[CentOS] ext4, 4k sector alignment

Mon Jul 25 23:35:48 UTC 2011
John R Pierce <pierce at hogranch.com>

On 07/25/11 3:54 PM, Les Mikesell wrote:
>    Device Boot  Start     End      Blocks   Id  System
> /dev/sdh1      1       91201   732572001   fd  Linux raid autodetect
>
> It doesn't need to boot.   And the 3rd member doesn't need to
> autodetect, although I do want to be able to mount it independently if
> needed.   Should it work to use the raw disk instead of a partition?

thats by "cylinder", which is an old MSDOS legacy thing.   I believe 
parted and probably some other programs let you partition by sector instead.

you previously wrote...

On 07/25/11 2:44 PM, Les Mikesell wrote:

> >>  255 heads, 63 sectors/track, 91201 cylinders
> >>  Units = cylinders of 16065 * 512 = 8225280 bytes


so, a 'cylinder' is 8225 kbytes per that.   simply cutting that down by 
a few kbytes will get you on your 4K boundary.   right now a cylinder is 
255*63 = 16065 sectors.  which is most certainly not divisible by 8 (8 
512 byte sectors is 4K bytes)


-- 
john r pierce                            N 37, W 122
santa cruz ca                         mid-left coast