On Fri, Mar 2, 2012 at 6:11 PM, Ted Ts'o <tytso@xxxxxxx> wrote: > I'm even aware of one implementation which remembers the trim > request while the system is powered on, but since it doesn't > (necessarily) write the trim information to stable store, you could > trim the block, read the block and get zeros, then take a power > failure, and afterwards, read the block and get the previous contents. > > As far as I know, the Trim spec allows all of this. It's been a while since I read the spec, but the read operation above changes the rules I believe. That is if the SSD advertizes itself as having deterministic reads after a trim, that read should lock in the values, and a power cycle should not change that as I understood the spec. Otherwise what you describe would be a non-deterministic read. That is also allowed, but the drive would need to advertise itself as non-deterministic after trim. Greg -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
