[LoneTech]

In order to test the hypothesis that the pocketbook isn't actually writing all the data it receives, I tried copying the entire contents of my unclassed 2GB card using both a card reader and the 903.

Using only a card reader:
2003304448 bytes (2.0 GB) copied, 2324.63 s, 862 kB/s
The write speed was jumping around quite a bit, usually staying about 1MB/s but peaking about 3.3MB/s.
Using PocketBook 903:
The write speed clearly showed buffering going on, as the device would accept several megabytes (44MB in 3s was observed) from time to time, and nothing at all in between.
The first test failed, with some worrying messages from the kernel (after these came hundreds of errors because the device was gone):
[828350.358282] usb 2-1.5: reset high speed USB device using ehci_hcd and address 45
[828355.432875] usb 2-1.5: can't restore configuration #1 (error=-110)
[828355.433130] sd 24:0:0:1: Device offlined - not ready after error recovery
[828355.433143] sd 24:0:0:1: [sdc] Unhandled error code
[828355.433147] sd 24:0:0:1: [sdc] Result: hostbyte=DID_ABORT driverbyte=DRIVER_OK
[828355.433153] sd 24:0:0:1: [sdc] CDB: Write(10): 2a 20 00 10 8d c8 00 00 f0 00
Second test also failed. The device simply fails after some time. Before the failure, it appeared to copy a lot of data:
1212235776 bytes (1.2 GB) copied, 168.922 s, 7.2 MB/s
But as earlier indicated, that much couldn't have gone into the SD card that fast, not even if we count the device RAM as cache.

It is clear there's a failure detected in the PocketBook as well, and this is why it gets removed. I can't get at the internal diagnostics, though, as the terminal for earlier devices doesn't work on the 903.