Jump to content

2 TiB limit size in MBR hard drives


Cixert

Recommended Posts

On 5/15/2017 at 7:42 PM, dencorso said:

USB HDDs > 2TB do work (there's a thread about that). ATA HDDs don't.
Can you trace the messages path on both and compare?
I don't know how to do it, but I bet it can be done!

The USB HDDs >2TiB that work use 4KiB Sector mapping. I know of no ATA HDD that does.

The message path is still 32Bits so READ(10)/WRITE(10) CDBs are used. 

There are USB HDDs >2TiB that do not use 4KiB Sector mapping. They will not work with XP.
I upgraded the USB and SCSI Drivers to support READ(16)/WRITE(16) to access these Drives in 9x.

Link to comment
Share on other sites


8 hours ago, rloew said:

The USB HDDs >2TiB that work use 4KiB Sector mapping. I know of no ATA HDD that does.

The message path is still 32Bits so READ(10)/WRITE(10) CDBs are used.

Sure! That's why I thought updating the XP SCSI driver to use 4KiB Sector mapping might be the path of lesser resistence, to work on. :)

Link to comment
Share on other sites

5 hours ago, dencorso said:

Sure! That's why I thought updating the XP SCSI driver to use 4KiB Sector mapping might be the path of lesser resistence, to work on. :)

I don't get it :unsure:, there is no issue with "native" 4kb devices (apart from booting) they are just fine as data disks, at least virtually, the whole point revolves around the 32 bit field in the MBR, the LBA is expressed in sectors, the OS recognizes 4kb sectors and (2^32-1)*4096=17592186040320 bytes.

jaclaz

Edited by jaclaz
Link to comment
Share on other sites

No. XP assumes, without checking, 512-byte sectors. That's the issue. But that happens only for the SATA (and presumably also for PATA) HDD. But since 4KiB sectored PATA do not actually exist, so the issue is only reported for SATA. I guess it might also happen for SAS, BTW, for the same reasons, but that's not reported anywhere, AFAIK.

Link to comment
Share on other sites

The XP ATA Driver (PATA and SATA) is hard coded for 512 Byte Sectors. Not sure about AHCI.

Changing it to 4K is not going to help since there are no Drives. Patching the Driver to translate might work. It would be necessary to determine how Sector size is reported to the Driver stack. 

I can Boot DOS and Windows 9x from a 4K Drive but most BIOSes do not support it so I need a 4K emulator DDO.

I have booted DOS using a 32K emulator DDO. It reported 128TiB of Free Space in C:.

Link to comment
Share on other sites

  • dencorso changed the title to 2 TiB limit size in MBR hard drives

@dencorso
@RLoew
Yes , we are all saying the same things :), only slightly differently.


As mentioned in the given thread, the Microsoft VSS drivers (on XP) allow the creation (and mounting and formatting, etc.) of 4 Kb sectored (virtual) disks, this plainly means that the filesystems (at least FAT and NTFS) and related files can work just fine with this sector size, even in the XP implementation.

With "real" disks the issues are in the actual drivers (and the MBR and possibly PBR ) code ASSUMING the 512 bytes size.

I would say that fixing the MBR (and if needed the PBR) code should be if not trivial rather "easy" (and possible) and as well it shouldn't be that much difficult to modify/patch (if needed, haven't really checked) the UNIATA drivers (that do already support the SCSI READ(16)/WRITE(16) commands BTW) .

jaclaz

Edited by jaclaz
Link to comment
Share on other sites

The FAT and NTFS Filesystem Drivers do support 4K Sectors.

The MBR does not care about Sector size. It just uses the first 512 Bytes.

The PBR header has the Sector size encoded in it but doesn't matter otherwise. The associated loader code has to deal with the Sector size as needed.

ATAPI.SYS assumes 512 Byte Sectors and truncates Sector Numbers beyond 32 Bits. Not sure about Read(16)/Write(16).

I will look into UNIATA.

Link to comment
Share on other sites

UNIATA does work as promised. I can access >2TiB through the ASPI Interface. This proves that ATAPI.SYS, even the Windows 2003 SP2 Version does not support READ(16)/WRITE(16).

I still do not have access through \\.\PHYSICALDRIVEx though. I will have to Patch FASTFAT.SYS to see if it can reach UNIATA without truncation.

Link to comment
Share on other sites


@rloew will patching fasfat provide high disk support those who use ntfs ?

Obviously not. Assuming the experiment works, both FASTFAT.SYS and NTFS.SYS and any other File System Drivers would need to be patched.
Link to comment
Share on other sites

Just now, rloew said:


@rloew will patching fasfat provide high disk support those who use ntfs ?

Obviously not. Assuming the experiment works, both FASTFAT.SYS and NTFS.SYS and any other File System Drivers would need to be patched.

But I am missing why they should be patched :unsure: (not for 4Kb sectored drives in themselves, as said the MS VSS driver works fine with (virtual) 4Kb sectored disks under XP and BOTH FAT and NTFS), maybe for larger than 2.2Tb disks which expose a 512 byte sector size?

