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oc_dt

Using big USB HDDs with Win 9x/ME

27 posts in this topic

There are some messages regarding USB and 137GB limit. However, I'm still not sure about the limitation.

I have this USB driver (Maximus-Decim Native USB driver) installed, are there any disk size limit? After plugging in a USB storage, should that be FAT32 by default?

My concept is still not quite clear.

Edited by oc_dt
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There are some messages regarding USB and 137GB limit.
There is no 137GB limit for NUSB. There is no 137GB limit for USB. Period. I'm positive about this.
I have this USB driver installed, are there any disk size limit?
The only limits are those due to the FAT filesystem and to VFAT.VxD (see next answer).
After plugging in a USB storage, should that be FAT32 by default?
It can be FAT-12 (up to 32 MiB, due to the maximum number of sectors allowed in the boot record), FAT-16 (up to 2 GiB due to the FAT having 16 bits) or FAT-32 (up to 1 TiB, due to limitations in VFAT.VxD). It cannot be NTFS or any other FS, unless you add the corresponding third party FS driver.

HTH

Edited by dencorso
Corrected a horrible GiB for TiB typo. Thanks a lot for the heads up BenoitRen!
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There are some messages regarding USB and 137GB limit.
There is no 137GB limit for NUSB. There is no 137GB limit for USB. Period. I'm positive about this.
I have this USB driver installed, are there any disk size limit?
The only limits are those due to the FAT filesystem and to VFAT.VxD (see next answer).
After plugging in a USB storage, should that be FAT32 by default?
It can be FAT-12 (up to 32 MiB, due to the maximum number of sectors allowed in the boot record), FAT-16 (up to 2GiB due to the FAT having 16 bits) or FAT-32 (up to 1 TiB 1GiB, due to limitations in VFAT.VxD). It cannot be NTFS or any other FS, unless you add the corresponding third party FS driver.

HTH

Thanks for your prompt response. However, I'm still confused:

For NUSB, are you referring to Maximus-Decim Native USB?

Isn't FAT-32 supporting storage of 8 terabytes?

Filesize limitation doesn't bother me yet. I just want to recognize a USB harddisk of 500 GB. I have Maximus-Decim Native USB driver installed under Win98SE, what should I do? Please kindly redirect me to the appropriate thread, if this topic were discussed before.

Thanks once again.

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For NUSB, are you referring to Maximus-Decim Native USB?
Yes. Findable in Maximus-Decim Native USB Drivers, post #1, and also here: Windows 98 USB Mass Storage Device Drivers.
Isn't FAT-32 supporting storage of 8 terabytes?
It's complicated... FAT-32 uses 28 bits (not 32, mind you), so, yes, that allows for a maximum of 8 TiB... but the system is not just the FAT, there is, at least, also the volume boot record (= VBR a.k.a. partition boot record = PBR), and that structure has a 32-bit field for storing the total number of sectors of the partition, which results in a limit of 2 TiB. Now, that's the true limit of the FAT-32 filesystem, as you can check in the File Allocation Table entry in the Wikipedia, for more details. But, last year, RLoew found out that the VFAT.VxD (which is Win 9x/ME's protected mode filesystem driver) has a flaw that efectively prevents it from working correctly above 1 TiB (and developed a patch to resolve this issue, see the section "PRERELEASE AND BETA SOFTWARE" of RLoew's Homepage). So, to make short a long story, the effective limit of FAT-32, when used under Win 9x/ME is 1 TiB, unless you patch VFAT.VxD. Incidentally, RLoew has other patches relevant here, that permit one to go up to the 8 TiB, but then one will be using a non-standard FAT-32.
Filesize limitation doesn't bother me yet.
We're *not* talking about that! We're here talking about FileSystemSize, mind you. The Filesize limit for FAT is 4 GiB - 1 byte or the maximum FileSystemSize, whichever is less. That amouts to 32 MiB for FAT-12, 2 GiB for FAT-16 and, for FAT-32, 4 GiB - 1 byte. That is so because the directory entries in FAT store the Filesize as a 32-bit number.
I just want to recognize a USB harddisk of 500 GB. I have Maximus-Decim Native USB driver installed under Win98SE, what should I do?
Plug in the USB HDD. It'll just work! :thumbup Mind you that it takes about 30 sec or a little more to detect and mount so big a HDD. It's not a bug, though. And Win XP Pro SP3 takes just as long. Yet, a single 500 GiB partition works, but is not a good idea, because many of the usual maintenance tools cannot cope well with that. I have one such USB HDD for some years, now, and decided to divide it in two 250 GiB partitions (note that it'll take somewhat less than 1 min. for both partitions to be mounted, after you connect it via USB), which work OK with all usual tools. That's my experience. YMMV, though. But I do believe you're not going to have any troubles with your big USB HDD, as I don't have with mine.
Please kindly redirect me to the appropriate thread, if this topic were discussed before.
The link to using HDDs larger than 137 GB (128 GiB) with Win 9x/ME is at the right side of my signature for a reason: to be easily findable for every member needing it. :whistle:

I strongly recommend that you read it (and all the threads pointed in it) at lenght, after following all the links I provided in this and also in my previous answers to you. :yes:

You'll say: " :blink: but... but... that's *a lot* to read!!!"

