[LinuxBIOS] 2 Terabyte Limit of BIOS/MBR

[Martin Marcher]

Hello,

hope to be in the right place to ask this, if not just point me to where you
think it's apropriate

my Hardware is:

Tyan Transport GT20 (B2865)
http://www.tyan.com/support_download_manuals.aspx?model=B.GT20B2865

an Areca 1210 raid controller is attached to it and I just was hit by the
2TB limit which a BIOS can handle.

Is that right that the problem is the BIOS?

how I understand the different articles at wikipedia, ms and different
netsources the BIOS just can't handle disks that are larger than 2TB, in
turn this renders a MBR unusable. Fine so I convert the disk to a GPT and
off I should go. But I found that the bios of this board still refuses to
accept the disk (reported as an scsi device from the controller) and just
says "No BIOS disk found".

OK, now the actual question(s):

1) Is this problem (if I understood it right) still there with linuxbios?
2) If so what plans are there to still be able to use a >2TB disk?
(Note: Just plugging a smaller disk to boot from isn't exactly what I
consider a solution, however you are the experts :)

3) Last, not least I couldn't the Tyan GT20 in the supported hardware list,
is that true or just missing.

If it's missing I'll bug Tyan about this once a month or so, in case you
don't have the specs available to send it to you (if you want me to do
that).

thanks
martin

apologies if that is totally OT but I think I'm right here :)

[Carl-Daniel Hailfinger]

On 10.01.2008 21:59, Martin Marcher wrote:
> Hello,
>
> hope to be in the right place to ask this, if not just point me to where you
> think it's apropriate
>
> my Hardware is:
>
> Tyan Transport GT20 (B2865)
> http://www.tyan.com/support_download_manuals.aspx?model=B.GT20B2865
>
> an Areca 1210 raid controller is attached to it and I just was hit by the
> 2TB limit which a BIOS can handle.

Is the RAID array exactly 2 TB? Then the BIOS will see its size as 0.
> Is that right that the problem is the BIOS?

Yes.
> how I understand the different articles at wikipedia, ms and different
> netsources the BIOS just can't handle disks that are larger than 2TB, in
> turn this renders a MBR unusable. Fine so I convert the disk to a GPT and
> off I should go. But I found that the bios of this board still refuses to
> accept the disk (reported as an scsi device from the controller) and just
> says "No BIOS disk found".

Haha. Nice bug.
> OK, now the actual question(s):
> Is this problem (if I understood it right) still there with linuxbios?

Why should we replicate such a bug? If you use Linux as bootloader
inside LinuxBIOS and if the Linux kernel has support for devices >2 TB
enabled (all recent kernels do), you can boot from disks up to 65535 TB
(maybe even 131071 TB) if the adapter creates a virtual SATA device (the
limits are what you would expect from LBA48 addressing). Depending on
the device driver (you said the RAID adapter claims to be SCSI), the
limit may be even higher.
> If so what plans are there to still be able to use a >2TB disk?
>
> (Note: Just plugging a smaller disk to boot from isn't exactly what I
> consider a solution, however you are the experts :)

Three "solutions":
1. Use LinuxBIOS and Linux as Bootloader (LAB)
2. Use the vendor BIOS and boot from a smaller disk
3. Use the vendor BIOS, but make sure the RAID is either smaller than 2
TB or a few GB bigger than 2 TB (in that case the detected size would
probably be real size minus 2 TB). To be honest, this tip may or may not
work, depending on how broken the BIOS is.
> Last, not least I couldn't the Tyan GT20 in the supported hardware list,
>
> is that true or just missing.

True. It should be supportable, though, if we have one board to
experiment with. The Tyan Tomcat K8E S2865 is the board inside according
to the manual.
> If it's missing I'll bug Tyan about this once a month or so, in case you
> don't have the specs available to send it to you (if you want me to do
> that).

How much time are you willing to invest to port LinuxBIOS to the board?

