what is 'erase block' in the mkfs.jffs2 utility?
I couldn't find anything by googling, maybe because of my deficient search skills. Can anybody tell me what it is?
Can anybody can describe what 'erase block' is?
JFFS2 runs on raw flash, not on devices like USB sticks that have firmware that makes them look like traditional disks. Raw NAND flash can only erase (i.e. set bits to 1) in very large blocks. The "erase block" is the size of a block that the device can erase.
Look in /proc/mtd to see what your system thinks each device's erase block size is. (You'll need an MTD (memory technology device, i.e. raw flash) device to use /proc/mtd and for JFFS2 to be useful.)