GPT partitioning, why or why not?

[williwaw]

A number of new installers and boot loader are being developed and used in puppy.
For a newer (UFEI) machine, are there reasons why to use gpt partitioning..... or good reasons why not?

[JASpup]

timely

I have two machines booted and data I want from a USB-HD. The machine that needs the data has an old os booted that doesn't support GPT, so the second machine, the one I'm typing on, was booted to retrieve the data from a newer external HD.

We (collectively) use old computers and GPT is not fully compatible. That's a reason.

I imagine when we stop writing about 32-bit there won't be an issue.

Otherwise I don't miss the fact that my 32 & 64 machines don't share bootloaders, but I have thought about it.

[JASpup]

Redmondtopia doesn't care about this at all, and HD manufacturers will assert a current os as a system requirement, GPT the typical reason.

It's alienating to people who aren't super technical or who don't want the hassle of reformatting a HD before use.

[Adam Li]

Hi to all

Shorty:
1. If HDD is up to 2 TB you can use GPT or MBR, if >2TB MBR cannot be used.
2. UEFI or BIOS is another story - older BIOS don't "understand" GPT.
3. GPT can be set to Legacy BIOS bootable - I never used this and I don't know is this working.

On Wikipedia:
GUID Partition Table
EFI system partition
Unified Extensible Firmware Interface

AOMEI:
MBR vs GPT: Which One Is Better for You?

EaseUS:
MBR VS GPT | What's the Difference and Which Is Better

MiniTool:
MBR vs. GPT Guide: What's The Difference and Which One Is Better [MiniTool Tips]

Have a nice day
Adam

[rcrsn51]

For years, I have been formatting the hard drives on old BIOS machines as GPT and booting them with Legacy GRUB or GRUB2.

That way, they are not limited to four primary partitions.

[dimkr]

AFAIK you must use GPT if you intend to boot in UEFI (rather than, BIOS) mode.

[rcrsn51]

AFAIK you must use GPT if you intend to boot in UEFI (rather than, BIOS) mode.

Evidence, please.

In the Starter Kit thread, I describe how to build a multi-purpose flash drive with Grub4Dos on the MBR and a UEFI-bootable EFI partition.

As a general rule, UEFI firmware is aware of MBR-structured drives. However, there are many variations on how the UEFI specs are implemented on different machines.

[Jafadmin]

AFAIK you must use GPT if you intend to boot in UEFI (rather than, BIOS) mode.

This isn't correct.

[williwaw]

Still reading up on this, but it seems? redmond made some decisions about their preferred setup...

Usually, MBR and BIOS (MBR + BIOS), and GPT and UEFI (GPT + UEFI) go hand in hand. This is compulsory for some operating systems (eg. Windows), while optional for others (eg. Linux).

Question 2: when reformatting a disk with a GPT partition table, to use with a msdos table, is it necessary or recommended to remove the 2nd GPT table at the end of the drive?

[rcrsn51]

Question 2: when reformatting a disk with a GPT partition table, to use with a msdos table, is it necessary or recommended to remove the 2nd GPT table at the end of the drive?

If you tell Gparted to switch a GPT drive to MSDOS structure, it's going to allocate the available space to whatever partitions you want to create. The previous secondary GPT table would automatically go into the pool of available space. There would be no need for the user to do anything extra.

[Jafadmin]

It isn't an either/or world.

If you need more than 5 partitions on a disk, or need partitions larger than 2T, use GPT. Otherwise, use MBR.

[tosim]

Don't forget about the use of an Extended Partition.

[rcrsn51]

Don't forget about the use of an Extended Partition.

One of the objectives of GPT was to finally eliminate the dreadful hack of Extended Partitions.

[tosim]

True, I had forgotten that. Thank you.

[mikeslr]

Don't forget about the use of an Extended Partition.

One of the objectives of GPT was to finally eliminate the dreadful hack of Extended Partitions.

I think it was mikeb who advised on the 'old forum' that Extended Partitions were experimental. I imagine the back story to be that it was never perfected but retained because its rewards exceeded its risks; there apparently being no other way to avoid the 4 primary partition msdos restriction. And with no alternative, why keep mentioning its experimental status.
Mikeb's (?) post was in reply to my query for advice. At the time I had created several extended partitions on which my Puppys and other Linux Distros were located. I still often had to boot into Windows. On several occasions when a Linux OS was selected from grub4dos' menu.lst it would fail to boot because the entire Extended Partition was no longer 'present'. To recover, I had to boot into Windows and run a Partition Recovery program.
Subsequently, I only used Primary Partitions, limiting* myself to One Major Distro and the inconvenience of an apparently messy partition with that Distro and an assortment of Puppys and their SFSes. The problem has not reoccurred.

