I know of several people who ran software mirroring on Windows and they had major problems with it along the lines that Greg described. I also know some people that never had problems in a similar setup with OpenBSD. Prodded a little more, they never had it crash so I guess sometimes being stable can actually hurt you ... :-)
Johan On 11/29/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > [EMAIL PROTECTED] wrote: > > > >Robbert Haarman writes: > >> Greg, > >> > >> Again, you raise some interesting issues. I > >wonder how likely the > >> catastrophic failures you describe are, versus > >how likely it is that > >> things fail in a way where ccd actually helps > >you. I was hoping someone > >> else would comment on that, but that doesn't seem > >to have happened so > >> far. > > > >When you do a "shutdown -r", has the system ever > >hung on you? Has > >your system ever crashed/paniced/suffered a power > >outage? > > > >How does ccd guarantee that the mirrors are in > >sync? If it can't do > >that, then it's worse than using just a single > >disk, because a fsck > >is only going to look at one half of the mirror, > >and inconsistent > >data on the other half is not going to be touched. > > > > Thankee. Now it makes sense. > It is rather WORSE than you paint. > Once there is ANY discrepancy between the disks, > Murphy's Law is operable and Mother Nature will deal > you its choice of which sector, when. > The disk you update is not the disk fsck'd. > > The system seeming to run properly is no assurance that > it can continue to do so. Disk cache and all that. > > Looks like the only safe way to come up after a power fail > is to break the mirror, fsck, and re-mirror. > > Hardware might know which if any disk had not been updated.
