[CALUG] CALUG Digest, Vol 54, Issue 19

[Walt Smith]

Actually, I'm a little confused.
We have an assortment of information.

As I recall, the numbers of CHS isn't real anymore.  The HD
hides that, although one can pull some number.  

There is the underlying confusion of which each of
CHS starts at 0 or 1.  So when I see CHS which don't add up
in the old classic way, my eyes glaze over and goes
to the next paragraph.


The CHS number may have attained some different meaning 

of status or sector setting for the human installer ?


I do recall generally install selections of 512 bytes or 4096 bytes
had replaced the CHS thingys after drives kept getting irrevokably
bigger.  (Is 4096b/sector still big enough with 3Tbyte drives ?)


However, what can be counted on to be a boundary ?
Is it cylinders, or, it seems implication is on integer sectors.
So certainly bytes can be calculated, but modulo sectors ?
I saw another unfamiliar term in the thread, was it "cycles" ?


I'd really like to ignore anything that says "CHS".


Walt......

=====================================
For backward compatibility, max sectors is 63, heads is 255, in CHS.  So 32/128 
would be 4MiB, not 8MiB, cylinders (and MiB, not GiB).  The maximum 63/255 is 
just under 8MiB, not a perfect boundary.  Many people are using 32/64 for 1MiB, 
although beware of translations that show up.

PC BIOS 16-bit Extended Int13h define most of the legacy structures.  For the 
most part, I just note that things are stored in the first 1MiB (first 2048x512b 
or 256x4KiB sectors) which is considered the MBR.  This has been respected for 
several years now by NT5.1 (XP/2003) and NT6.x (Vista, 7, 2008), so I usually 
just stick with it.

None of this matters with 64-bit uEFI and GPT, of course.

-- Bryan

FYI, Virtually all fixed disks models today are coming with 4KiB sector size.  
Many come with a jumper for 512b emulation that is on by default, but they are 
4KiB.  Until I see universal tool support for 4KiB, I leave the jumper on.  
After all, most everything else is aligned on 4KiB or 8KiB structures anyway, 
and shouldn't be accessing individual 512b bytes.

 
Celebrating over 13,000 emails in my Yahoo Inbox !
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.unknownlamer.org/pipermail/calug/attachments/20110622/1de2a41b/attachment.htm