Ciaran McCreesh wrote: > On Sun, 04 Oct 2009 21:53:11 +0200 > Rodolphe Rocca <[email protected]> wrote: >>> or if you don't cleanly power off your computer after >>> unmounting a filesystem, things will break. >> but not this one. >> >> AFAIK when a fs is unmounted, a sync happens on the virtual device and >> the unmount operation is blocking until all data has been flushed to >> the disk (write cache). After what it's up to the hard drive firmware >> to flush the write cache if it is enabled. So normally when unmount >> returns, data is at least in the write cache of the drive. A power off >> during the internal write cache flushing process will trigger data >> loss. Not sure if the reboot will too. > > Unmounting a filesystem doesn't force the disk to really really write > its contents properly. In the general case, there's absolutely nothing > a computer can do to force data to be really really written, whatever > that even means.
That's actually what I said... >> Concerning the merged files I agree that not much more can be done to >> make paludis more resilient to a system crash. >> >> But what about /var/cache/db ? > > Assuming you mean /var/db/pkg... Right sorry. > >> What I'm thinking about is letting paludis work as much as possible >> in a temporary vdb directory and rename this directory in the safest >> possible way once everything is done. > > No point. > >> Next time paludis runs, it could be able to detect inconsistencies and >> automatically fix them. Something like : > > A full VDB scan is slooooow, and might require permissions Paludis > doesn't currently have. That's really not something we want to do. Ok. The scan could be handled by an explicit option (--check-vdb). >> Would it be insane ? > > Yes, it would. > > First, there is absolutely nothing whatsoever that userland software > can do to deal with the user randomly powering off their computer. > > Second, this is a huge amount of effort to avoid something that is > entirely caused by a particularly unpleasant case of user error. Not a user error, a system or hardware error. Anyway I surrender, thanks a lot for your answers, I understand your point of view. _______________________________________________ paludis-user mailing list [email protected] http://lists.pioto.org/mailman/listinfo/paludis-user
