pendrive clone impossible ?

[Tomasz CEDRO]

On Sun, Dec 1, 2019 at 3:03 AM Anatoly  wrote:
> I've had a problem in the past with one of the first 32GB pendrives.
> Not quite similar problem, but may it be buggy RAM cache
> implementation too? What if:
> - Write sector(s)
> - usbconfig -d <your_bus>.<your_dev> power_off
> - usbconfig -d <your_bus>.<your_dev> power_on
> - Read and compare.
>
> As you saying some writes was succeful, some not. May it
> depend not on source of that bytes or their content, but on time passed
> between write and read?
>
> It turns out that Transcend pendrive I've got in 2010 had RAM cache
> (didn't remember exact cache size I measured out, as I remember
> something around 128K-512K), and all writes was cached. This amazingly
> speeds up random R/W fs operations in comparation with similar
> pendrives of those years, but I constantly losing the data and getting
> fs corrupted when used it with OSes that do not "power_off" or
> "suspend" that drive before I pull of it out of the socket.

The first pendrive is physically smaller Kingston slower and more
expensive. The second Kingston (the one with write problems) is
physically bigger 30% cheaper and a bit faster (50% read, 10% write,
but not as advertised 2x read, 4x write). If its cheaper and faster
then Kingston is bullshitting their clients. Also one of their workers
admitted that they have various vendors of flash controllers and
different firmware among them. so their products looks more like a
lottery. Not cool.

Thank you Anatoly! It looks then like a pendrive faulty tricky design
to fool users with exaggerated read/w/rite speeds.

-- 
CeDeROM, SQ7MHZ, http://www.tomek.cedro.info