> Sure, if we are ready to restore our data from backup every time there is
> a power failure or OS crash, we can use file systems like tmpfs and ext4
> for these data.
This is a trollish statement. I have lost power and had OS crashes many times with ext4 and never had to restore from backups.
> But many of us want to avoid that hassle in the common
> case when the disk behaves properly, and we need a file system for that
> case that behaves properly, too. And just like IBM (now Hitachi) and
> Maxtor (now Seagate) drives are on my don't-buy list after the problems
> mentioned above, ext4 is on my don't-use list.
Even if you had a filesystem that met all of your requirements (and it's unclear if any real filesystem actually does), no consumer-grade hardware guarantees sane behavior in the event of power loss. Some hard disks are better than others, but a lot have serious problems. Some lie about when data has been flushed to disk. Others corrupt data randomly when power is lost.
Even if you buy only certain brands of drives, manufacturers re-brand hard drives all the time. It's hard to know what you're actually buying.
So *if* your hard drive doesn't ruin power-loss for you anyway, *and* your application is written sloppily enough that it doesn't fsync, *and* this application is critical to your system, then ext3 *might* be more reliable, maybe. Is it possible that you're overreacting?