On Sunday 31 July 2011 14:15:20 Joshua Murphy wrote: > Well, GParted, if I recall, does a couple checks to guess 'best' block > size when cloning or moving a partition, but I'm really not sure how > it does things when shrinking and shifting it sideways to a spot that > overlaps with where it started... but based on the above, I would > guess it really does do a bs of 512, or ar best, the cluster size of > the file system it is moving (usually 4k), since it's moving the data > stored there, not the whole partition, block for block.
In fact it did run those tests, and it settled on a value of, I think, 16MB blocks. It then ran a read-only test of the entire file system, and only then started copying it. As it was moving the partition upwards by about half its occupied size, there was considerable overlap. That must mean that it started with the highest-numbered block and worked steadily (very!) downwards. I don't know where in the partition it ran its speed tests, but on a partition that occupies almost all the physical disk, as it did, there must be a considerable speed difference between its two ends. -- Rgds Peter Linux Counter 5290, 1994-04-23
