On Thursday 28 June 2001 13:34, Terry wrote:
> From the response I got back from civileme, Linux can only
> recognize a max single drive size of 127 GB. A little bit strange
> that windowz can see a slightly larger hard drive than Linux ...
> hopefully Linux will fix that .. can't have windowz one-upping them
> now, can they? :-)
>
Well, to clarify the situation--There is no one-upping It is an
IDE-ATA hardware limitation at the present time. Moreover the 137G
figure is a trade number--it looks at 137 x 1,000,000,000
My 128G number is 128 x 2^30 which is 128 x 1073741824 or
137438953472
These "trade numbers" are in wide use For example a 20G hard drive
only formats to 18, because the trade number uses the near
equivalence of 2 to the tenth power (1024) and 10 to the third power
(1000) to sloppy things up and make their numbers look bigger than
they really are. One manufacturer even sheepishly pointed out in his
literature that GB (his measurement) meant 1,000,000,000 while Gb
(Hardware Measurement) meant 1073741824.
> Terry
>
> On Wednesday 27 June 2001 21:33, you wrote:
> > You know I saw the same problem and wondered the same thing.
> > Hopefully someone has an answer.
> >
> > On Wednesday 27 June 2001 10:30, Terry wrote:
> > > I was curious ...
> > >
> > > I was watching "The Screensavers" on TechTV last night, when
> > > they aired a segment from the PC Expo in New York City. The
> > > reporter there was talking about a new hard drive from Maxtor
> > > that will hold 100 GB of data. He also mentioned that M$
> > > windows (95, 98, ME, NT, 2000) uses 24-bit addressing, only
> > > allowing windows to recognize a single drive of 137 GB max.
> > >
> > > That made me curious .. what is the largest single drive size
> > > Linux would recognize?
HMMMM
For IDE the same limit applies to BOTH systems, however if you pay
attention during 8.0 install, you will notice something available
called LVM. The size of an LV is ... well see for yourself at....
http://www.linuxhq.com/kernel/v2.2/doc/ide.txt.html for drive limits
for IDE drives
How To Use *Big* ATA/IDE drives with Linux
------------------------------------------
The ATA Interface spec for IDE disk drives allows a total of 28 bits
(8 bits for sector, 16 bits for cylinder, and 4 bits for head) for
addressing
individual disk sectors of 512 bytes each (in "Linear Block Address"
(LBA)
mode, there is still only a total of 28 bits available in the
hardware).
This "limits" the capacity of an IDE drive to no more than 128GB
(Giga-bytes).
All current day IDE drives are somewhat smaller than this upper
limit, and
within a few years, ATAPI disk drives will raise the limit
considerably.
All IDE disk drives "suffer" from a "16-heads" limitation: the
hardware has
only a four bit field for head selection, restricting the number of
"physical"
heads to 16 or less. Since the BIOS usually has a 63 sectors/track
limit,
this means that all IDE drivers larger than 504MB (528Meg) must use a
"physical"
geometry with more than 1024 cylinders.
(1024cyls * 16heads * 63sects * 512bytes/sector) / (1024 * 1024)
== 504MB
(Some BIOSs (and controllers with onboard BIOS) pretend to allow "32"
or "64"
heads per drive (discussed below), but can only do so by playing
games with
the real (hidden) geometry, which is always limited to 16 or fewer
heads).
This presents two problems to most systems:
1. The INT13 interface to the BIOS only allows 10-bits for
cylinder
addresses, giving a limit of 1024cyls for programs which use
it.
2. The physical geometry fields of the disk partition table
only
allow 10-bits for cylinder addresses, giving a similar limit
of 1024
cyls for operating systems that do not use the "sector count"
fields
instead of the physical Cyl/Head/Sect (CHS) geometry fields.
Neither of these limitations affects Linux itself, as it (1) does not
use the
BIOS for disk access, and it (2) is clever enough to use the "sector
count"
fields of the partition table instead of the physical CHS geometry
fields.
......
OK Linux basically has no real limit, and furthernmore, a filesystem
can now be bigger than a single disk. The hardware limitation of the
current mapping scheme for ATA drives applies to Windows and even the
NT and Win2k systems despite their internal addressing ability.
For the mapping of a filesystem to (parts of) multiple disks, see
this:
http://linux.msede.com/ext2/
http://linux.msede.com/ext2/ext2end.html
http://sistina.com/lvm/doc/lvm_howto/index.html
Now since linux sees "sector count", and is capable of ignoring all
the CHS stuff, the question is what size sectors--with physical
sectors of 512 bytes we take the 32-bit unsigned integer which might
be applied to sector count and see that it is 2 to the 31st power K
or 2 to the 21st power M or 2 to the 11th power G, that is 2048G. Of
course if the platform is a 64-bit processor, the limit (within
classical processor arithmetic) is 4 billion times that high. If
sector size is changed (as in the old windows "cluster size" dodge),
then we are limited by imagination and efficiency.
But right now, the trick would be finding a platform that could see a
disk bigger than 128M (IDE Only). One solution is to change the
BIOS, drastically. If you are lucky enough to have a board with an
Intel GX chipset or an SiS 630 or 730 chipset, there IS a BIOS
available which will work wonders on disk size right here.
http://www.acl.lanl.gov/linuxbios/index.html
That wonderful no-limits BIOS? Prepare for a shock, Billy. We call
that BIOS Gnu/Linux! :-) It boots up to framebuffer X in less than
three seconds.
Civileme
