@luz 'MTD and eraseblocks' I wanted to say: maybe you should calculate the lifetime with eraseblocks (xx KBytes) instead of flash pages (256 Bytes) and you should take into account only a part of the chip. So at least at the mtd layer, it is operating with 64kB (0x10000) erase blocks. Thanks! I've forgotten - I had already read this in the OpenWrt documentation. It seems I'm getting older... Maybe I should write everything down.