But then the MBR objective sector number limit would come into play again and you would need GPT. (which BTW can be normally accessed using the existing Paragon loader/driver):

https://www.paragon-software.com/technologies/components/gpt-loader/

which is not free or freeware but all in all - if really needed - is only 20 bucks, and anyway doesn't seem to include any patched (or new) FASTFAT.SYS or NTFS.SYS.

If you want to test the VSS driver, see here:
http://reboot.pro/topic/6492-virtual-storage-driver/

And still noone with an actual >2.2 Tb disk (i.e. the potential users of this) has actually tested the idea in this post:

http://www.msfn.org/board/topic/176480-2-tib-limit-size-in-mbr-hard-drives/?do=findComment&comment=1135913

jaclaz
 

Link to comment
Share on other sites

1 hour ago, jaclaz said:

But I am missing why they should be patched :unsure: (not for 4Kb sectored drives in themselves, as said the MS VSS driver works fine with (virtual) 4Kb sectored disks under XP and BOTH FAT and NTFS), maybe for larger than 2.2Tb disks which expose a 512 byte sector size?

My take is similar: if 4Kb sectored disks (either virtual or actual) do work with both plain-vanilla FASTFAT.SYS and NTFS.SYS, as we know they actually do, at least in the case of WDC My Passaport external USB HDDs, then they oughtn't to require any patching, and perhaps a revised/special version of UNIATA.SYS might be enough to get internal 4Kb sectored disks ATA HDDs working, too, and put within reach the 8 TB limit (when such HDDs become available at reasonable prices, of course). Just my 2¢, of course, and no disrespect to anyone intended.

Link to comment
Share on other sites

11 hours ago, jaclaz said:

But I am missing why they should be patched :unsure: (not for 4Kb sectored drives in themselves, as said the MS VSS driver works fine with (virtual) 4Kb sectored disks under XP and BOTH FAT and NTFS), maybe for larger than 2.2Tb disks which expose a 512 byte sector size?

But then the MBR objective sector number limit would come into play again and you would need GPT. (which BTW can be normally accessed using the existing Paragon loader/driver):

https://www.paragon-software.com/technologies/components/gpt-loader/

which is not free or freeware but all in all - if really needed - is only 20 bucks, and anyway doesn't seem to include any patched (or new) FASTFAT.SYS or NTFS.SYS.

If you want to test the VSS driver, see here:
http://reboot.pro/topic/6492-virtual-storage-driver/

And still noone with an actual >2.2 Tb disk (i.e. the potential users of this) has actually tested the idea in this post:

http://www.msfn.org/board/topic/176480-2-tib-limit-size-in-mbr-hard-drives/?do=findComment&comment=1135913

jaclaz
 

I am referring to 512 Byte Sector Size Disks. Only Windows 9x requires the patch for 4K Sectors. 4K Drives won't be a problem until you exceed 16TiB, which probably won't be too long from now.
I already developed a MBR Extension that is compatible with existing Software and provides 40 Bit Sector Numbers.
I have been using 4TB Bootable Hard Drives with Windows 98SE for years. I am looking into the possibility of extending XP in the same way.

The Paragon Driver appears to be a 4K translator. It would be limited to 16TiB and does not support Boot from the same Drive.

Using translators, I have Booted Windows 98SE from simulated 4K Drives and DOS from a simulated 32K Drive with a 128TiB Partition.

Link to comment
Share on other sites

9 hours ago, rloew said:

I already developed a MBR Extension that is compatible with existing Software and provides 40 Bit Sector Numbers.
I have been using 4TB Bootable Hard Drives with Windows 98SE for years. I am looking into the possibility of extending XP in the same way.

The Paragon Driver appears to be a 4K translator. It would be limited to 16TiB and does not support Boot from the same Drive.

Using translators, I have Booted Windows 98SE from simulated 4K Drives and DOS from a simulated 32K Drive with a 128TiB Partition.

I see. :) Still - with all due respect of course - unless your MBR extension is really-really transparent (and even if it is so) I would personally find more useful a "better than Paragon's" implementation of GPT as this would allow a total interchangeability of the disks (or of their images) on later OS's ( a man can dream ;)).

Also, I believe that little by little the hard disk manufacturers are going to shift largely to 4Kb sectored disks, I doubt that "next generation of >4 Tb disks will be AF, it is more likely that they will be "Native 4k". :dubbio:

jaclaz
 

Link to comment
Share on other sites

My Extended MBR and GPT can be combined. Using my Multi-Boot Profile MBR, they can be used even with systems that do no support Hybrid GPT.

Native 4K Drives, unless provided with a Jumper or other option, are probably years away. I don't know about Internal Drives, but many BIOSes cannot recognize 4K USB Drives.

Patched Windows 98SE will boot from these disks as well as Windows 8 and 10, but XP, Vista, and 7 will not.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...