[gentoo-user] Re: Re: Partition of 3TB USB drive not detected

[Jörg Schaible]

james wrote:

> On 07/31/2016 12:56 PM, Jörg Schaible wrote:
>> Jörg Schaible wrote:
>>
>>> Hi Daniel,
>>>
>>> thanks for your response.
>>>
>>> Daniel Frey wrote:
>>>
>>> [snip]
>>>
>>>> I can only think of two reasons, the kernel on the livecd doesn't
>>>> support GPT (which is unlikely)
>>>
>>> That would be really strange. However, how can I prove it?
>>>
>>>> or you're booting a 32-bit kernel live
>>>> USB. I am reasonably certain for drives > 2TB a 64-bit kernel and GPT
>>>> are required.
>>>
>>> No, I've always chosen 64-bit kernels. I wonder what is so special about
>>> this partition ...
>>
>> Currently I wonder, why my system can find the partition at all:
>>
>> ======================== %< ========================
>> # gdisk -l /dev/sdi
>> GPT fdisk (gdisk) version 1.0.1
>>
>> Partition table scan:
>>   MBR: protective
>>   BSD: not present
>>   APM: not present
>>   GPT: not present
>
> If you have seen my recent thread,

I saw it, but did not read it in depth, because I had the impression, it is 
mainly about EFI systems. I'll re-read it ...

> much of this automounting during
> boot(strapping) is flaky that is much of what I have been searching out
> is a default (magical) partitioning schema that will eventually lead to
> clear documents on the current state of affairs not only with old versus
> new motherboards (mbr-->efi) and disk (mbr < 2.2T and gpt >2.2T)
> but including all sorts of new arm and other embedded (linux) boards.
>
> Different forms of Solid State memory are next on my list, with usb (1.x
> --> 3.x) being top of the SS memory mediums..... (Sorry I do not have
> more atm).
>
>> Creating new GPT entries.
>> Disk /dev/sdi: 732566646 sectors, 2.7 TiB
>> Logical sector size: 4096 bytes
>> Disk identifier (GUID): 80C04475-9B51-4A44-A52F-1F165AE02695
>> Partition table holds up to 128 entries
>> First usable sector is 6, last usable sector is 732566640
>> Partitions will be aligned on 256-sector boundaries
>> Total free space is 732566635 sectors (2.7 TiB)
>>
>> Number  Start (sector)    End (sector)  Size       Code  Name
>> ======================== %< ========================
>>
>> However, it's mounted successfully, see system logs:
>>
>> ======================== %< ========================
>> [22735.626752] sd 13:0:0:0: [sdi] 732566646 4096-byte logical blocks:
>> [(3.00
>> TB/2.73 TiB)
>> [22735.629255]  sdi: sdi1
>> [23414.066315] EXT4-fs (sdi1): mounted filesystem with ordered data mode.
>> Opts: (null)
>> ======================== %< ========================
>>
>> Has anyone ever tried the recovery option of GPT disk to rebuild GPT from
>> MBR?
>
> I see some sort of 'auto correction' by gpt technology to convert many
> forms of perceived mbr to gpt to be used by the booting process for
> spinning rust. So this issue is not limited to usb medium. I would also
> point out that I'd look deeply into the usb specs for the vendor of your
> usb sticks, as they do some 'funky things' at the firmware level inside
> many of the newer/faster/larger usb devices. It not just dumb memory
> like the early 1.x devices. Many are slanted to Microsoft business
> strategies. I'm not suggesting that is your current issues. I'm merely
> pointing out that some newer usb sticks are systems themselves complete
> with firmware so the devices looks like dumb memory. Furthermore, the
> silicon vendors provide firmware options to usb sticks vendors (like
> Texas Instruments) but also the vendor add to or change the hidden
> firmware as meets their multifaceted business objects. Sadly, the NSA is
> deeply involved here, as are many nation states and large corporations.
> You'd be surprised what youd find in a modern usb stick, should you take
> it into a class 6+ clean-room for analysis. The lower the particle count
> the more fantastic the tools
> to open up silicon and look deeply into what is actually going on.
> This is why folks love those classified research facilities that have
> govt contract and folks hanging around. Lots of very, very cool toys
> you just do not hear about...... Way beyond microscopes built by
> physicist.....

Actually it is not that modern. ~5 year old Intenso 2GB. I'd be surprised if 
booting from the stick prevents partition detection of another USB drive, 
but who knows? Maybe I should burn the iso instead and boot that one ;-)

> Prolly not your issue, but still present. Cheap ass usb vendors often
> have corner issues that are unintentional, that is why well recognized
> vendors of SS memory are the best to deal with, for consistency of
> behavior.
>
> I'd use as many different tools as you can find and read the vendor &
> silicon manufacturer's docs to see what you are really dealing with to
> ferret out this weirdness. (it's a darn time sync, just so you know).
>
>
> [1] http://www.cleanroom.byu.edu/particlecount.phtml
>
> hth,
> James

Thanks,
Jörg