>137GB Harddisk support

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JS

I recently installed on my notebook a 160GB hard disk. The BIOS recogniuzes
only 137 GB but XP recognizes all 160GB. I heard of that '137GB boundary'
problem but my notebook is a bit od so there is no longer newer BIOS. Now I
partition this harddisk to only 130GB something and leave the rest 30GB
unused. My question is, in my case, that Xp can see all 160GB but BIOS can
see only 137GB, can I use safely all 160GB in XP? Thanks!
 
JS said:
I recently installed on my notebook a 160GB hard disk. The BIOS
recogniuzes only 137 GB but XP recognizes all 160GB. I heard of
that '137GB boundary' problem but my notebook is a bit od so there
is no longer newer BIOS. Now I partition this harddisk to only
130GB something and leave the rest 30GB unused. My question is, in
my case, that Xp can see all 160GB but BIOS can see only 137GB, can
I use safely all 160GB in XP? Thanks!
Click to expand...

A formatted 160GB hard disk drive (advertised as 160GB) will give you
149.01GB of usable space. That's just the way things work.. I'll give you
a more complete chart/explanation later.

Are you saying that in Windows XP Disk Manager you can SEE all 149 or so GB
of space and you can create a partition/allocate that space and format it as
149GB or so - but in your BIOS - it does not see that?

If your BIOS doesn't *see* the space - it is doubtful that Windows XP should
NOT be able to utilize it all without using some software/boot loader
(usually provided by the hard drive manufacturer) to get around the
limitations of your system BIOS. (AFAIK) In most cases - it is not worth it
to use such a piece of software - in your case - it's not even CLOSE to
being worth it.

Advertised --- Actual Capacity
10GB --- 9.31 GB
20GB --- 18.63 GB
30GB --- 27.94 GB
40GB --- 37.25 GB
60GB --- 55.88 GB
80GB --- 74.51 GB
100GB --- 93.13 GB
120GB --- 111.76 GB
160GB --- 149.01 GB
180GB --- 167.64 GB
200GB --- 186.26 GB
250GB --- 232.83 GB
320GB --- 298.02 GB
400GB --- 372.53 GB
500GB --- 465.66 GB
750GB --- 698.49 GB

The actual formatted and usable storage area is often less than what is
advertised on the boxes of today's hard disks. It's not that the
manufactures are outright lying, instead they are taking advantage of the
fact that there's no standard set for how to describe a drives storage
capacity.

This results from a definitional difference among the terms kilobyte (K),
megabyte (MB), and gigabyte (GB). In short, here we use the base-two
definition favored by most of the computer industry and used within Windows
itself, whereas hard drive vendors favor the base-10 definitions. With the
base-two definition, a kilobyte equals 1,024 (210) bytes; a megabyte totals
1,048,576 (220) bytes, or 1,024 kilobytes; and a gigabyte equals
1,073,741,824 (230) bytes, or 1,024 megabytes. With the base-10 definition
used by storage companies, a kilobyte equals 1,000 bytes, a megabyte equals
1,000,000 bytes, and a gigabyte equals 1,000,000,000 bytes.

Put another way, to a hard drive manufacturer, a drive that holds 6,400,000
bytes of data holds 6.4GB; to software that uses the base-two definition,
the same drive holds 6GB of data, or 6,104MB.

So, be prepared when you format that new 320GB drive and find only 298GB of
usable storage space. Isn't marketing wonderful?
 
I recently installed on my notebook a 160GB hard disk. The BIOS recogniuzes
only 137 GB but XP recognizes all 160GB. I heard of that '137GB boundary'
problem but my notebook is a bit od so there is no longer newer BIOS. Now I
partition this harddisk to only 130GB something and leave the rest 30GB
unused. My question is, in my case, that Xp can see all 160GB but BIOS can
see only 137GB, can I use safely all 160GB in XP? Thanks!
Click to expand...
The function of the BIOS is to configure the hardware and boot the
operating system. Once Windows XP is running it uses its own drivers
to access all hardware, so any hard drive BIOS limitation is of no
consequence except during booting. If your Windows XP CD incorporates
SP1 or 2, then Setup will use an updated atapi.sys driver that
implements 48-bit LBA, which allows the entire disk to be accessed and
partitioned. As long as the midpoint of the partition falls below
137GB, the BIOS will be able to boot from that partition.
 
I know that 1000/1024 rule when calculating disk size. I do not mean that.
My BIOS has only 28-bit addressing so at most sees my disk as a 137GB
(137,000,000,000 bytes) disk, but in XP disk management it sees the full
capacity (160,000,000,000 bytes). Now that I partitioned 137GB, in XP it
sees that there are ~23B unallocated. My question is whether it is safe to
partition that part, as I am afraid it is beyond BIOS's addressing ability
and damage my data (for example, when it goes across FFFFFFF, it returns
back to 0000000, and destroys the track 0 data). I don't know if XP sees
full capacity, it can manage it well.
 
What do you mean 'midpoint' here?
I heard some people say that when they installed XP Sp2 on 160GB disk (on
one big partition), after a period of use Xp cannot boot, because track 0 is
destroyed.
So, besides 48bit LBA in XP, must I also have 48bit LBA in BIOS?
 
For a 160GB disk, the midpoint is 80GB which is where the MFT mirror
is stored.

They're referring to the situation where Windows XP is either repaired
or reinstalled, and it loses its 48-bit LBA capability because the
installation CD is old. Then any access beyond 137GB wraps around to
the beginning of the disk.

No.
 
I heard some people say that when they installed XP Sp2 on 160GB disk (on
one big partition), after a period of use Xp cannot boot, because track 0 is
destroyed.
Click to expand...

After thinking a bit more about this, I think the most likely
situation that results in this problem is:
Someone buys a large disk drive, and using the utilities on the CD
that comes with the drive, he either clones the small drive or
partitions and formats the new drive. In either case the utilities run
under a version of DOS, which means they use BIOS interrupts to access
the disk drives, which in turn means the motherboard BIOS has to
support 48-bit LBA in order for the utilities to fully access the
large disk. However, the time bomb is the cloned Windows or the
Windows XP CD for a new install only supports 28-bit LBA. Over time
the disk fills up, and eventually the 137GB point is reached. The file
system requires 48-bit LBA to store data beyond that point, but the
Windows installation only supports 28-bit LBA, so the data gets
written at the beginning of the disk. The 48-bit LBA motherboard BIOS
won't help you when Windows is running.
 
Thank you very much. So whatever how others get into that trouble, in my
situation, i.e., with 28bit lba bios but 48bit atapi.sys in XP (Sp2), I will
not get into problems and can fully utilize the 160GB disk?
 
Thank you very much. So whatever how others get into that trouble, in my
situation, i.e., with 28bit lba bios but 48bit atapi.sys in XP (Sp2), I will
not get into problems and can fully utilize the 160GB disk?
Yes.
Click to expand...
 
In my notebook bios I can choose to encrypt my harddisk so that when it is
removed from my notebook, it cannot be read elsewhere. I had tried it before
with smaller disks and it worked very well. The encryption/decryption is a
very quick process (just a few seconds) so I guess it just sets or wraps
something somewhere on the hard disk. Now as the BIOS cannot recognize my
full disk, is it still safe to encrypt it in BIOS?
 
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