> On Aug 4, 2017, at 1:27 PM, ben via cctalk <cctalk@classiccmp.org> wrote: > > On 8/4/2017 12:49 PM, Warner Losh via cctalk wrote: >> 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 > > With everything @ 3.3 volts, you might as well use a ram dick cache > and back up dirty blocks on power fail, or power down, or reboot, as > a small battery would last forever, while main system is down. > >
Use MRAM (non-volatile) and behaves just as well as SRAM. That way you don’t have to deal with the battery issues. TTFN - Guy
