On Sun, Jul 14, 2013 at 02:07:41PM +1000, Tim Connors wrote:
Other than the compatibility reason stated there, this FAQ, and the differing behaviour of the scheduling elevator dependent upon whether it's a disk or a partition, has always *smelt* to me.
it's not about whether it's a disk or a partition, it's about the alignment of the partition with a multiple of the sector size. 4K alignment works for both 512-byte sector drives and 4K or "advanced format" drives
If dealing with a whole disk, it still creates -part1 & -part9 anyway.
yep, it creates a GPT partition table so that the data partiton is 4K-aligned. interesting discussion here: https://github.com/zfsonlinux/zfs/issues/94 in theory, zfs could use the raw disk and start at sector 0, but one of the risks there is that careless use of tools like grub-install (or fdisk/gdisk/parted etc) could bugger up your pool....and there's really no good reason not to use a partition table, at worst you lose the first 1MB (2048 x 512 bytes) of each disk.
eh? parted has done proper alignment by default since just after the dinosaurs were wiped out.
it's still quite common for drives to be partitioned so that the first partition starts on sector 63 rather than 2048 - which works fine for 512-byte sectors but not so great for 4K-sector drives. and i know i've spent significant amounts of time in the past, tediously calculating the optimum offsets for partitions to use with mdadm. craig -- craig sanders <cas@taz.net.au> BOFH excuse #424: operation failed because: there is no message for this error (#1014)