On 8/4/2017 8:07 AM, Christian Corti via cctalk wrote:
On Fri, 4 Aug 2017, Noel Chiappa wrote:
But are SD cards really that unreliable? If they were, I'd have
thought I'd
Yes they are. Just have look around in the world of cameras and
smartphones where people suffer from losing their photos just because an
SD card decides to fail. I have several failed SD and CF cards, as well
as USB bars. And many flash cards will fall into a read-only mode when
errors cannot be corrected anymore, in contrast to real disk drives
where you can skip the bad areas.
I just had a look on some datasheets for industrial SD cards. ATP gives
a value of 384 TBW (terabytes written) for SLC and 38.4 TBW for MLC
devices. For a 32 GB SD card, this means a max. write count of 12,000
for a byte. SanDisk give 192 TBW for their Industrial XT, that is even
worse. A 64 GB SD card would only support 3000 writes per byte before
you begin to play roulette...
Soooo... here I come again with my preference of PATA/SATA drives. If
you really want a non-rotating media, then I suggest that you use SATA
SSDs.
Hence why I prefer a controller/interface with PATA/SATA connectors ;-)
You are totally free in using rotating or non-rotating media.
Christian
But where do find Industrial SD cards?
Even so, for most of DEC's PDP's they do so much core memory to disk
swapping of pages that better design to replace rotating media is needed.
Ben.
