48 bit LBA question

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Ghostrider

Alon said:
Hello!
I've read that HD's over 137 GB that are being installed in a system that
lacks the supporting BIOS,BUT does the OS's support for large disks (i.e.
Windows XP SP1 or later) can be partitioned as a single partiotion and
accessed by the OS,regardless of BIOS inability to access disks' full
capacity.
Does it mean it's normal and therefore there's no need to upgrade the BIOS
as well?
What's the difference then between the system that has BOTH BIOS and OS
support for large drives and the system that only has OS's support?

Alon
Click to expand...

Not perfectly sure of the question but the limiting factor in
how large a partition can be is determined by the OS and not
the bios that allows large partitions. The example of this is
Windows 2000 where a manual edit of the Windows Registry is
requierd to allow partitions greater than 137 GB. Once this was
done, drive partitions beyond 137 GB in large drives were allowed.
 
You've been doing some funny reading.
If the bios doesnt support large hd's, win wont see the full size.
Some years ago some hd manu supplied utilities/software drivers to enable a
'larger' hd support, but I believe that was in the days of win9* when hd's
were typically 10gb.
In order to have large disk support both the bios and a winnt based o/s must
support it
If the bios supports large hd's (+137) and you install a pre sp winnt based
o/s in that you can only initially format 137gb, then you update win to
include large disk support, thereby Disk Management will see the extra spare
space, and you subsequently partition that spare space, there is a
theoretical possibility of corruption.
 
Hello!
I've read that HD's over 137 GB that are being installed in a system that
lacks the supporting BIOS,BUT does the OS's support for large disks (i.e.
Windows XP SP1 or later) can be partitioned as a single partiotion and
accessed by the OS,regardless of BIOS inability to access disks' full
capacity.
Does it mean it's normal and therefore there's no need to upgrade the BIOS
as well?
What's the difference then between the system that has BOTH BIOS and OS
support for large drives and the system that only has OS's support?

Alon
 
Well the funny reading occurred at this group a few months ago. No digress
or challenging remarks were made by MVPs, or others that frequent with
replies, to that remark made many times here.
I did laugh abit when I read it a few times. Some inconsistencies remain
unchecked here. And may be proliferated by silence.
 
Hello!
I've read that HD's over 137 GB that are being installed in a system that
lacks the supporting BIOS,BUT does the OS's support for large disks (i.e.
Windows XP SP1 or later) can be partitioned as a single partiotion and
accessed by the OS,regardless of BIOS inability to access disks' full
capacity.
Click to expand...

An indication that the BIOS is not critical is seen during
installation of Windows XP:
1. Windows XP CD sans SP1 or SP2 setup program recognizes only 131000
MB of a large disk, even if the BIOS sees the entire disk.
2. Windows XP CD incorporating SP1 or SP2 setup program recognizes the
entire large disk, even if the BIOS does not.
This means the Windows XP setup program does not use the BIOS to
partition and format the disk. You can easily see this for yourself if
you have the appropriate hardware and software.

Once Windows XP is booted and running, the CPU runs in protected mode
and is not able to run BIOS code.
Does it mean it's normal and therefore there's no need to upgrade the BIOS
as well?
Click to expand...

You only need to upgrade the BIOS if the existing BIOS is preventing
you from doing something that the new BIOS would allow.
What's the difference then between the system that has BOTH BIOS and OS
support for large drives and the system that only has OS's support?
Click to expand...

A BIOS that can access large disks allows:
1. booting from a partition that crosses the 137 GB point on the disk
drive.
2. using software that uses the BIOS to access the disk drives to
fully access disks larger than 137 GB (e.g., running Partition Magic
in DOS mode).
 
As a matter of fact,the "funny reading" was from Scott Mueller's book 17th
ed.
I just never heard myself that it's possible to bypass the BIOS,though I
know that XP has direct access to hardware without BIOS's help.So I guess
the same thing happens with large disks recognition.
Though some people here say it's impossible,so I guess the only way is to
try myself ;-)
Though I really don't feel like buying large PATA HD....SATA won't run in
old PC and with SATA-150 PCI card the BIOS issue would be solved to begin
with...Catch-22 :-)
From what I understood until now ,even if OS would see all the large
disk,without BIOS upgrade it can't be a bootable disk (if partitioned as a
single volume)? If so...I don't need a system without BIOS,'cos I like
single partition that is bootable (C:).
I don't think using a Partition Magic is a good idea.Extra headache
+expense.
 
As a matter of fact,the "funny reading" was from Scott Mueller's book 17th
ed.
I just never heard myself that it's possible to bypass the BIOS,though I
know that XP has direct access to hardware without BIOS's help.So I guess
the same thing happens with large disks recognition.
Though some people here say it's impossible,so I guess the only way is to
try myself ;-)
Though I really don't feel like buying large PATA HD....SATA won't run in
old PC and with SATA-150 PCI card the BIOS issue would be solved to begin
with...Catch-22 :-)
From what I understood until now ,even if OS would see all the large
disk,without BIOS upgrade it can't be a bootable disk (if partitioned as a
single volume)? If so...I don't need a system without BIOS,'cos I like
single partition that is bootable (C:).
Click to expand...

A BIOS that has the 137 GB limitation is actually able to boot a
single partition on a 250 GB disk drive. As long as Windows is
installed in an empty partition, the highest point on the disk that
has to be accessed during booting is the NTFS master file table, which
is located at the midpoint (~ 125 GB) of the partition, well below the
limitation.
 
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