On Mon, Dec 04, 2017 at 11:41:56AM +0000, Kevin Chadwick wrote: > On Mon, 04 Dec 2017 06:22:17 -0500 > > > > > > > > > We like booting from the SD, but they have none. > > > > > > How do you manage flash wear? Set up mfs all over the place? I much > > > prefer and need SATA anyway. > > > > > This might have been an issue 20 years ago. > > It is not any more. > > Please stop spreading FUD. > > I assume SD means microSD or something other than SSD. If not I > apologise. > > The latest atom boards come with 16-64 GB emmc onboard. > Apparently emmc may? perform wear levelling, SD would not unless you > pay a fortune for a special SD card. There seems to be a lot of > misinformation in this area which is quite dangerous considering what > some of these devices may be used for. > > http://eu.mouser.com/new/Swissbit/swissbit-industrial-SD-memory/ > > There are special embedded filesystems (often pay for) that do wear > leveling for standard SD, not sure if they reserve 20% of the space.
In my experience, even the cheap microsds from big brands support some type of wear leveling. The "industrial" labels in the microsds are only related to the temperature tolerance. Almost every BSD/Linux filesystem will kill your microsd pretty quickly, even in controllers/cards with support for ERASE. The exception is F2FS which allows to reserve a big part of your card as overprovision. I always prefer any type of external card instead of a emmc, because in the case of you break the card, you can simply change it. You can't change the emmc without soldering a new one in the board. > > I am fairly sure even emmc does not reserve 20% like sandforce/SSD > does and so a full filesytem could fail quickly. Perhaps an unused > partition could solve that?? > Modern SSDs don't reserve the 20%. The overprovisioning is very small. -- Juan Francisco Cantero Hurtado http://juanfra.info
