On Mon, 2015-09-28 at 23:16 +0000, Hugo Mills wrote: > On Mon, Sep 28, 2015 at 07:11:51PM -0400, Calvin Walton wrote:
> > > > The problem with trying to use btrfs checksums to compare two > > different > > files is that the blocks might not match up, if only due to > > fragmentation. E.g., the same 1gb file might be stored like this on > > one > > machine: > > > > [ 256MB ][ 512 MB ][ 256MB ] > > > > And like this on the other: > > [ 512MB ][ 512MB ] > > > > Since the checksums are per block, and the blocks can be different > > arrangements on different machines, they're not really all that > > useful > > for doing comparisons like you want. > > No, those are extents, not blocks, and the FS doesn't checksum in > extents. :) Blocks are 4 KiB in size. Oh, wow, btrfs is storing a lot more checksums than I thought it was... Thanks for clearing up my misconception. -- Calvin Walton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
