47 replies to this topic

[Sha0]

I think you might fail to understand disk layout. The disks you are used to have an MBR, likely followed by some padding, then partitions. XP reads the MBR to know what partitions exist. GPT disks have a different layout. GPT does include a "legacy MBR", but it is not guaranteed to reflect any partitions, since GPT allows for more than four partitions and there's not a lot of meaning for that fact that can be packed into an MBR. So XP doesn't support GPT disks. It doesn't even get as far as seeing partitions, because it sees no MBR.

[roamer_1]

I think you might fail to understand disk layout. The disks you are used to have an MBR, likely followed by some padding, then partitions. XP reads the MBR to know what partitions exist. GPT disks have a different layout. GPT does include a "legacy MBR", but it is not guaranteed to reflect any partitions, since GPT allows for more than four partitions and there's not a lot of meaning for that fact that can be packed into an MBR. So XP doesn't support GPT disks. It doesn't even get as far as seeing partitions, because it sees no MBR.

Yes, I DO understand that. I cannot see system or multi-partitioned drives. I get it. But a *single* partition without system - Why can't I see that? Unless you are telling me that every drive spawned by a Vista+ machine (in normal operations, no fancy stuff) always has GPT disks by default... In which case I am boned. But then, how can others on this thread see them? Or is that simply because an action was taken to CHOOSE to create a basic disk, which would not normally be created?

[Sha0]

Could be a popular choice at factories to use GPT now.

Yes, even a single partition on a GPT disk could have no MBR entry... Because its partition info is in the GPT instead, which XP does not support as per the FAQ link I gave earlier.

[roamer_1]

Could be a popular choice at factories to use GPT now.

Yes, even a single partition on a GPT disk could have no MBR entry... Because its partition info is in the GPT instead, which XP does not support as per the FAQ link I gave earlier.

Then I am chasing my tail. all I can do is kill the MBR/part info in order to see the drive at all, and go to recovery methods.
That is not worth it. Not on every bloody one of them.

[Sha0]

It would be good to know if that's even your problem, though. It is possible to actually convert GPT disks to MBR disks, and thus access up to four partitions. If you get a chance to find out about sector 1, it would be interesting if GPT is not the issue at all.

[roamer_1]

It would be good to know if that's even your problem, though. It is possible to actually convert GPT disks to MBR disks, and thus access up to four partitions. If you get a chance to find out about sector 1, it would be interesting if GPT is not the issue at all.

Oh, I will push on with my experiment, never fear. Too far along to quit now.

I will know by tomorrow. I will be sure to come back and let you (all) know.

But I had better get at it if I am going to get it done tonight.

Good night to you, and thanks again

[karyonix]

From earlier roamer_1's posts I thought disks don't appear in Deice Manager.
Later, he revealed that he can format the disk in Windows XP. At last, he admitted that he saw one partition.
I agree with Sha0 that it is probably GPT disk and the partition is GPT protective partition.

I try installation of Windows 7 Home Premium on new uninitialized 9000MB disk (in VirtualBox).
It automatically initializes the disk as MBR disk and creates 2 primary partition. One partition is without drive letter. Another partition is C:.

Most people don't have this problem because they usually use MBR partition scheme (It is default for at least for small disk).
But roamer_1's customer uses GPT.

This is not related to NTFS at all.

[Wonko the Sane]

This is not related to NTFS at all.

Q.E.D.:
http://en.wikipedia.org/wiki/Q.E.D.


http://www.microsoft...ge/GPT_FAQ.mspx

Windows XP Disk Support

13. Can Windows XP x64 read, write, and boot from GPT disks?
Windows XP x64 edition can use GPT disks for data only. Only Windows for Itanium-based systems can boot from GPT partitions.

14. Can the 32-bit version of Windows XP read, write, and boot from GPT disks?
No. The 32-bit version will see only the Protective MBR. The EE partition will not be mounted or otherwise exposed to application software.

15. Can the 32-bit versions of Windows Server 2003 read, write, and boot from GPT disks?
All versions of Windows 2003 since Server Pack 1 can use GPT partitioned disks for data. Booting is only supported for Itanium-based systems.

16. Can Windows Vista and Windows Server 2008 read, write, and boot from GPT disks?
Yes, all versions can use GPT partitioned disks for data. Booting is only supported for EFI-based systems.

17. Can Windows 2000, Windows NT 4, or Windows 95/98 read, write, and boot from GPT?
No. Again, legacy software will see only the Protective MBR.

COMMERCIAL (but at 20 bucks affordable):
http://www.mediafour...cts/gptmounter/

FREEWARE :
http://www.rodsbooks.com/gdisk/
(you can make a hybrid MBR in most cases):
http://www.rodsbooks...isk/hybrid.html


Wonko

[MedEvil]

Can someone tell me, which file it is, which handles MBR, GPT access? Is it the disk driver?

[karyonix]

@MedEvil
I think it's partmgr.sys (disk class upper filter driver).

[MedEvil]

@MedEvil
I think it's partmgr.sys (disk class upper filter driver).

Thank you.
So transplanting a Win2k3 partmgr.sys into a XP based LiveCD, should give it the ability to read GPT Drives?

But i guess there is one more file, which deals with it MBR/GPT, since M$ clearly distinguishes between reading from a GPT drive and booting from a GPT drive.
Does the boot loader need to be able to handle GPT, even when it uses BIOS calls?

[karyonix]

Does the boot loader need to be able to handle GPT, even when it uses BIOS calls?

Sure.
Normal PC BIOS don't know anything about partitioning. It just provide access to disk at the physical drive level (or equivalent such as RAID volume).
While booting BIOS just check that the first sector has 55 AA ending. It then transfer control to the first sector.
"Whether the disk is partitioned or not" and "how it is partitioned" is "program in the disk"'s business.

[Wonko the Sane]

Does the boot loader need to be able to handle GPT, even when it uses BIOS calls?

Sure.

Read the given link about "hybrid" MBR's, the topic is cleared enough.


Wonko

[MedEvil]

How does one create a GPT drive, for test purposes?

[Wonko the Sane]

How does one create a GPT drive, for test purposes?

Is your google broken? Or your spectacles and you cannot read anymore? Nahh, then whatever we write here would be completely unuseful.

Like converting an existing MBR one?
http://www.rodsbooks...sk/mbr2gpt.html
(SAME site ALREADY linked TWICE)

Or creating one from scratch on a OS that supports it's creation?
http://www.microsoft...e.mspx?mfr=true
http://www.microsoft...gpt-on-x64.mspx
http://support.micro...kb/300415/en-us
(first hits, besides the already given link, with google for "microsoft.com gpt create")

Taking spoon feeding to a next level?


Wonko

[MedEvil]

Taking spoon feeding to a next level?

You're right. Why should i spend time to patch a solutions together? People, who want this, can do this themselfs.

[Wonko the Sane]

You're right. Why should i spend time to patch a solutions together? People, who want this, can do this themselfs.

Actually I was referring to the utter slothfulness transpiring from your question:

How does one create a GPT drive, for test purposes?

I am well sure you could have found the answer to that question in under five minutes, had you really tried looking for it, and the "spoon feeding" was the description of my providing an answer to your question.

How you should spend your time and why it's entirely part of your freedom, obviously.


Wonko

[Sha0]

Though sometimes one might ask a question on behalf of the voice inside the head of the reader, just so that the reader is forced to ask that question in their head. Not saying that's the case here. For example, "how might someone feel after reading my post?" I forget to ask that question sometimes.

[Wonko the Sane]

Though sometimes one might ask a question on behalf of the voice inside the head of the reader, just so that the reader is forced to ask that question in their head. Not saying that's the case here. For example, "how might someone feel after reading my post?" I forget to ask that question sometimes.

Sure , but as well one could reply "on behalf" of the voices he thinks he hears in his or in someone else's head. Obviously not saying that's the case here. For example, "No one cares."

Wouldn't this resolve to a pretty much pointless exchange of ideas?

Maybe it is better if everyone will mantain the paternity of what he/she writes, and doesn't post "on behalf" of anyone else, and definitely not "on behalf" of voices in anyone's head...


Wonko

[Sha0]

Sure , but as well one could reply "on behalf" of the voices he thinks he hears in his or in someone else's head. Obviously not saying that's the case here. For example, "No one cares."

Well, different people have different ideas about customer service. Of course, customers usually pay.

Wouldn't this resolve to a pretty much pointless exchange of ideas?

I disagree. "Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime." Forgive the gender bias, but it's a quote. Encouraging questioning and exploration for findings answers is obviously important from

Is your google broken? Or your spectacles and you cannot read anymore? ...

There are a variety of ways to go about this encouragement, however. Asking a question you don't need/already have the answer for just so the reader asks it is just one way. Sometimes it's followed by this "smiley":

Maybe it is better if everyone will mantain the paternity of what he/she writes, and doesn't post "on behalf" of anyone else, and definitely not "on behalf" of voices in anyone's head...

There's also a useful skill in helping to facilitate someone in error to "save face." It can help to secure productive working relationships. Sorry about preaching. I value these relationships.

[Wonko the Sane]

I disagree. "Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime." Forgive the gender bias, but it's a quote. Encouraging questioning and exploration for findings answers is obviously important from

Sure.
That's a quote, and exactly one that I try my best to have reality "conform" to.

Unfortunately the actual result is not always the one expected :

Give a man a fish; you have fed him for today. Teach a man to fish, and he will sit in the boat and drink beer all day.

Wonko

[roamer_1]

It would be good to know if that's even your problem, though. It is possible to actually convert GPT disks to MBR disks, and thus access up to four partitions. If you get a chance to find out about sector 1, it would be interesting if GPT is not the issue at all.

All right, I have some results to report.

The new OS, made from a fresh OEM XP SP-3 CD (not slipstreamed) reads the known good 160g drive created on Vista.
The installation is now carrying 90% of my base software, and results remain the same.

Yesterday I created a fresh, bare CD from my old slipstreamed cabs, and installed it to another HDD. The installation is bone stock (no software)
That OS cannot read the 160g drive created by Vista.

So, it seems my old master set was the problem, and has been the problem all along - though I don't know why. I don't really care why at this point, as the problem is resolved. I just need to update my Live disk master to sp-3 and the whole thing is behind me.

However, the "GPT" thing remains, and I haven't yet determined if I can read an actual boot drive... With that in mind, I think I would be better off to begin the process of upgrading the bench to win7, to guarantee compatibility. *sigh* triple booting again.

Thanks again for your help (and everyone else too).

-Bruce

[Wonko the Sane]

....
The new OS, made from a fresh OEM XP SP-3 CD (not slipstreamed) reads the known good 160g drive created on Vista.
....
Thanks again for your help (and everyone else too).

Good.

Now that the problem has been solved, maybe, for next time, it is the case to point you to the "common sense advice" attached to Rules, expecially point #f.
http://www.boot-land...?showtopic=9101



Wonko