Re: ssd from 4tb to only 2gb

Date	2025-03-17 07:54 -0400
From	bad sector <forgetski@_INVALID.net>
Subject	Re: ssd from 4tb to only 2gb
Newsgroups	alt.os.linux
References	<f46dnSdnpNRP61f6nZ2dnZfqnPgAAAAA@giganews.com> <vqfa38$3l50b$1@dont-email.me>
Message-ID	<9_6dnVhctfsXkEX6nZ2dnZfqnPWdnZ2d@giganews.com> (permalink)

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On 3/7/25 12:23, Paul wrote:
> On Thu, 3/6/2025 11:32 PM, bad sector wrote:
>> Posting this in case someone googles for it in desparation
>> ==========================================================
>>
>> I've seenm other makes of ssd's acting up to so it's probably not just my
>> Team Grp 4tbs although both incidents WERE with Team-Grp ssd's (have 2).
>> The first time it happened windows was not involved at all, not in the
>> cause nor in the undetermined solution. This last time a run in windows
>> was the only way out of the pits.
>>
>> After formatting with gdisk to a single 4tb ext4 1st partition I put it
>> away for a day or so, on ready-1 as it were. Today I try to use it and the
>> ssd is only 2gb in size! That's right, NOT 2TB but 2GB and I could not
>> find any linux solution that actually worked. So after reading some
>> similar horror stories I plugged it in under w10 disk-managment where it
>> was showing as a normal unused 4tb device. I reformatted it all as ntfs.
>> The next time in linux gdisk was showing the correct and full 4tb size
>> again.
>>
> 
> I can find a reference to this happening with a SATA device, so I'm
> guessing this isn't an NVME stick. You should list the model number
> in your post, in case that is important.



Sorry I missed yey another invaluable knowhow monument from esteemed 
Paul! I'm totally swamped these days and for maybe months to come but I 
will look it up and get back with the numbers ASAP :-)




