The device is a 'Fission' branded 8Gig USB stick. Fission is a registered trademark of Aldi Stores.
The first USB stick was DOA. Although the OS detected something, no actual drive was found. The second stick showed symptoms comparable to the same model owned by another family member (bought from an Aldi store in a different location).
First symptoms:
- Some files appear not to work properly (in this case AVI files).
- Some files appear to be missing from the directory after they were copied.
- Writing files is terribly slow.
The USB stick was reformatted in preparation for more rigorous testing. First, a 100MB file of random data was created and then copied across to the USB stick as discreet files until the filesystem was full. Using the 'direct' flag with dd circumvents OS buffering, giving us a more accurate average write speed: 1.6 MB/s. DirectIO can degrade throughput for small block sizes, so we use 1MB here.
$ dd if=/dev/urandom of=./testfile bs=1M count=100
...
$ for i in `seq -w 0 85`; do
> dd if=./testfile of=/media/New\ Volume/testfile.$i bs=1M oflag=direct
> done
...
104857600 bytes (105 MB) copied, 66.1858 s, 1.6 MB/s
...
This created 80 files, the last one truncated, and five zero byte files as the space was exhausted. Testing one file for read using dd shows an average read speed of 8.0MB/s.
$ dd if=/media/New\ Volume/testfile.00 of=/dev/null bs=1M iflag=direct
...
104857600 bytes (105 MB) copied, 13.0471 s, 8.0 MB/s
Finally the file content was checked with md5sum.
$ md5sum testfile /media/New\ Volume/testfile.*
Only the first 62 files were checked, the rest had disappeared. Each file had a unique checksum. None of them were the same as the original. On un-mounting , removing the device, re-inserting and re-mounting, the test was repeated. The same 62 files existed, all but one repeated same unique (but incorrect) checksum. Listing the filesystem contents showed directory corruption.
At this point the device had stopped being writable and could not be reformatted or erased.
As a comparison, a new Kingston DataTraveler 16Gig was used.
$ dd if=/dev/urandom of=./testfile bs=1M count=100
...
$ for i in `seq -w 0 160`; do
> dd if=./testfile of=/media/KINGSTON/testfile.$i bs=1M oflag=direct
> done
...
104857600 bytes (105 MB) copied, 8.13906 s, 12.9 MB/s
...
$ dd if=/media/KINGSTON/testfile.000 of=/dev/null bs=1M iflag=direct
...
104857600 bytes (105 MB) copied, 3.83913 s, 27.3 MB/s
There were no errors in any files tested with the Kingston USB stick.
As a final note, Aldi Australia were selling the Fission 8Gig stick for $15.99, and MSY were selling the Kingston 16Gig stick for $25.00.