Regards,
Carl-Daniel

2 Terabyte Limit of BIOS/MBR

[Martin Marcher]

On Thursday 10 January 2008 22:55 Carl-Daniel Hailfinger wrote:
> On 10.01.2008 21:59, Martin Marcher wrote:
> > Hello,
> >
> > hope to be in the right place to ask this, if not just point me to where
> > you think it's apropriate
> >
> > my Hardware is:
> >
> > Tyan Transport GT20 (B2865)
> > http://www.tyan.com/support_download_manuals.aspx?model=B.GT20B2865
> >
> > an Areca 1210 raid controller is attached to it and I just was hit by the
> > 2TB limit which a BIOS can handle.
>
> Is the RAID array exactly 2 TB? Then the BIOS will see its size as 0.

nope it's 3TB total. Running debian/etch

we have seperate /boot / partitions and most of the space is used by some
xen domUs. / is inside an LVM (guess that doesn't matter a lot since debian
itself is ready for the large block device support)
> Why should we replicate such a bug? If you use Linux as bootloader
> inside LinuxBIOS and if the Linux kernel has support for devices >2 TB
> enabled (all recent kernels do), you can boot from disks up to 65535 TB
> (maybe even 131071 TB) if the adapter creates a virtual SATA device (the
> limits are what you would expect from LBA48 addressing). Depending on
> the device driver (you said the RAID adapter claims to be SCSI), the
> limit may be even higher.

the problem is I don't get to boot linux. Tried to boot from a cd with only
grub on it but after some reading I concluded that grub relies on the disks
reported from the bios. All grub finds is (cd) and fd0-9 - not a single hd
device.
> Three "solutions":
> Use LinuxBIOS and Linux as Bootloader (LAB)
> Use the vendor BIOS and boot from a smaller disk

I do that right now, but I consider it a not optimal solution
> Use the vendor BIOS, but make sure the RAID is either smaller than 2
>
> TB or a few GB bigger than 2 TB (in that case the detected size would
> probably be real size minus 2 TB). To be honest, this tip may or may not
> work, depending on how broken the BIOS is.

well it's not working since the disk is "stuck" at >2TB (750GB are used the
rest is free, but the raid controller doesn't have an option to shrink it
back)
> > Last, not least I couldn't the Tyan GT20 in the supported hardware
> >
> > list, is that true or just missing.
>
> True. It should be supportable, though, if we have one board to
> experiment with. The Tyan Tomcat K8E S2865 is the board inside according
> to the manual.
> > If it's missing I'll bug Tyan about this once a month or so, in case you
> > don't have the specs available to send it to you (if you want me to do
> > that).
>
> How much time are you willing to invest to port LinuxBIOS to the board?

If it was only me: as much as needed

We are a small company with 2 physical server but given I could find a setup
where I can install and uninstall linuxbios securely (in case it won't
work) I guess I could talk my boss into allowing me to regularly taking the
server down and test the bios - reading up on this in the wiki now

/martin

2 Terabyte Limit of BIOS/MBR

[Peter Stuge]

On Sat, Jan 12, 2008 at 08:20:13PM +0100, Martin Marcher wrote:
> We are a small company with 2 physical server but given I could
> find a setup where I can install and uninstall linuxbios securely
> (in case it won't work)

I suggest a BIOS savior. Pretty cheap and a great way to switch
between flash chips.

Make sure you get the RD1-LPC8 which is 8Mbit, ie. 1Mbyte. That may
be enough for a LAB (Linux as bootloader) coreboot with your needed
drivers, but then it should probably kexec your normal system kernel.

//Peter

[Torsten Duwe]

On Thursday 10 January 2008, Martin Marcher wrote:
> the BIOS just can't handle disks that are larger than 2TB, in

In theory a legacy BIOS should be able to at least access the first 2TB. The 
limit stems from 512 bytes block size and counting blocks in 32-bit integers, 
which is done in a classic DOS disk label, in the MBR.
> Fine so I convert the disk to a GPT and
> off I should go.

Does your legacy BIOS support GPT? unlikely.
> OK, now the actual question(s):
> Is this problem (if I understood it right) still there with linuxbios?

LinuxBIOS itself isn't directly considered with disks besides initialising the 
controller. Look at the section "Payloads" in the wiki. Most of them are open 
source, BTW 8-)
> If so what plans are there to still be able to use a >2TB disk?

Make a DOS (legacy BIOS) _partition_ of small size to boot from, at the start 
of the disk. Make sure it's consistent with the GPT label. If that does not 
help, you _need_ LinuxBIOS and a capable payload, or a guru boot setup.
> Last, not least I couldn't the Tyan GT20 in the supported hardware list,
>
> is that true or just missing.

