On Mar 11 2007 22:45, Ric Wheeler wrote: > Jan Engelhardt wrote: >> On Mar 11 2007 18:51, Ric Wheeler wrote: >> >> > During the recent IO/FS workshop, we spoke briefly about the >> > coming change to a 4k sector size for disks on linux. If I >> > recall correctly, the general feeling was that the impact was >> > not significant since we already do most file system IO in 4k >> > page sizes and should be fine as long as we partition drives >> > correctly and avoid non-4k aligned partitions. >> > >> >> Sorry about jumping right in, but what about an 'old-style' >> partition table that relies on 512 as a unit? >> >> > I think that the normal case would involve new drives which > would need to be partitioned in 4k aligned partitions. > Shouldn't that work regardless of the unit used in the > partition table? Assume this partition table on my current HD: Disk /dev/hdc: 251.0 GB, 251000193024 bytes 255 heads, 63 sectors/track, 30515 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Start End Blocks Id System /dev/hdc1 1 33 265041 82 Linux swap / Solaris /dev/hdc2 34 30515 244846665 5 Extended That is, 255 * 63 * 30515 * 512 == roughly 251 GB. Now, if this disk was copied byte per byte (/bin/dd) to a 4096-based disk, and Linux would start using a sector size of 4096, then I would suddenly have 255 * 63 * 30515 * 4096 == 2 TB Although I would not mind the 2 TB, the partition table would read quite differently (note the Blocks column which is multiplied by 4 (512x4=4096)) Device Start End Blocks Id System /dev/hdc1 1 33 1060164 82 Linux swap / Solaris /dev/hdc2 34 30515 979386660 5 Extended Which would mean that the swap partition reaches into the real data partition and would corrupt it. That's what I am concerned about. Jan -- - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html