> 
> There are several mechanisms to end up with a 2GB drive. The "obvious" ways
> are with a Host Protected Area (HPA) or a DCO. Not all hardware devices support
> that. On my (deceased) X48 system with E8400 processor, the Intel SATA ports
> do not allow the formation of an HPA. However, the JMicron IDE header, the
> driver in it *did* support HPA, and by fitting an IDE to SATA adapter, I
> could do an HPA on a SATA drive. Now that the X48 system is deceased, I can
> no longer do an HPA for experimental purposes.
> 
> On drives back around early 2000's era, there was a Clip Jumper on the drive.
> Insert that and it limits the disk size. (Don't worry, that jumper feature
> no longer exists on drives.) It doesn't really change the disk size,
> it changes some reported CHS value and the interpretation of that,
> is up to the OS you are running.
> 
> https://aeb.win.tue.nl/linux/Large-Disk-11.html
> 
>     11.4 Jumpers that clip total capacity
> 
>     Clip to 2.1 GB
>     --------------
> 
>     The first serious limit was the 4096 cylinder limit (that is, with 16 heads and 63 sectors/track, 2.11 GB).
>     For example, a Fujitsu MPB3032ATU 3.24 GB disk has
> 
>         default geometry 6704/15/63
> 
>     but can be jumpered to
> 
>         appear as        4092/16/63
> 
>     and then reports LBAcapacity 4124736 sectors, ... operating system cannot guess that it is larger in reality.
> 
>     Clip to 33 GB
>     -------------
> 
>     The IBM Deskstar 37.5 GB (DPTA-353750) with 73261440 sectors (corresponding to 72680/16/63, or 4560/255/63)
>     can be jumpered to appear as a 33.8 GB disk, and then reports geometry         16383/16/63 like any big disk,
>     but [reports] LBAcapacity 66055248 (corresponding to                           65531/16/63, or 4111/255/63).
> 
> That article also has an extensive section on individual company implementations,
> indicating the behavior wasn't exactly standardized. One thing IBM supported
> at the time (as an example of bad jokes), was sector sizes other than 512 bytes.
> Maybe the attraction at the time, was the soft-sectoring of drives and
> the existence of actual Low Level Format commands, make things like this
> possible, but it may not have actually been implemented that way. I vaguely
> recollect reading some disk drive specification document, with all these
> disquieting sector size options mentioned in passing.
> 
>     "The ATA Read Native Max and Set Max commands may be used to reset the true full capacity."
> 
>     [And that is with 48 bit LBA and double-pumped control and data register, so
>      should be able to handle disks over 2.2TB. It's the MBR value (32 bit address)
>      that "limits" disks to 2.2TB, rather than the drive itself having an addressing limit that low.]
> 
> *******
> 
> The good news is, it's none of those things :-) :-)
> 
> The clipping values, are not power-of-two. They're derived from weird CHS numbers,
> and the "small limit" is 2.11GB, whereas you report 2.00GB. Your limiting case
> could be an exact power-of-two value.
> 
> (This is one reason, when reporting weird capacity issues, it is a good idea
>   to report exact byte values such as seen in "disktype", "fdisk", or "gdisk".)
> 
> Someone suggests this is a secured storage facility of some sort,
> and maybe the drive either advertises such a mode or was left in
> that mode at the factory. Is it a manifestation of FDE (Full Disk Encryption) ?
> Dunno. If a partition had been "formatted" to a certain size, surely
> the mount command would have noticed the file system had no upper end.
> 
> There are capacity measurement softwares, but I have never tracked such a
> thing down and used it in anger. In the HDD days, I used to test drive purchases
> by "filling them with files, 1GB at a time", in order to detect canonical
> limit cases before they happened by accident. For example, one USENETTER
> writes in, has constructed a 3TB raid using three 1TB drives. He seemed
> rather proud of himself. OK, so he is ripping DVDs one at a time and filling
> the RAID. At the 2.2TB mark, the RAIDed volume instantly disappears. He
> has suffered a case of "address rollover at 2.2TB" and the MBR just got deleted.
> Did he have a backup ? Nope :-) This is why we *test* storage capacities
> to make sure we did not neglect a detail. Even though the software allowed
> him to make a 3TB volume, the software did *not* warn him that he was
> set up for a failure case.
> 
> In the old days, I was known for copying 1GB files onto a drive,
> until the drive was full, as proof the "drive actually had that
