On Thu, Aug 8, 2019 at 12:51 PM ben <bfranc...@jetnet.ab.ca> wrote: > On 8/8/2019 12:26 PM, Warner Losh wrote: > > > Even the crappiest of crap SD cards these days aren't that fragile. > > You'd need to swap on the order of GB/s to wear it out that fast. Most > > of the SD cards can handle hundreds of full drive writes. At 128GB, > > you're looking at needing to generate about ~25TB of effective writes > > before you'd wear them out. Even with a crazy 10x write amp (typical is > > 2-3), there's no way you'd get that through an interface that's measured > > in the tens of MB/s. > > I would agree if it was doing a whole disk. > A swap or scatch space on magnetic media got used alot back then. > Time sharing back then was having 16KW and swapping pages back and forth > from rotating media while reading or writing cards. >
The NAND pool in the SD cards is rotated to do wear-leveling and to cope with the insanely large erase block sizes that we have these days, so the particular LBAs being re-scribbled doesn't matter, though you might get a lot of write-amp from doing 512-byte I/O when the underlying page size is 4kb or 16kb. Even so, it would take a lot... > > Warner > > I am not sure of the memory on a PI,but having a good block cache > for the swap segments on disk would useful. > Agreed. I don't think SIMH forces synchronous writes... A good buffer cache will mitigate this. I tried to wear our old CF cards w/o disabling the buffer cache and found it was impossible... But with disabling it, it was just barely possible, if you did the right things... > Well the CPU is the easy part. Now what about the front panel. :) > This is purely the dialup experience, eh? :) Warner > Ben. > > > >
