from /system resources

Write cycles 493325 bad blocks 0.1% RB951g-2HnD 2 weeks old. running 6.28

for NAND memory it is normal to have some bad sectors from the moment of production, if i remember correctly some manufactures even indicate approximate number of bad blocks on chip markings..

As long as this percentage is below few percent you are ok.
In any case NAND is used only for upgrades/ logging and some backup/supout.rif file writing/reading.

write-sect-since-reboot: 34625
write-sect-total: 4152666
bad-blocks: 0,1%
board-name: CRS109-8G-1S-2HnD

write-sect-since-reboot: 1041
write-sect-total: 2900920
bad-blocks: 0.1%
board-name: RB951G-2HnD

Unit has been in use for about 14 months.

how reduce bad? or cut bad space?

and why no bad Block count on CCR1009?

uptime: 33w4d5h57m44s
version: 6.10
cpu: MIPS 74Kc V4.12
free-hdd-space: 109.5MiB
write-sect-since-reboot: 203548
write-sect-total: 404999
bad-blocks: 0%
board-name: RB2011UiAS-2HnD

I believe the counter was reset after I upgraded ROS one time in total. I use graphing, saved to disk every 24 hours. Age is about 15 months.

Routerboard 532A had 3 bad sectors last time I looked at it. The value has stayed the same. The web proxy was enabled on it for a short period, disk writes are about 8 million.