You can also use the 'f2fs' as filesystem on your sd-card. Things become rather slow (as it is a logging filesystem) but I used the same card for more over 5 years in a frontdoorcamerasystem I wrote and made.
On Wed, Dec 08, 2021 at 02:43:47PM -0800, Kevin Rowett wrote: > Jim, > > The wear leveling algorithms have gotten very good at garbage collection, > wear leveling, and bit error recovery codes. (LDPC has gotten a lot of > practical research for flash). > (the challenges are - when to do the garage collection, so as not to impact > read and write rates, yet not run so low that write IOP rate falls off a > cliff, AND still keep pages alive). > > File systems that try to understand the flash sectors generally haven???t > proven as helpful as the flash device controller wear leveling algorithms. > > A lot of the SD cards have gone to TLC style memory (also know as trash). > > KR > > > > On Dec 8, 2021, at 2:35 PM, Lux, Jim <[email protected]> wrote: > > > > On 12/8/21 2:15 PM, Bill Dailey wrote: > >> You can also set them up so they don???t write to the SD once everything > >> is set. SD???s will last forever like this. Basically read only and RAM > >> disk. > > > > > > yes indeed - these days, with lots o'RAM on a rPi, you should boot off the > > SD (or eMMC) and run out of RAM. For a "clock" application, you could > > probably structure your writes to SD (for nonvolatile storage of logs, > > etc.) so that you limit the number of writes. If you log once an hour > > that's just under 9000 writes/year. > > > > Typical MLC flash is good for at least 10,000 erase cycles on a page. > > Writing data to an erased page (or the part that's not already written) > > doesn't wear it out, but changing data in the middle of a file does, > > because you have to erase it (consuming life), and then rewrite. > > > > There are Journaling File Systems that deal with this, but I doubt they're > > compatible with the wear leveling systems in commercial SD cards. > > Basically, the SD card has a controller that exposes a generalized > > interface, with the wear leveling hidden from you, and if it's hidden, then > > the JFS doesn't really know how to manage the device. > > > > I don't know, though, it's a fertile ground - and someone may have a nice > > JFS for a common distro for RPi and SD card. > > > > > > If you want to get real down and dirty, there are also clever schemes that > > write all ones or zeros (depending on the device), instead of erasing, and > > then the reader of the file knows that this means "not used" - Much like > > the RUBOUT character on paper tape, or a similar scheme used with PROMS > > where you don't want to erase it. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] -- To unsubscribe send > > an email to [email protected] > > To unsubscribe, go to and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send an > email to [email protected] > To unsubscribe, go to and follow the instructions there. Folkert van Heusden -- www.vanheusden.com/multitail - multitail is tail on steroids. multiple windows, filtering, coloring, anything you can think of ---------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
