[CentOS] Stripe vs Cylinder alignement...

John Doe jdmls at yahoo.com
Fri Oct 30 15:45:59 UTC 2009


Hi,

I modified my kickstart to do some custom partioning and formating in a pre-install script.
I am trying to align the partitions on the RAID stripe (and format with a correct stride).
But, sfdisk complains that it does not start/end on a cylinder boundary (used -L option to limit complaining).
Since the cylinder size is not a multiple of the stripe size, I cannot align on both.
I tried to align the begining on the stripe and the end on the end of a cylinder, but sfdisk still compains...
Basicaly, I have a 128KB (256 sectors) stripe, and 255*32 = 8160 sectors cylinders.
What I am doing is:
begin = ( begin / 256 ) * 256
end = ( end / 8160 ) * 8160 -1
So, for my first partition (96MB):
  begin=256
  size = ( ( 96 * 1024 * 2 ) / 8160 ) * 8160 = 195840 sectors
  end = 195840 - 1 - 256 = 195583
Any idea what I am doing wrong in my calculations or logic?

Thx,
JD


      


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