On Fri, Aug 4, 2017 at 12:36 PM, Al Kossow via cctalk <cctalk@classiccmp.org > wrote:
> > > On 8/4/17 11:14 AM, Warner Losh via cctalk wrote: > > most SD cards can easily handle 100-200 writes > > The issue would be things like the swap partition on a unix disk > or whatever the equivalent is under RSX > Right. But since Flash devices have a FTL that translates writes to new locations in the NAND each time a logical block is written, there's no issue here. This issue with swap hasn't been an issue with NAND flash since early ~8MB CF cards (which is now almost 20 year old technology). I have a lot of miles using CF and SD cards in embedded systems, using both commercial grade and industrial parts since 2000 or so. I find it hard to believe that RSX could generate 128GB of data enough times, even in a swapping environment, to wear a card like that out. Even a more modest 8GB would take a while to wear out under 100% write workload, which swapping never is (since there's always readback for at least some of the pages swapped out). Though I did base my computations on 1MB/s being the fastest that Q-Bus can go, but that was my remembered performance from 3 decades ago since I couldn't find an answer to that question with a quick google. I shipped systems that were 100's if not 1000's times faster than the pdp-11's that could generate much more data traffic to SD and CF cards, and had very very few CF cards wear out. SD cards when we shipped needed to be not the smallest capacity on the market to do well and even there only a few cards wore out while I was doing this with them... Warner
