The fact that error detection and propagation doesn't really happen > in modern disk subsystems is why systems like Sun's ZFS are coming > into being.
Um. Because *every* cosmic ray hit (of which you can expect one to two every week or so with 2+ gigs of ram) will result in data corruption. It's claimed that disks don't do a great job propagating hard errors, which is true to an extent. But they *do* manage to handle soft errors. Without the coding gain provided by block ECC your modern high density would be nearly useless. ZFS wouldn't make iram seriously useable... because AFAIK, raidz will not work on a single device... so even if can detect a bad block, it can't correct it. The problem goes further than that because the cost of computing block checksums in software will greatly reduce the performance of the fast ram device.. Not that better integrity features are bad.. The iron filesystem paper has a lot of great suggestions that go beyond what ZFS provides, and it would be wonderful to see them in reiser4 someday. But things need to progress one step at a time.
