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02-07-2020, 05:29 AM
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#1
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Member
Registered: Aug 2010
Location: Brisbane, Australia
Distribution: Gentoo, Slackware, PCLOS, Debian
Posts: 230
Rep:
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Caveat emptor 128GB USB sticks
Further to my recent post regarding 128GB USB sicks (and the VERY embarrassing 'SOLVED' due to my forgetting to create filesystems after using fdisk - call me a geriatric if you will) I've news rather more interesting to report.
To recap briefly, I purchased five cheap ($7) Chinese 128GB USB sticks for use initially as temporary secondary backup devices to evaluate them. My first requirement was to backup a commercial 128GB USB stick in order to safeguard my $70 investment. I assumed that the manufacturer may have used some sort of anti-copy protection similar to that on DVDs, so wasn't surprised when the first attempt failed. The second attempt used a second of the new sticks with similar results.
I then moved to the second requirement, to reformat a stick with two 16GB ext4 partitions and a single 96GB ext4 partition for the remainder. This appeared to be successful since the two 16GB partitions mounted successfully, but the third gave a "bad partition" error. This got me suspicious, so I fdisk'd the remaining two new sticks, only to find, not the single NTFS partition I'd expected, but:
Code:
qtm:~># fdisk /dev/sdd1
Welcome to fdisk (util-linux 2.33.1).
Disk /dev/sdd1: 125 GiB, 134217711616 bytes, 262143968 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000
Device Boot Start End Sectors Size Id Type
/dev/sdd1p1 4294967295 8589934589 4294967295 2T ff BBT
/dev/sdd1p2 4294967295 8589934589 4294967295 2T ff BBT
/dev/sdd1p3 4294967295 8589934589 4294967295 2T ff BBT
/dev/sdd1p4 4294967295 5035196669 740229375 353G ff BBT
qtm:~>#
The three BBT partitions sized at 2TB - ??? - plus a fourth smaller BBT suggest that the device is in fact a "composite storage unit" of some sort. My deduction is that some - perhaps all - "128GB" USB sticks consist PHYSICALLY of 4 x 32GB memory cells "tied together" by a "management unit" that makes them appear as a single 128GB device. REFORMAT THIS AT YOUR PERIL!!!
Further experimenting with the initial two sticks confirmed something very strange going on. I first attempted a standard repartition into a single XFAT partition, but this failed on both. I then used the standard "trick" of wiping the first few megabytes of the device:
Code:
qtm:~># dd if=/dev/zero of=/dev/sdd bs=4M count=1000
dd: error writing '/dev/sdd': No space left on device
474+0 records in
473+0 records out
1985966080 bytes (2.0 GB, 1.8 GiB) copied, 2.4177 s, 821 MB/s
qtm:~>#
... so dd could only find 2GB of storage on the device. Attempting to write a partition table then gave:
Code:
qtm:~># fdisk /dev/sdd
Welcome to fdisk (util-linux 2.33.1).
Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0xb375fedc.
Command (m for help): o
Created a new DOS disklabel with disk identifier 0xa7c1ff84.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p):
Using default response p.
Partition number (1-4, default 1):
First sector (2048-3878839, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-3878839, default 3878839):
Created a new partition 1 of type 'Linux' and of size 1.9 GiB.
Command (m for help): q
qtm:~>#
In other words, the "128GB USB stick" is now a 2GB device, and I've no idea how to change this.
All suggestions appreciated.
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02-07-2020, 07:48 AM
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#2
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LQ Guru
Registered: Mar 2016
Location: Harrow, UK
Distribution: LFS, AntiX, Slackware
Posts: 8,133
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We had a thread on this sort of thing some time ago. Apparently a lot of ultra-cheap sticks bought online have only a fraction of the memory they are supposed to have. Basically it's a scam. If you use them for backup and then need to do a restore, you'll find that most of the dump isn't actually there.
See for example https://www.linuxquestions.org/quest...nt-4175649723/
Last edited by hazel; 02-07-2020 at 07:54 AM.
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3 members found this post helpful.