The answer is: "of course! But when you have digested all that, you'll know about all that we here collectively found out about this matter, along the years!". ;)

So brace yourself and start reading!

But do remember: your USB HDD will just work with NUSB, no matter whether you have already read or not!

So you can start using it *now*, and do all your reading as time permits, OK?

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There are some messages regarding USB and 137GB limit.
There is no 137GB limit for NUSB. There is no 137GB limit for USB. Period. I'm positive about this.

USB itself has no limit, but some old Hard Drive enclosures might be limited to 137GB if they do not support 48-Bit LBA.

This should not be a problem if you buy an already packaged Hard drive, but could be if you add or replace the drive in an enclosure not rated for the new size.

I have an experimental package to break the 2TB limit but it is currently does not support USB.

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Hi, RLoew! :hello:

Well, since you're reading this, would you be so kind as to tell us a little more about the nature of the VFAT.VxD and about your 1 TiB patch. As I understand, differently from your 2 TiB patch, your 1 TiB patch should work with NUSB, as it just modifies VFAT.VxD... am I right? What happens in a system having an unpatched VFAT.VxD when one writes beyond 1 TiB? Does the system crash, or, worse, VFAT fails silently and renders the FS inconsistent? :ph34r:

Edited by dencorso
Corrected the horrible GiB for TiB typo here too (twice). Thanks a lot for the heads up RLoew!
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dencorso, you use both 1 GiB and 1 TiB as the VFAT.VXD limitation in your posts...

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Filesize limitation doesn't bother me yet.
We're *not* talking about that! We're here talking about FileSystemSize, mind you. The Filesize limit for FAT is 4 GiB - 1 byte or the maximum FileSystemSize, whichever is less. That amouts to 32 MiB for FAT-12, 2 GiB for FAT-16 and, for FAT-32, 4 GiB - 1 byte. That is so because the directory entries in FAT store the Filesize as a 32-bit number.

I was checking whether filesize limit is being referred due to the typo. 1TB limit will be fine for a while.

Thanks for your help.

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I was checking whether filesize limit is being referred due to the typo. 1TB limit will be fine for a while.
Thanks to BenoitRen, :thumbup I finally understood why you remained confused. Yes, that was a most unfortunate one letter typo, because it fostered confusion. Sorry! :blushing: While I'm usually double-careful to revise what I write, there are some typos it takes another pair of eyes to find, because (due to some psycological mechanism I don't even begin to understand) who wrote it will always read what was intended to be written, instead of what actually is set to text.
Thanks for your help.
You're most welcome, oc_dt! :yes:
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Hi, RLoew! :hello:

Well, since you're reading this, would you be so kind as to tell us a little more about the nature of the VFAT.VxD and about your 1 TiB patch. As I understand, differently from your 2 TiB GiB patch, your 1 TiB GiB patch should work with NUSB, as it just modifies VFAT.VxD... am I right? What happens in a system having an unpatched VFAT.VxD when one writes beyond 1 TiB? Does the system crash, or, worse, VFAT fails silently and renders the FS inconsistent? :ph34r:

Watch those typos! 2GiB and 1GiB should be 2TiB and 1TiB respectively.

The 2 versions of the 2TiB Patch both modify ESDI_506.PDR so they will not work with USB.

The 1 TiB limit is due to a flaw in VFAT.VXD that may or may not appear depending upon the alignment of clusters and the page sized blocks (4KiB) used for I/O. The problem generally appears as a system freeze when trying to read directories located above the 1TiB boundary. Fortunately, corruption does not appear to occur. The Patch corrects the code in VFAT.VXD. No other files are modified.

Note: The 1TiB limit applies to the size of a Partition, not the total size of a Drive.

I haven't tested my 1TiB Patch with an USB Drive yet, but it should work. It better, I already started using a 2TB USB Drive for Archiving.

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Watch those typos! 2GiB and 1GiB should be 2TiB and 1TiB respectively.
:blushing: :blushing: They're now corrected, thanks a lot! :thumbup You do rock!

And thanks for the enlightening info!

@all: BTW, perhaps we should open a "Using big USB HDDs thread", as >= 0.5 TiB USB HDDs are becoming affordable. And maybe use these latest posts, from the original oc_dt post as the thread start... If you all find the idea worthwhile I can make it happen. What do you all think?

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Watch those typos! 2GiB and 1GiB should be 2TiB and 1TiB respectively.
:blushing: :blushing: They're now corrected, thanks a lot! :thumbup You do rock!

And thanks for the enlightening info!

@all: BTW, perhaps we should open a "Using big USB HDDs thread", as >= 0.5 TiB USB HDDs are becoming affordable. And maybe use these latest posts, from the original oc_dt post as the thread start... If you all find the idea worthwhile I can make it happen. What do you all think?

It's fine, as it's quite self-contained. Some people including myself will be happy to see that NUSB will function without worry. :hello:

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The 2 versions of the 2TiB Patch both modify ESDI_506.PDR so they will not work with USB.

Could you tell something more about 2 TiB patch?

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Can I ask - why was this thread started in the "Windows 9X member projects" section?

Shouldn't it have been started in the general win9x section?

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Can I ask - why was this thread started in the "Windows 9X member projects" section?

Shouldn't it have been started in the general win9x section?

Ummm, NUSB... and other "patches"...
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