Tyan is LinuxBIOS-friendly, behind the scenes, if the 2865(?) board is not 
supported maybe there's a way (the S2912 is supported).
> If it's missing I'll bug Tyan about this once a month or so, in case you
> don't have the specs available to send it to you (if you want me to do
> that).

Anyone here ready to do the port?
> apologies if that is totally OT but I think I'm right here :)

Not with questions about legacy BIOSes, but with datasheets you are ;-)

Torsten

On Thu, Jan 10, 2008 at 09:59:14PM +0100, Martin Marcher wrote:
> Hello,
>
> hope to be in the right place to ask this, if not just point me to where you
> think it's apropriate
>
> my Hardware is:
>
> Tyan Transport GT20 (B2865)
> http://www.tyan.com/support_download_manuals.aspx?model=B.GT20B2865
>
> an Areca 1210 raid controller is attached to it and I just was hit by the
> 2TB limit which a BIOS can handle.
>
> Is that right that the problem is the BIOS?

Or at least a problem with the Areca BIOS extension.
Could also be the main Tyan BIOS too I suppose.

INT13h Extensions support 64-bit LBAs, so that's not an inherent
problem unless there are limitations of the BIOSes's implementations.
> how I understand the different articles at wikipedia, ms and different
> netsources the BIOS just can't handle disks that are larger than 2TB, in
> turn this renders a MBR unusable. Fine so I convert the disk to a GPT and
> off I should go. But I found that the bios of this board still refuses to
> accept the disk (reported as an scsi device from the controller) and just
> says "No BIOS disk found".

Well, you're distorting some things there.  The BIOS itself
just provides functions for disk access, and by itself, is
incapable of understanding partition tables.

Also, the limitations of 32-bit Windows® are totally irrelevant. :)

Now to get remotely on-topic:
If you're not interested in the task of porting LB to your board,
I'd start bugging both Tyan and Areca.

Jonathan Kollasch

[Stefan Reinauer]

* [e-mail]  [080111 03:47]:
> > how I understand the different articles at wikipedia, ms and different
> > netsources the BIOS just can't handle disks that are larger than 2TB, in
> > turn this renders a MBR unusable. Fine so I convert the disk to a GPT and
> > off I should go. But I found that the bios of this board still refuses to
> > accept the disk (reported as an scsi device from the controller) and just
> > says "No BIOS disk found".
>
> Well, you're distorting some things there.  The BIOS itself
> just provides functions for disk access, and by itself, is
> incapable of understanding partition tables.

While I thought this initially, I now believe this is not exactly true.
Many systems are nowadays installed in a way that the MBR does not
contain the bootblock code, but instead points to an active primary
partition that contains the partition bootblock. This implies that the
BIOS knows how to parse the MBR and run the partition bootblock.

Stefan

2 Terabyte Limit of BIOS/MBR

[Martin Marcher]

On Friday 11 January 2008 03:47 [e-mail] wrote:
> > Is that right that the problem is the BIOS?
>
> Or at least a problem with the Areca BIOS extension.
> Could also be the main Tyan BIOS too I suppose.

I guess it's not a problem of the Areca controller since it's bios sees the
created drive just fine with the correct size.
> INT13h Extensions support 64-bit LBAs, so that's not an inherent
> problem unless there are limitations of the BIOSes's implementations.
> > how I understand the different articles at wikipedia, ms and different
> > netsources the BIOS just can't handle disks that are larger than 2TB, in
> > turn this renders a MBR unusable. Fine so I convert the disk to a GPT and
> > off I should go. But I found that the bios of this board still refuses to
> > accept the disk (reported as an scsi device from the controller) and just
> > says "No BIOS disk found".
>
> Well, you're distorting some things there.  The BIOS itself
> just provides functions for disk access, and by itself, is
> incapable of understanding partition tables.

That was badly stated, see my other posts. Booting from a grub disk still
won't work (grub doesn't see any disk)

as soon as i boot from an external usb drive all is fine and from the point
where linux boots I have full access to the drive. Seeing all available,
partitioned and unpartitioned disk space.
> Also, the limitations of 32-bit Windows® are totally irrelevant. :)

no windows here, debian/etch x86_64, being totally new to this i just found
that a few pages at MS explained basics actually quite good.

/martin