Re: Breaking 137GB Barrier 440BX

Recra <recra05azy@xxxxxxxxx> wrote

440BX chipset (EIDE=UDMA2)
AmiBios 3.1 (circa 1999)

Apologies for as I already know this will be long..

(Skip straight to *** for main question I'm asking.)

I just picked up a 250GB (P)ATA HDD, (Samsung SP2514N), for this
older computer and scratching my head a bit about the 48-bit LBA
137GB barrier.

I'm good with knowing what is needed to get past 137GB: 48-bit LBA
support in the BIOS (or addon hardware) and patched OS's that will
support past 137GB.

First thing I did, of course, was attempt to see if there was a newer
BIOS available, but I had already flashed the last released BIOS
(AmiBios 3.1) for the motherboard years ago. The BIOS has an "enable
LBA/Large Mode" option, but I suspect that is for the old 8GB barrier
and not 48-bit LBA.

I sent the motherboard manufacturer an email asking about 48-bit LBA
support and they responded basically that since this particular
motherboard has onboard SCSI, there was no reason to update the BIOS
for 48-bit LBA EIDE/ATA support. Their assumption then (now?) seems
to be if anyone was going to use a big HDD, it would be SCSI.

Or they are bullshitting and they were too lazy to bother.

Well, I do have a SCSI drive in it, but now I also have
an EIDE drive -- and I want to use this EIDE drive.

So, the BIOS thing isn't going to happen,

There are a few after market bios around,
likely one would support that board.

leaving me other choices, and questions, which I'm starting to
investigate:

- Buying an add-on PCI card that would provide 48-bit LBA support.
This is certaintly the most straight-forward (hardware-wise) option
and would also allow for full use of UDMA5 with the 250GB drive,
however I can see this approach turning into a major pain in the ass.

Cant see that last. A minor pain in the arse at most.

These cards, I assume, would have to have some sort of
onboard BIOS that gets called up during boot. So, with this
card, I'm going to have BIOS's coming up all over the place:

Nope, just one more.

the main motherboard BIOS, the SCSI bios, and then
this one. I can already see them tripping over one another.

They dont in practice.

I really don't want to re-cable either as the way
everything is (literally) packed now, moving one
just one IDE cable around is going to be a bitch.

You can ignore that cable and add a new one with the card.

Where the 250GB HDD is right now, the cable just reaches the
m/b IDE slot. Getting it to reach a PCI location is going to
require moving SCSI bs around, power around, ect.

See above.

Plus, I'm not really wanting to give up an IRQ/PCI
slot unless it is a complete last resort.

It is the most effective way to get 48 bit LBA support if you
dont want to go the after market motherboard bios route.

- BIOS "extensions". I remember many years ago, you could buy a
"BIOS on a (ISA) card" that would either extend the main m/b BIOS
or run in place of it. Anything like this exist today, to do "modern
stuff" like get a 48-bit LBA translator up in memory and cooking?

Havent noticed any, but then I havent looked for them either.

And you'll still lose a card slot.

Also seems, if I'm reading right out there, that there is
a "cottage industry" of customized BIOS'ing going on,
giving support beyond where manufacturers leave off.

Yes, thats the after market motherboard bios I referred to above.

This is all grey to me, so need to read a lot on it.

All you need to know is if your motherboard is supported.

- Dynamic Drive Overlays. Yuck, but maybe.

Not viable with XP.

This is also a last resort. I'm planning on putting a few different OS's
on the HDD, so can already see BS problems creeping up between
the DDO and multi-OS bootloaders. Years ago, I used one of
these translators for some HDD BS limitation (can't remember),

One of the earlier drive size limits.

but it didn't seem to mind sharing the MBR
with the OS bootloader I was using at the time.

Yep, they were reasonably effective.

Brings back memories of the old "Press spacebar to load from floppy".
The overlay ran, then the bootloader, then it would call up whatever
selected -- either win or LILO in the beginning of a Linux part. It
worked then, but I don't trust them today. I bet to give 48-bit LBA
support, its probably too damn big to share with an OS loader.

Its not a size problem. And there is no problem with size anyway.

The more fundamental problem is that you cant use them with XP.

So... Not sure yet, which I want to do, but I
would like to start actually using the drive already...

I can live with it being just a "137GB drive" for now and
use it as such while continuing to investivate the above
approaches, but this leaves me with one (simple?)
question, which I couldn't find a direct answer for:

***

If you don't have 48-bit hardware support, can you use a HDD greater
than 137GB as a "137GB drive" -- and later, if you do apply a 48-bit
LBA hardware support, will the unused space appear as "unallocated"?

Only if you partition it initially so that you have
a 137G partition on the front of the drive.

If you dont do that, it will likely appear to be 250G
and will wrap around at the 137GB level and stomp
over the data at the front of the drive.

(Assuming you are within an OS, patched
and all, that can support 48-bit LBA)

In other words, if you were to use a 250GB HDD as a "137GB HDD"
(because you don't have 48-bit LBA support), are you just using the
first physical 137GB of that drive versus some geometry bull***
going on where you would actually be using the whole drive, but it is
"acting like 137GB"?

Yes, if you do it correctly.

I want to start using the drive now, but want to make sure I'm not
screwed down the road when I decide on a 48-bit LBA approach.

You can get screwed before that with that wrap around problem.

I haven't installed anything, yet, but have poked around the drive
with various utils. Windows sees the entire drive (unallocated)
as 131GB (decimal), while Linux can see the entire (unallocated)
drive as 238GB (decimal).

Yes, its a Win problem, doesnt affect Linux.

Now, I know just because Linux can see the
whole drive, doesn't mean anything. I know
better than to install anything beyond 137GB.

Its quite safe to partition the drive in linux, have
the win partition on the front of the drive, within
the 137G level, use the rest for Linux.

...but the first 137GB should be "fair game" for now?
...and the remaing 113GB usable after deciding on a 48-bit
LBA approach, without impacting anything already installed?

Yes, but you can also keep Win on the front
of the drive and use the rest for Linux too.



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