[GTALUG] Compressing an image of a microSD card

[D. Hugh Redelmeier]

| From: Lennart Sorensen via talk <talk at gtalug.org>

| If the filesystem is ext based, zerofree is a nice tool to zero unused
| space that seems to run faster than using dd and rm with a zero filled
| file.

If your filesystem lives on some form of flash (SSD, SD card, USB
stick, ...) this can reduce the lifetime and performance of your
hardware.

The wear-levelling firmware of the drive will think that every block of 
the drive is "live" (contains valuable information).  This will increase 
"write amplification".

In any case, if you do do this, be sure to use fstrim afterwards.  (I'm 
not sure that SD cards and USB sticks support trim.