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02-07-2020, 09:05 AM
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#3
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LQ Guru
Registered: Sep 2011
Location: Upper Hale, Surrey/Hants Border, UK
Distribution: One main distro, & some smaller ones casually.
Posts: 5,774
Rep: 
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Try deleting all partitions, create a new mbr, create a new partition, & see how big it says it is.
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1 members found this post helpful.
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02-07-2020, 09:15 AM
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#4
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LQ Guru
Registered: Sep 2013
Location: Somewhere in my head.
Distribution: Slackware (15 current), Slack15, Ubuntu studio, MX Linux, FreeBSD 13.1, WIn10
Posts: 10,342
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cheap ($7) Chinese 128GB USB sticks : the ole if it is too good to be true then ... proverb should be applied here.
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1 members found this post helpful.
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02-07-2020, 09:50 AM
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#5
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Senior Member
Registered: Aug 2011
Location: Dublin
Distribution: Centos 5 / 6 / 7 / 8
Posts: 3,550
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Sandisk 128Gb USB 3.0 sticks are on Amazon for around $20, so I'm sure there will be knock-off 4Tb USB keys coming along for $10 soon! 
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02-07-2020, 04:50 PM
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#6
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Member
Registered: Aug 2010
Location: Brisbane, Australia
Distribution: Gentoo, Slackware, PCLOS, Debian
Posts: 230
Original Poster
Rep:
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> if it is too good to be true then ... proverb should be applied here.
True enough, but sometimes investigating is the only way to know what's happening. Thing is, the original format does seems to be there, although I haven't yet tested this; but reformatting definitely screws things up good and proper.
> We had a thread on this sort of thing some time ago.
Looked it up and it seems to confirm my deductions. Didn't know that there WERE terabyte USB sticks, but his complaint about them is very similar to mine.
HOWEVER, he DOES report success reformatting 128GB sticks. My guess continues to be that the quality sticks can be reformatted and repartitioned like a standard block device, but that the cheaper ones that DO work cannot be reformatted for the reasons I've given above.
Looks like we need a list of real and fake USB sticks in the hardware section. If my fdisk report above is correct, this may be the best way to distinguish them.
Last edited by tekra; 02-07-2020 at 04:53 PM.
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02-07-2020, 05:14 PM
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#7
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Senior Member
Registered: Aug 2009
Distribution: Rocky Linux
Posts: 4,804
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Quote:
Originally Posted by tekra
Code:
Disk /dev/sdd1: 125 GiB, 134217711616 bytes, 262143968 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000
Device Boot Start End Sectors Size Id Type
/dev/sdd1p1 4294967295 8589934589 4294967295 2T ff BBT
/dev/sdd1p2 4294967295 8589934589 4294967295 2T ff BBT
/dev/sdd1p3 4294967295 8589934589 4294967295 2T ff BBT
/dev/sdd1p4 4294967295 5035196669 740229375 353G ff BBT
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Quote:
Originally Posted by tekra
True enough, but sometimes investigating is the only way to know what's happening. Thing is, the original format does seems to be there, although I haven't yet tested this; but reformatting definitely screws things up good and proper.
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That "original format" looks like what would be printed for a partition table filled with 0xff bytes instead of zeros. Take a look with hexedit or hexdump.
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1 members found this post helpful.
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02-07-2020, 05:29 PM
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#8
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Member
Registered: Apr 2018
Location: Delden, NL
Distribution: Ubuntu
Posts: 261
Rep: 
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Quote:
Originally Posted by tekra
Looks like we need a list of real and fake USB sticks in the hardware section. If my fdisk report above is correct, this may be the best way to distinguish them.
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Normally this would be a nice idea. However, I've been to China and can report that they have a gazillion number of names for the same stuff. You can make a list as long as you can imagine, it will never be comprehensive.
Normally I am happy to order from China. Most of the times I get OK things. However I have heard and seen so much bad things with bad SD cards and bad USB sticks, I now avoid these at all cost. Even watched a video from someone who had bought a "1 TB USB drive" for $ 7. Of course it did not have 1 TB of space. It did have malware on it that deleted all data from the Windows test system (pun intended).
