[CentOS] SiL311x SataRaid (sata_sil)

Bryan J. Smith

b.j.smith at ieee.org
Sat Jun 18 16:30:10 UTC 2005


On Sat, 2005-06-18 at 11:56 -0400, William Warren wrote:
> not necessarily.  I had a friend put linux on his computer but 
> his bios doe snot support 48 bit LBA so he only saw 30 gigs both 
> in the bios and in linux itself.

Check the jumpers on the disk.  Some have an option to limit the
number of heads reported to 16 (not 255) and/or cylinders to 1024.  That
would cause an issue.

BTW, the ATA28 (28-bit) limitation is _not_ 33.8GB (32GiB), it's:

  16,384 cylinders (14-bit)
      63 sectors/cylinder (6-bit)
     255 heads (8-bit)
     512 bytes/sector 
 ========
   137GB (128GiB) (14-bit + 6-bit + 8-bit = 28-bit)

Now if you're limiting heads to 16 (instead of 255), that can cause the
limitation by which the maximum number of cylinders is 65,536 (16-bit)
because some OSes have a limitation on the number of cylinders in their
geometry.

  65,536 cylinders (16-bit)
      63 sectors/cylinder (6-bit)
      16 heads (5-bit, 10000, instead of all 1s)
     512 bytes/sector
 ========
    33.8GB (32GiB)

That's a common issue cause by the disk being jumpered to report only 16
heads.


-- 
Bryan J. Smith                                     b.j.smith at ieee.org 
--------------------------------------------------------------------- 
It is mathematically impossible for someone who makes more than you
to be anything but richer than you.  Any tax rate that penalizes them
will also penalize you similarly (to those below you, and then below
them).  Linear algebra, let alone differential calculus or even ele-
mentary concepts of limits, is mutually exclusive with US journalism.
So forget even attempting to explain how tax cuts work.  ;->





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