-=-=-=-
With Windows 7 and up, computers often come with three of the four possible primary msdos partition already in use: a small boot partition; a 10Gb +/- recovery partition and the rest of the hard-drive being an ntfs partition occupied by Windows and its programs. There is software to copy/move the recovery files onto a USB-Key eliminating them (and their partition) from the hard-drive. That drive can then be re-structured to hold two Linux formatted partitions. And, of course, additional drives can be added to one's system one way or another.

[mistfire]

I will go for GPT

Reasons:
1. More resilient than MBR because GPT was stores file tables on both start sector and end sector of partition. Thus easily to recover corrupted files
2. Plenty of partitions to create without worries
3. Large drive support

Drawbacks:
Requires UEFI support

[rcrsn51]

Drawbacks:
Requires UEFI support

Wrong. Did you bother to read the whole thread?

[sonny]

GPT, not MBR ... if you wish to see your Puppy and Windows 10 sleep on the same bed

[bigpup]

Only issue I know about, is Grub4dos Config, trying to install a boot loader.
GPT does not have an MBR area.
The Grub4dos boot loader has to use the MBR for some of it;s files.
No MBR, no place to put needed files.
Can not use Grub4dos boot loader on GPT.

Really old Bios firmware may only look for boot stuff on an MBR section of the drive.

[rcrsn51]

GPT, not MBR ... if you wish to see your Puppy and Windows 10 sleep on the same bed

Not necessarily. Many commercially refurbished machines have a Win10 install on an MBR hard drive.

[rcrsn51]

Only issue I know about, is Grub4dos Config, trying to install a boot loader.
GPT does not have an MBR area.
The Grub4dos boot loader has to use the MBR for some of it;s files.
No MBR, no place to put needed files.
Can not use Grub4dos boot loader on GPT.

The MBR is the single 512 byte sector at the start of the drive. It exists regardless of the drive structure and is recognized as part of GPT.

In addition to the MBR, Grub4Dos uses some of the free space between the MBR and the start of the first partition.

But that space is also used by a GPT partition table - hence the conflict,

This was all discussed in detail in the old forum.

[bigpup]

OK.
GPT does not have the same MBR setup as msdos partition table.

at the beginning of GPT partition table, there is still stored a legacy MBR which can help to prevent MBR-based disk utilities from misrecognizing and overwriting GPT disk. This sector is referred to as a “protective MBR”. In the operating system which supports GPT-based boot, the first sector is also used to store the first stage of the boot code. There is a partition typed wit 0xEE in the protective MBR, which indicates the disk employs GUID partition table. Operating systems which cannot read GPT disks will regard the partition as unknown and will refuse to modify the disk unless users delete this partition, which minimizes accidental deletion. In addition, the operating system which can read GPT disk will check partition table in the protective MBR, and if the partition type is not OxEE or if there are multiple items on the partition table, the OS will refuse to manipulate the hard disk, too.

Recently reading about changes to UEFI firmware.
The newer or newest ones, just auto switch to legacy bios mode, if they detect a drive using msdos partition table MBR.

[LateAdopter]

Grub4DOS 0.4.6a has had GPT support for about 5 years, but Grub4DOSconfig is older than that.

Tinybit's version of bootlace.com with the --gpt option puts the bootcode in the reserved 63 sectors but above the GPT. yaya's version puts it outside of the reserved area in no-mans-land .

bootlace.com can also put it in the proper place in the partition boot area.

[rcrsn51]

In the operating system which supports GPT-based boot, the first sector is also used to store the first stage of the boot code.

This means that on a BIOS system with GPT, you can safely put GRUB Stage1 on the MBR and boot a Linux. This can be either Legacy GRUB or GRUB2.

It also means that a UEFI machine in Legacy Mode can boot off a GPT drive, depending on what the UEFI firmware allows.

[BarryK]

AFAIK you must use GPT if you intend to boot in UEFI (rather than, BIOS) mode.

As already replied, this is incorrect. I can also add my experience on many UEFI computers, MBR works fine.

The EasyOS USB flash stick is only MBR, with both refind for UEFI booting and syslinux for traditional-BIOS booting, and have never had a report that it won't boot.