USB Flash Slice Wear Leveling

  • Running pfSense on 4GB USB Flash Drive.  The flash drive is split into 2 slices, da0s1 and da0s2, and slice 2 is a duplicate image of slice 1.

    While pfSense is running on slice 1, will wear leveling be done across the entire device or just the portion allocated to slice 1?  So that when slice 1 dies, slice 2 would still be good with full life left?

  • Netgate Administrator

    As I understand it wear leveling, if there is any on a usb drive, is independent of formatting so it will be across the entire drive.


  • Hoping then that this device does not wear level.  Only a $5 stick so maybe there's a pretty good chance of that.  Or that if it does wear level that somehow it manages to be within the slice.

    Was running on slice 2 for about the last 6 months and some static files recently started becoming corrupted.  Such as html and php files in the web directory.  Opened them up and though mostly intact there would be a few bytes here and there that were junk.

    Booted to slice 1 and restored a known good backup config.  So far seems okay.

  • I don't think any consumer USB flash drives have wear leveling, but even then, what difference would it make? Wear leveling would obviously not affect stationary data, so there's no way it would corrupt anything on the dormant slice.