So if I need a USB key I just go down to the local computer store and buy one.
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02-07-2020, 05:46 PM
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#9
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Member
Registered: Aug 2010
Location: Brisbane, Australia
Distribution: Gentoo, Slackware, PCLOS, Debian
Posts: 230
Original Poster
Rep:
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> looks like what would be printed for a partition table filled with 0xff bytes instead of zeros. Take a look with hexedit or hexdump.
Good suggestion. As you can see, it's reported as a fuseblock FS with 4096 block size, so I used dd to read the first two into a file:
Code:
qtm:~># m
/dev/sdd1 on /media/root/76E8-CACF type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096,uhelper=udisks2)
qtm:~># dd if=/dev/sdd of=USB-128GB bs=4096 count=2
2+0 records in
2+0 records out
8192 bytes (8.2 kB, 8.0 KiB) copied, 0.0016364 s, 5.0 MB/s
qtm:~># ll U*
-rw-r--r-- 1 root root 8192 Feb 8 08:55 USB-128GB
qtm:~># hd USB-128GB
00000000 fa 33 c0 8e d0 bc 00 7c 8b f4 50 07 50 1f fb fc |.3.....|..P.P...|
00000010 bf 00 06 b9 00 01 f2 a5 ea 1d 06 00 00 be be 07 |................|
00000020 b3 04 80 3c 80 74 0e 80 3c 00 75 1c 83 c6 10 fe |...<.t..<.u.....|
00000030 cb 75 ef cd 18 8b 14 8b 4c 02 8b ee 83 c6 10 fe |.u......L.......|
00000040 cb 74 1a 80 3c 00 74 f4 be 8b 06 ac 3c 00 74 0b |.t..<.t.....<.t.|
00000050 56 bb 07 00 b4 0e cd 10 5e eb f0 eb fe bf 05 00 |V.......^.......|
00000060 bb 00 7c b8 01 02 57 cd 13 5f 73 0c 33 c0 cd 13 |..|...W.._s.3...|
00000070 4f 75 ed be a3 06 eb d3 be c2 06 bf fe 7d 81 3d |Ou...........}.=|
00000080 55 aa 75 c7 8b f5 ea 00 7c 00 00 49 6e 76 61 6c |U.u.....|..Inval|
00000090 69 64 20 70 61 72 74 69 74 69 6f 6e 20 74 61 62 |id partition tab|
000000a0 6c 65 00 45 72 72 6f 72 20 6c 6f 61 64 69 6e 67 |le.Error loading|
000000b0 20 6f 70 65 72 61 74 69 6e 67 20 73 79 73 74 65 | operating syste|
000000c0 6d 00 4d 69 73 73 69 6e 67 20 6f 70 65 72 61 74 |m.Missing operat|
000000d0 69 6e 67 20 73 79 73 74 65 6d 00 00 00 00 00 00 |ing system......|
000000e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000001b0 00 00 00 00 00 00 00 00 33 b8 2c fa 00 00 80 01 |........3.,.....|
000001c0 01 00 07 fe ff ff 20 00 00 00 e0 ff 9f 0f 00 00 |...... .........|
000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.|
00000200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00002000
qtm:~>#
Been a long time since I worked with MBRs etc, but the part'n tab should be in the first 512 bytes. Anyone who knows/remembers the offsets might be able to throw light on the above, but sorry, doesn't look like all FFs.
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02-07-2020, 05:55 PM
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#10
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Member
Registered: Aug 2010
Location: Brisbane, Australia
Distribution: Gentoo, Slackware, PCLOS, Debian
Posts: 230
Original Poster
Rep:
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> Normally this would be a nice idea ...
You're quite right. My concern is that I'd thought of making a "Debian on a stick', but rather than using the small ones as usually recommended, I was thinking of 128GB as being useful for real work. The Deb site gives a list of "Standard Pendrives":
https://wiki.debian.org/StandardPendrive
... but this dates from 2014. Perhaps a list of recommended manufacturers - esp. for Newbies etc - would be short, feasible and could be tested at various sizes.
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