>>>>> "Ted" == Ted Ts'o <tytso@xxxxxxx> writes: >> I.e. keep the 512-byte addressing to avoid implementing support for >> 4KB logical blocks in the OS ATA stack. But the drive will reject >> I/Os that are not naturally aligned multiples of 4KB. Ted> It's fine for them to do this; but if they do, they should be Ted> reporting a logical block size of 4k, yes? That's the definition Ted> of what logical block size means.... Kind of, yes. But that involves teaching every ATA driver in $LEGACY_OS about 4KB logical blocks. There is little value is switching to 4KB logical blocks in the first place. So the claim is that it is easier to stick with 512-byte addressing, leave the I/O stack intact, and require the filesystem to always issue aligned units of 4KB. That saves the drive vendors from implementing RMW logic and puts the burden on us. Perfect deal. Ted> Maybe we can create a blacklist of broken drives that report a Ted> logical blocksize of 512 but which really have a logical block size Ted> of 4k? It's not that easy. The logical block size is the unit used when we fill out the commands to send to the device. Using 4KB addressing and issuing block lengths in multiples of 4KB is not what this device wants. *sigh* -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