> much storage space". This was to prove, for a storage device,
> I had not hit some canonical limit described in the aeb.win.tue.nl URL above.
> 
> For example, one day, I was in a VM, and the manual says "we have a disk
> passthru mode". Great. I have a 200GB video I'm editing. Boom. Corrupted.
> Turns out the hardware interface used, had 28 bit LBA (not 48 bit LBA),
> and it managed to corrupt the real storage of the passthru drive.
> So so funny. Ha. The VM could not address more than 137GB, the address
> rolled over inside the VM, the VM was writing to the MBR, when it thought
> it was writing to 137GB + 1 sector as an address. And that instantly
> destroys the partition table. And why would you back up such a
> drive before such an experiment ? Shirley the mode is safe. Shirley.
> 
> *******
> 
> You should run "disktype" after this, because it can show the
> protective 0xEE partition declaration on a GPT disk. And you would
> need GPT for a 4TB storage device. This is my daily driver 4TB SATA SSD (GPT).
> 
> S:\disktype> disktype.exe /dev/sda            <=== cygwin disktype
> 
> --- /dev/sda
> Block device, size 3.639 TiB (4000787030016 bytes)
> DOS/MBR partition map
> Partition 1: 2.000 TiB (2199023255040 bytes, 4294967295 sectors from 1)
>    Type 0xEE (EFI GPT protective)        <==== Protective MBR, tells WinXP to "go away and don't come back"
>                                                The three other MBR partition entries are empty
> GPT partition map, 128 entries
>    Disk size 3.639 TiB (4000787030016 bytes, 7814037168 sectors)
>    Disk GUID CD4D6752-BAC8-B446-90A7-662721F0DD2D
> 
> Partition 1: 100 MiB (104857600 bytes, 204800 sectors from 2048)
>    Type EFI System (FAT) (GUID 28732AC1-1FF8-D211-BA4B-00A0C93EC93B)
>    Partition Name "EFI system partition"
>    Partition GUID BE145A8D-FC87-9B45-AFB1-8959CB4D727A
>    FAT32 file system (hints score 4 of 5)
>      Volume size 96 MiB (100663296 bytes, 98304 clusters of 1 KiB)
> Partition 2: 16 MiB (16777216 bytes, 32768 sectors from 206848)
>    Type MS Reserved (GUID 16E3C9E3-5C0B-B84D-817D-F92DF00215AE)
>    Partition Name "Microsoft reserved partition"
>    Partition GUID B000A1BB-661C-7541-AF97-88BB60627F66
> Partition 3: 118.7 GiB (127481675776 bytes, 248987648 sectors from 239616)
>    Type Basic Data (GUID A2A0D0EB-E5B9-3344-87C0-68B6B72699C7)
>    Partition Name "Basic data partition"
>    Partition GUID 6A16D60B-3608-4140-891C-792DF2C72ABD
>    NTFS file system
>      Volume size 118.7 GiB (127481675264 bytes, 248987647 sectors)
> Partition 4: 649 MiB (680525824 bytes, 1329152 sectors from 249227264)
>    Type Unknown (GUID A4BB94DE-D106-404D-A16A-BFD50179D6AC)
>    Partition Name ""
>    Partition GUID B15ABCC3-F0C5-AE4D-838C-751EF868E237
>    NTFS file system
>      Volume size 649.0 MiB (680521728 bytes, 1329144 sectors)
> Partition 5: 129.0 GiB (138510690816 bytes, 270528693 sectors from 250556416)
>    Type Basic Data (GUID A2A0D0EB-E5B9-3344-87C0-68B6B72699C7)
>    Partition Name "Basic data partition"
>    Partition GUID BC694DBD-BB6F-124F-B804-F32C6B9E828C
>    NTFS file system
>      Volume size 129.0 GiB (138510690304 bytes, 270528692 sectors)
> Partition 6: 1.001 GiB (1074790400 bytes, 2099200 sectors from 521086976)
>    Type Unknown (GUID A4BB94DE-D106-404D-A16A-BFD50179D6AC)
>    Partition Name ""
>    Partition GUID CF6B38AF-C016-3F48-A84B-B310CC27C8E8
>    NTFS file system
>      Volume size 1.001 GiB (1074786304 bytes, 2099192 sectors)
> Partition 7: 682.0 GiB (732331769856 bytes, 1430335488 sectors from 523186176)
>    Type Basic Data (GUID A2A0D0EB-E5B9-3344-87C0-68B6B72699C7)
>    Partition Name "Basic data partition"
>    Partition GUID DA97834F-DF61-974A-B913-9BD526C13C9A
>    NTFS file system
>      Volume size 682.0 GiB (732331769344 bytes, 1430335487 sectors)
> Partition 8: unused
> 
> That's just to show you the level of detail available. The report
> in GDISK, of "EF00", is shorthand for "28732AC1-1FF8-D211-BA4B-00A0C93EC93B",
> which is why the pseudo-codes were invented, to help humans. The
> value "EF00" is not written on the drive anywhere.
> 
>     Paul

Thread

ssd from 4tb to only 2gb bad sector <postit@invalid.org> - 2025-03-07 04:32 +0000
  Re: ssd from 4tb to only 2gb Paul <nospam@needed.invalid> - 2025-03-07 12:23 -0500
    Re: ssd from 4tb to only 2gb bad sector <forgetski@_INVALID.net> - 2025-03-17 07:54 -0400
    Re: ssd from 4tb to only 2gb bad sector <postit@invalid.org> - 2025-03-18 21:45 +0000
      Re: ssd from 4tb to only 2gb Paul <nospam@needed.invalid> - 2025-03-18 20:39 -0400

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