On 1/6/15 1:55 PM, Chris Murphy wrote: > What's sectsz= used for? Historically this would be sectsz=512, > bsize=4096 before AF hard drives appeared. So is sectsz used for > optimizing sub blocksize changes? e.g. if only 50 bytes needs > changing, the fs doesn't need to read modify and write the entire 4096 > block, just change the affected sector? Nope, filesystem data blocks are always fully written, but the sector size is i.e. the minimum _log_ IO size. +/* + * The xfs_buftarg contains 2 notions of "sector size" - + * + * 1) The metadata sector size, which is the minimum unit and + * alignment of IO which will be performed by metadata operations. + * 2) The device logical sector size + * + * The first is specified at mkfs time, and is stored on-disk in the + * superblock's sb_sectsize. + * + * The latter is derived from the underlying device, and controls direct IO + * alignment constraints. -Eric _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
