large HD partition: who is right?

  • Thread starter Thread starter ML
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ML

My P3 MB cannot support > 130GB HD (no more BIOS update) and i want to use a
500GB HD.
I was told that XP SP2 has LBA48 bit support built in it and should be able
to see the 500GB partition, even if BIOS does not have LBA48 bit. XP scans
the bus and ignoring the BIOS.

While checking online, I came across posts which said that in order to use
the whole 500GB partition, both BIOS and OS must have LBA48 bit support.

Now, who is right? Do I need both to work?
If i could get it to work with just XP SP2, I would be very happy.
If not, I need to buy ATA133 PCI card to connect HD and break the 130GB
barrier, right?

Thank you in advance for answering my post!
 
ML said:
My P3 MB cannot support > 130GB HD (no more BIOS update) and i want
to use a 500GB HD.
I was told that XP SP2 has LBA48 bit support built in it and should
be able to see the 500GB partition, even if BIOS does not have
LBA48 bit. XP scans the bus and ignoring the BIOS.

While checking online, I came across posts which said that in order
to use the whole 500GB partition, both BIOS and OS must have LBA48
bit support.

Now, who is right? Do I need both to work?
If i could get it to work with just XP SP2, I would be very happy.
If not, I need to buy ATA133 PCI card to connect HD and break the
130GB barrier, right?

Thank you in advance for answering my post!
Click to expand...

In *most* cases - if your hardware cannot do it - it does not matter what
your software can do.

There is software made to bypass/get around the hardware limitations (I
believe they used to be called overlays - they acted as a mediator between
the hardware and the software and allowed the two to overcome lacking
hardware. I do not recommend that.)

I believe you would be wasting your money investing further in this P3
system. Getting a 500GB hard disk drive and a controller for obsolete
hardware seems a waste of money and time when inexpensive computer systems
that come with large amounts of hard disk drive space, faster processor,
likely more of everything can be had for $500 or less - in some cases $199
or less. My suggestion - look into "barebone" type systems. You'll be
happier for much longer.
 
Both Bios & o/s need to support large disks, if bios dosnt support and you
manage to install then corruption could occur.
Rather than a PCI card, a better option might be to upgrade the motherboard,
as if it that old that the bios doesnt support large disks, there are likely
to be further bottlenecks in its components.
 
With regard to my problem, I'm thinking of adding a 2nd HD like below:
If I were to use an external USB 500GB HD, would I be able to format this
HD using XP with SP3 > Computer Management > Disk Management as 1 big
partition?
Is this approach still limited by the Motherboard's BIOS problem?
Would the OS able to "see" the whole HD after formating?

Anything to look out for when buying USB2 external enclosure for the 2nd
500GB HD or should I buy the complete set from maker like seagate?

thank you again!!!
 
ML said:
With regard to my problem, I'm thinking of adding a 2nd HD like
below: If I were to use an external USB 500GB HD, would I be able
to format this HD using XP with SP3 > Computer Management > Disk
Management as 1 big partition?
Is this approach still limited by the Motherboard's BIOS problem?
Would the OS able to "see" the whole HD after formating?

Anything to look out for when buying USB2 external enclosure for
the 2nd 500GB HD or should I buy the complete set from maker like
seagate?
Click to expand...

USB should work fine.
Format it NTFS if you plan on having files over 2GB in size.
Format it (leave it default formatted) if you need it to go to different
machines like a Macintosh, etc.
Seagate or Western Digitals would be a good bet - Seagate has the better
warranty.
 
Using any large disk on a bios that doesnt support large disks leaves you
open to data loss / corruption
If you can afford a 500gb external you can afford a new mobo
 
My P3 MB cannot support > 130GB HD (no more BIOS update) and i want to use a
500GB HD.
I was told that XP SP2 has LBA48 bit support built in it and should be able
to see the 500GB partition, even if BIOS does not have LBA48 bit. XP scans
the bus and ignoring the BIOS.

While checking online, I came across posts which said that in order to use
the whole 500GB partition, both BIOS and OS must have LBA48 bit support.

Now, who is right? Do I need both to work?
If i could get it to work with just XP SP2, I would be very happy.
If not, I need to buy ATA133 PCI card to connect HD and break the 130GB
barrier, right?

Thank you in advance for answering my post!
Click to expand...
 
The only time the BIOS comes into play is during the boot process. If
the BIOS has to access past the 137 GB point on the disk in order to
boot Windows XP, then booting will fail. Once Windows XP starts to
run, the CPU is switched to protected mode, and real mode BIOS code
can no longer be executed.

If the 500 GB is installed as a second non-bootable drive, then
Windows XP SP2 will be able to fully access the drive. If Windows XP
is installed on a small partition below the 137 GB point on the 500 GB
drive, Windows XP SP2 will be able to access the rest of the drive in
a second partition.
 
Not according to a tech post I read, sometime ago, which stated there was a
theoretical posibility of disk/file corruption.
Personally I would'nt be prepared to run the risk, and with mobo prices
there is no need to do so
 
Andy's explanation is exactly right. Real mode and protected mode require
different device drivers. The BIOS provides only a real mode driver. Once
XP-SP2 kicks into protected mode and replaces the device driver with its own
protected mode driver, the BIOS driver is out of the loop. The trick is
getting it to boot in the first place so it gets to that point. That's the
reason for keeping the OS partition entirely within the lower 137GB.

The "theoretical possibility of disk/file corruption" comes into play if you
use any utility that attempts to access the disk using the BIOS's real mode
driver, so you have to be careful what tools you use. Windows' native
functions won't do that, so as long as the upper part of the disk is only
accessed by Windows, you'll be okay.
 
Dear friends

Thank you for all the inputs to this post.
The reason I'm keeping my P3 is I do not need something better, I just want
a larger HD storage space.

Thus, I'm keeping my existing 30GB HD with XP SP3. Will either add an
external or internal slave HD of 500GB, and use XP to partition the whole HD.

Regarding the "utility that attempts to access the disk using the BIOS's
real mode driver" that might cause file corruption. Could you explain more.
Do 3rd party tools like those disk defrag software for windows come under
this?

Thanks.
 
This is one area where it isn't worth taking risks, because of the issue of
sudden and catastrophic data loss if you get it wrong. If the system as a
whole isn't large-disk compatible, an IDE disk will work until 137GB full,
and then instantly nuke everything on the disk as the addressing wraps-around
and the MBR (track 0) is over-written.

Windows' disk manager is intelligent enough (even in NT4) that if it spots a
likely address-wraparound situation it will generally not let you create
partitions above 137GB. But, there are of course ways of circumventing that,
and Windows will not complain about a disk which is already partitioned and
formatted by external software.

If you are at all in doubt about this you need to test by filling the disk
past this point. (or just creating a partition in the 130-150GB region and
filling this) Since this is a laborious process it's easier just not to take
the chance.

BTW, partitioning the disk into two will not solve the problem, it's the
total cluster-count that's the issue. Though, you can accept that space above
137GB must not be used. On a 500 that's a rather large sacrifice, though,
 
In general, anything designed to stay in Windows should be okay. Your aim
is to control when/where the BIOS's 137GB-hindered real mode driver gets
used, and you can't use real mode drivers while in Windows because Windows
switches the CPU into protected mode.

What you have to be careful of is using non-Windows programs (old Ghost
versions, for example) because those will almost always use the BIOS driver
for compatibility. Don't be fooled by programs like the venerable Partition
Magic, which is actually a DOS-based program. It may look like it installs
in Windows but in operation it reboots to DOS and then back into Windows.
 
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