On Sat, 11 Apr 2009, Jeff Garzik wrote: > > Or just ignore the extra length, thereby excising the 'read-modify' step... > Total storage is halved or worse, but you don't take as much of a performance > hit. Well, the people who want > 4kB sectors usually want _much_ bigger (ie 32kB sectors), and if you end up doing the "just use the first part" thing, you're wasting 7/8ths of the space. Yes, it's doable, and yes, it obviously makes for a simple driver thing, but no, I don't think people will consider it acceptable to lose that much of their effective size of the disk. I suspect people would scream even with a 8kB sector. Treating all writes as read-modify-write cycles on a driver level (and then opportunistically avoiding the read part when you are lucky and see bigger contiguous writes) is likely more acceptable. But it _will_ suck dick from a performance angle, because no regular filesystem will care enough, so even with nicely behaved big writes, the two end-points will have a fairly high chance of requiring a rmw cycle. Even the journaling ones that might have nice logging write behavior tend to have a non-logging part that then will behave badly. Rather few filesystems are _purely_ log-based, and the ones that are tend to have various limitations. Most commonly read performance just sucks. We just merged nilfs2, and I _think_ that one is a pure logging filesystem with just linear writes (within a segment). But I think random read performance (think: loading executables off the disk) is bad. And people tend to really dislike hardware that forces a particular filesystem on them. Guess how big the user base is going to be if you cannot format the device as NTFS, for example? Hint: if a piece of hardware only works well with special filesystems, that piece of hardware won't be a big seller. Modern technology needs big volume to become cheap and relevant. And maybe I'm wrong, and NTFS works fine as-is with sectors >4kB. But let me doubt that. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
