[CentOS] ext4, 4k sector alignment

John Doe jdmls at yahoo.com
Tue Jul 26 09:21:58 UTC 2011

From: John R Pierce <pierce at hogranch.com>

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

In my kickstart pre script, I use:
... | sfdisk -H $HEADS -S $SECTORS -uS --force -L $DEVICE
For SSDs, I saw the recommended respective values: 224 56 (or 32 32)
fdisk also has -u for sectors unit, and -H/-S to force a fake geometry.
But, from fdisk man page:
"-b sectorsize
      Specify the sector size of the disk. Valid values are 512, 1024,
      or 2048.  (Recent kernels know the sector size. Use this only on
      old kernels or to override the kernel’s ideas.)"
Which would seem to imply that fdisk is limited to 2K sector sizes?

I do not deal with drives above 2GB though...
But I must admit that I am still a bit confused with all these alignments...


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