28-Bit LBA 137.4 GB Hard Drive Size Limit--Does This Affect Only Windows XP's System Partition OR Both the System & Boot Partitions?
On an older system that only supports 28-bit Logical Block Addressing (LBA) (only sees hard drives of 137.4 GB or smaller) and not 48-bit LBA, can I overcome this limitation by formatting a small Windows XP system partition (C:\), perhaps 50 MB or less and creating a second partition (D:\), the boot partition and installing Windows on this boot partition? Another option would be to format the system partition near the 137.4 GB limit; however, I would prefer to have all of my files, with the exception of the system partition files (ntldr, boot.ini, ntdetect), on one partition, as if it were a single C:\ partition. Also, if I do not plan to dual-boot the system, is 50 MB too large of a system partition or will additional files be placed on this partition, with normal use of the system? What would be an appropriate size for such an XP system partition? I have been using this system for years; however, now that I have acquired a lot of data, I started getting the dreaded "disk read error occurred" message and I have linked it to the 28-bit LBA limitation. So, I am wondering if I can overcome this by simply creating a small XP system partition and a large XP boot partition (for D:\Windows directories, data directories, etc.), as I do NOT want to rebuild my system, only to see this "disk read error" message, again. Thank you for your assistance. I look forward to everyone's help. Thank you.
October 8th, 2010 5:59pm

On Fri, 8 Oct 2010 21:54:16 +0000, Voltron-IU wrote:On an older system that only supports 28-bit Logical Block Addressing (LBA)(only sees hard drives of 137.4 GB or smaller) and not 48-bit LBA, can Iovercome this limitation by formatting a small Windows XP/system/ partitionNo, it's not Windows that only sees partitions up to 137GB, it's theBIOS that only sees physical hard drives up to 137GB. (But see pointnumber 2 below, for the Windows involvement).You need two things to support a drive that large:1. A motherboard with a BIOS and controller that supports 48-bit LBA(or alternatively, an add-in controller card that does).2. At least SP1 of Windows XP.Ken Blake (MS MVP)
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October 8th, 2010 6:22pm

Hello, Ken:Thank you for your quick response. I am aware of the points you addressed. My motherboard does not support 48-bit LBA, it only supports 28-bit, which is why my BIOS only sees 137.4 GB of my hard drive. I am using Windows XP Professional, with Service Pack 3. I am not able to use an add-on controller card; so, from my research, it would appear that if I create a system partition that is within the 137.4 GB range of the motherboard BIOS, the BIOS will be able to see the system partition hardware-related files, i.e., boot.ini, ntldr, ntdetect and will be able to transfer the rest of the boot process to the boot partition, the partition where the \Windows files are installed, allowing the system to start up, properly, without seeing the dreated "disk read error occurred." From what I have been able to find out, this is all the BIOS needs and once it transfers the boot process over to the boot partition, it is up to Windows XP to finish the boot process, which, I believe, has nothing to do with the BIOS and should not be affected by the 28-bit LBA limitation. I am wondering if this is correct. Whether this is correct or not, will determine my partition scheme for my system rebuild.I know that most people will not separate their system and boot partitions, but, this is the heart of my question. Since XP does allow the separation of the system and boot partition, can I simply create a small system partition (C:\), perhaps only 50 MB or so, which will be well within the 137.4 GB range of the BIOS and use the rest of my 250 GB hard drive for my XP boot partition for the D:\Windows directories and data files, as if this drive were one big "C:" drive, as it was before. I want to keep things simple and have all of my files on one partition, if I can, without splitting the drive into two equal-sized partitions.I hope I am making sense; I sincerely appreciate your help. Thank you, Ken and everyone else.
October 8th, 2010 6:46pm

Some time ago it was reported, in circumstances such as yours, that there was a theoretical posibility of data loss / corruption if a large disk was used with the o/s installed on a small partition, then another partition created from the resulting drive space.Its also the case that emulation software that enables a large disk to be used when the bios doesnt support it can lead to problems.Your hw must be very old, and you could be said to be living on borrowed time. I trust you have verified data backups.
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October 8th, 2010 7:30pm

Hello, Palcouk:Thank you for your response. I have also read these Microsoft documents. My research is leading me to believe that if I separate the system partition on a small partition (C:\) and install the boot partition or the partition with the Windows XP system files on the remaining hard drive space, for example on the D:\ partition, things may be fine. My research has led me to believe that if I installed both the system and boot partitions on the C:\ partition that is at 137.4 GB or smaller, everything will be fine, as the OS will not have a problem seeing the remaining hard drive space, i.e., D:\ and the system BIOS will not have any problems booting the system, as the system partition will be enclosed within the primary partition that is partitioned within the 137.4 GB barrier. The 28-bit LBA limitation seems to be a pain during the bootup process and not after XP loads, since I am using Service Pack 3. But, as you can tell, I am not certain and I would like to be. :) Thanks, again.
October 8th, 2010 7:50pm

The docs state quite clearly that there is a theoretical possibility of data loss in a system such as yours, if you configure it as you have indicated.I say again, if you proceed, ensure your backups are current
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October 9th, 2010 8:49am

Hello:In this circumstance, do others believe that if one partitions such a hard drive into partitions that are less than 137.4 GB in size, that this will keep one from having any 28-bit limitation-based issues, as the older motherboard should be able to see the entire system and boot partitions, even if they are separated?
October 11th, 2010 7:04pm

IDE hard drives run less than 50.00,simply install a 2nd drive for all youre misc.
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October 11th, 2010 7:55pm

The answer has been posted several times, the tech article clearly states there is a theoretical possibility of data corruption, and there is no workaround for that if using a disk larger than 137gb, whether or not you partition a large disk into blocks of less than 137gb
October 12th, 2010 10:56am

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