format(1m) should make megabyte-aligned partitions
Most operating systems no longer attempt to use drive geometry when setting partition boundaries, and instead simply make them megabyte-aligned.
This issue proposes make megabyte-aligned partitions the default, and provide an option (-c) to get the old cylinder-aligned behavior.
Man page addition:
-c Cylinder alignment. Make new parti- tions aligned on cylinders, according to the geometry reported by the device, as was common practice long ago. By default, format uses the modern conven- tion of aligning partitions on megabyte boundaries.
Just for history, an earlier proposal was:
-a Align new partitions to 1MB boundaries (default) -A Align new partitions on cylinders, according to the geometry reported by the device, Note that for modern devices that geometry is entirely fictional and can result in partitions that can cause all I/O to be mis-aligned.
Updated by Gordon Ross about 4 years ago
Capturing some email discussion from June 2012 (summarizing)
2949 format(1m) should support megabyte-aligned partitions
Suggests -a / -A and default to megabyte aligned now (-a)
Make -a the default now
Suggests -c for "cylinder alignment"
Josef 'Jeff' Sipek
review comments / suggestions
Would be nice if cmlb did not diverge from the other places that know about this.
(Fixing that may require some more work.)
You can see the email thread on topicbox: