[GTALUG] MBR and GTP Drives

Howard Gibson hgibson at eol.ca
Mon Oct 9 12:43:41 EDT 2017


On Sun, 8 Oct 2017 12:47:41 -0400 (EDT)
"D. Hugh Redelmeier via talk" <talk at gtalug.org> wrote:

> | From: Howard Gibson via talk <talk at gtalug.org>
> 
> It is "GUID Partition Table" -- GPT, not GTP.  Nit picky, I know, but it 
> might affect your success googling.

   Oops.  My bad.  It is GPT in my notes.
> 
> | Motherboard:  Gigabyte GA-990FXA-UD3 Version~1.1. (Version 3.0 supports GTP)
> 
> The right way of thinking aout it is: does the motherboard have UEFI
> firmware.  GPT is a consequence.
> ...
> So: I conclude that your MB, being Version 1.1, does NOT have UEFI.
> Perhaps Versions and Revisions are different things and I've got it
> wrong.

  My MoBo has "Version 1.1" printed on one corner of the board.  I am a mechanical designer (with training in UNIX administration).  I prepare engineering drawings. I would call this a Revision.  The MIL and ASME standard recommend revision letters, not numbers.  Manufacturers use whatever terminology they please.  Definitely, this is hardware. 

> I would have thought that a firmware update could have fixed this, but
> apparently not.
> 
> | New drive:    Western Digital 2000GB SATA WD2003FZEX-0.
> | Newer drive:  Seagate ``Desktop HDD'' 2TB SATA. ST2000DM001-1ER1
> 
> (You had problems with the WD drive but not the Seagate.)
> 
> If I remember correctly, MBR tops out at 2T.  So GPT is a good choice,
> but not required.
> 
> Then there is the issue of sector size.  As drives got to this size,
> they started making sectors larger than 512 bytes.  Or rather they
> made these sector sizes visible to some extent.  There were a lot of
> games with how much they were willing to fake 512 byte sectors for the
> sake of old BIOSes and old OSes.
> 
> The ST2000DM001-1ER1 has 4K sectors but that it will emulate 512-byte
> sectors.
> <http://www.seagate.com/staticfiles/support/docs/manual/desktop/Barracuda%207200.14/100686584.pdf>
> 
> It is not as clear what the WD drive does about sector size.
> <http://products.wdc.com/library/SpecSheet/ENG/2879-771434.pdf>
> <https://superuser.com/questions/1021574/difference-between-wd2003fzex-and-wd2003fyps-wd-desktop-hdds>
> That says "Advanced Format (AF): Yes".
> "Advanced Format" is Western Digital's term for 4K sectors.
> 
> I don't know how to get the WD to emulate 512-byte sectors so that a
> BIOS could boot from it.  I would expect it to be able to work
> somehow.
> 
> If you are booting from an MBR-based system, I'm pretty sure you need
> that 512-byte emulation.
> 
> The transition to 4k sectors was a mess.  The disk manufacturers tried
> to paper it over and just created more complexity.  And they explained
> little, leaving us to learn from experimentation just what was going
> on.  I've forgotten much of what I did learn.
> 
> |    I am now completing my most difficult Linux install ever.  My old 
> | hard drive with / and /home and /usr/local on it has died.  My new 2TB 
> | drive was formatted for GTP.  The Fedora installer warned me that GTP 
> | drives requre a /boot/efi partition.
> 
> I don't think that that is the case.
> 
> If you are booting using UEFI, you surely need a /boot/efi (an EFI
> System Partition).  But your motherboard is incapable of booting with
> UEFI.

   I added a 4TB drive to my Fedora system a few years ago.  This was and is a backup device.  I do not install the OS onto it.  The hardware replacement simply worked.  I formatted it and mounted it.  When I upgraded to a new Fedora, the install program insisted I needed a /boot/efi partition for the new GPT system.  This is in spite of my old MBR system drive.  I unplugged the 4TB GPT drive.  I installed then I plugged it in again.  Everything works fine.  This may be a glitch in the Fedora install.

> |  Regardless of how I partitioned, 
> | the system would not boot.  I converted the drive to MBR format.  The 
> | best I could get was to see the available kernels.  It would not boot.  
> 
> Do you know whether the sectors looked to be 512 bytes to the BIOS?
> To the Fedora installer?

  No I don't...

[root at Rev ~]# fdisk /dev/sda  <<<<< My new Seagate system drive
Command (m for help): p
Disk /dev/sda: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0xdf4e0a6e

Device     Boot      Start        End    Sectors   Size Id Type
/dev/sda1             2048 2343751679 2343749632   1.1T 83 Linux
/dev/sda2       2343751680 3398438911 1054687232 502.9G 83 Linux
/dev/sda3  *    3398438912 3789062143  390623232 186.3G 83 Linux
/dev/sda4       3789062144 3907028991  117966848  56.3G  5 Extended
/dev/sda5       3789066240 3906252799  117186560  55.9G 82 Linux swap / Solaris
Command (m for help): q
[root at Rev ~]# fdisk /dev/sdb  <<<< My newish GPT backup drive
Command (m for help): p
Disk /dev/sdb: 3.7 TiB, 4000787030016 bytes, 7814037168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: A6FA1960-3E6A-4C79-81F7-0C7354E0DC5E
Device     Start        End    Sectors  Size Type
/dev/sdb1   2048 7814037134 7814035087  3.7T Linux filesystem
Command (m for help): q
[root at Rev ~]# fdisk /dev/sdc   <<<<< My new ex-system now archive drive
Command (m for help): p
Disk /dev/sdc: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x9cf133fe
Device     Boot Start        End    Sectors  Size Id Type
/dev/sdc1        2048 3906250751 3906248704  1.8T 83 Linux
Command (m for help): q

  The Disklabel type was GPT, but I reformatted it using dgisk. 

> | I got fed up and I bought another new drive, and everything installed 
> | and booted effortlessly.
> | 
> | Motherboard:  Gigabyte GA-990FXA-UD3 Version~1.1. (Version 3.0 supports GTP)
> | New drive:    Western Digital 2000GB SATA WD2003FZEX-0.
> | Newer drive:  Seagate ``Desktop HDD'' 2TB SATA. ST2000DM001-1ER1
> | 
> |    From fdisk, I could see that the Western Digital drive was GTP.  The 
> | new Seagate drive identified itself as "dos", which means it is MBR.  
> | Best Buy offered me a newer Seagate at a slightly lower price but one is 
> | claimed explicity to support Linux, and it supports some older 
> | protocols.  When I told the people at the store I wanted MBR, not GTP, 
> | they just stared at me.
> 
> Don't accept the partitioning done by the factory.  It's just one more
> unknown in the mix.
> 
> Personally, I'd choose GPT these days.
> 
> |    The Western Digital drive works.  It just does not work as a boot 
> | drive.  I now have an /archive file system.
> 
> Sounds like a sector size problem.
> 
> |    I put my install instructions up on my website in the hopes that I am 
> | helping newbies.  I am trying to make sense of all this.  Right now, I 
> | figure if you have an old computer with an old hard drive that works, 
> | you should be able to install Linux.  If you have a new (GTP) system 
> | that works, you should be able to intall Linux on it.  If you have an 
> | old clunker and the hard drive dies, look out!
> | 
> |    Is this a Seagate versus Western Digital issue, or is my WD drive 
> | flakey?  Can anybody make sense of all this?  I would like to write this 
> | up as a useful document.
> 
> Writing this up accurately requires a lot of testing of a diverse
> collection of systems.
> 
> Since your current setup works, I imagine you have no desire to go
> back and start again.

   Nooooo.  

> Luckily this set of problems will go away as the old hardware retires.
> But new problems will replace them!

  My motherboard is five years old.  One of the things Linux is supposed to do is work on old computers.  Mine still is reasonably new.  It sounds like people running old computers need to by hard drives from second hand stores. 

-- 
Howard Gibson 
hgibson at eol.ca
jhowardgibson at gmail.com
http://home.eol.ca/~hgibson


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