Re: [gentoo-user] Trouble with backup harddisks

[tuxic@posteo.de]

On 05/02 09:49, Andrea Conti wrote:
> > I think, I feel better if I repartitioning/reformat both drives,
> > though.
> 
> It's not necessary, but if it makes you feel better by all means do so.
> 
> > *GPT/MBR
> > From a discussion based on a "GPT or MBR for my system drive" in
> > conjunction with UEFI it was said, that GPT is more modern and
> > save.
> 
> 
> More modern I concur. For the rest it's mainly about features: >2TB partitions and way more metadata, plus not having to bother with CHS values which make no sense in today's drives.
> And being able to define >4 partitions without littering the disk with extended boot records, which is probably the only thing I'd call "safer".
> 
> My point was that none of this is relevant in an external drive which is under 1TB and will only hold a single partition starting at sector 1 and spanning the rest of the disk.
> A system drive, especially if booting from UEFI is a different case for which GPT absolutely makes sense.
> 

Ok, the other way around: Does GPT hurt more than MBT on a external HD
used for backup puporses (no boot), has 1T and 1 partion of that size?


> > My question was meant not so much as "MBR or GPT?" 
> > but more whether there are some variants of GPT (with 
> > protected MBR for example -- which was completly new to me),
> > which I should use or avoid.
> 
> There are really no "variants" of GPT. The protective MBR is only there to make all space in the disk look allocated to MBR partitioning tools that are not GPT-aware, and is automatically written for you by all GPT partitioning tools.
> 
> In addition to the opaque entry of type 0xee, this MBR can also contain entries pointing to at least some of the actual partitions; this is called a 'hybrid' MBR and allows MBR-only access to partitions that are within the limits of MBR addressing (start and end sector <2TB). These are only useful in very specific cases an I would consider them a hack more than a solution; while gpt-fdisk has some support for creating hybrid MBRs (don't know about fdisk), you won't get one unless you specifically ask for it.
>: 

Thanks of the information! :)

> > But: Are rescue systems for USB-stick more UEFI/GPT aware nowadays
> > or "traditionally" based on MBR/BIOS-boot?
> 
> I think that anything that's not ancient will have tools and kernel support for both MBR and GPT, and will boot fine in both BIOS and UEFI modes.
> 
> > One thing I found is really handy: An USB-stick with an rEfind
> > installation. As long as your PC supports UEFI (or can switched to it)
> > rEfind is able to boot "everything" without prior configuration.
> 
> You can probably do the same with GRUB2, albeit in a way less user-friendly fashion :)
> But why do you consider the ability to boot anything but the rescue system itself important in a rescue system?

Recently a BIOS update deleted all UEFI entries and the system no
longer boots. With rEfind from a USBstick I was able to boot
the sustem nonetheless and the reinstallation of grub solves
the problem.
Task accomplished! :)

> > 
> > Some rescue-system which really shines and with which you have made good
> > experiences?
> 
> My usual go-to is SystemRescueCD (the old 5.x gentoo-based one). 
> 
> andrea

Thanks for the info, Andrea!

Cheers!
Meino