USB 3 claims Flash drive is already formatted in exFAT, let’s test its speed by writing « zeroed » files: $ for i in `seq 1 40`; do echo $i; dd if=/dev/zero of=f$i bs=1M count=1024; done 1 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 1.34213 s, 800 MB/s 2 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 3.06786 s, 350 MB/s 3 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 98.9574 s, 10.9 MB/s 4 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 119.99 s, 8.9 MB/s Write speed quickly drops to ~9 MB/s, USB 3 really?
storage capacity claim (1/2) A bit more difficult, have a look at our files headers: $ for i in `seq 1 2048`; do file f$i; done f1: data f2: data f3: data f4: data (...) f29: data f30: data f31: ISO-8859 text, with very long lines, with no line terminators f32: ISO-8859 text, with very long lines, with no line terminators f33: ISO-8859 text, with very long lines, with no line terminators f34: ISO-8859 text, with very long lines, with no line terminators f35: ISO-8859 text, with very long lines, with no line terminators (...) Curiously, something happens between f30 and f31...
on filesystems • On fake USB flash drives: – FAT and exFAT are well supported – EXT2/EXT3/EXT4: default formatting use superblock backups across all storage layout, these filesystems will be detected as corrupted
finally happened with my last purchase... • I made a complaint through Paypal • Vendor denied and asked for proofs, that’s why I writed this presentation • Was refunded because of no answer from the seller after my full report to Paypal
to avoid buying a fake one • Avoid chinese websites • Look for real/fake reviews • Used USB cases are always the same four or five ones! Train yourself to recognize them... • Prefer buying with Paypal who offers to reimburse you if the product doesn’t comply with its description • In case of doubt, test your key using my procedure!