Avi Kivity wrote: > Physical block size is the what the logical block size would have been > is software didn't suck. In theory they should be the same, but since > compatibility reaons clamp the logical block size to 512, they have to > differ. A disk may have a physical block size of 4096 and emulate > logical block size of 512 on top of that using read-modify-write. > > Or so I understand it.
I think that's right, but a side effect is that if you get a power failure during the read-modify-write, bytes anywhere in 4096 sector may be incorrect, so journalling (etc.) needs to use 4096 byte blocks for data integrity, even though the drive emulates smaller writes. -- Jamie -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
