I bought a 3.5-inch Toshiba HDWQ140 server class (N300) 4 TB drive on Amazon. I followed instructions to put it into service as the primary storage disk in my 6-year-old TiVo Bolt DVR.
I succeeded in formatting and configuring it using some TiVo-specific, 3rd-party software (centered around MSFtools). All is working as expected, now with greatly increased storage capacity.
One of the last things I did was to wave a strong magnet over the top of the drive mechanism. Believe me, I didn't plan to do this. I was using a strong magnetic-base flashlight near the TV and almost attached the flashlight onto the HDA. It didn't "click" onto the drive, but I felt the strong pull of the magnet toward the mechanism (the cover is stainless, I believe, so the pull wasn't toward that), and pulled away just in time—I hope. My hand, holding the flashlight, didn't stop, it just passed over the drive, almost being pulled onto the HDA.
I put the drive into the TiVo and so far, the TiVo hasn't flinched. All seems OK. But I think any damage depends on how storage is arranged. If the servo information is on the top platter, I think I'm safe, because if the magnet damaged this surface the drive would be dead now, or showing symptoms. If data is written (I presume this is true) in successive cylinders (the innermost tracks constitute cylinder 0; the next tracks are cylinder 1; then cylinder 2, etc.), then any damage to the top platter would affect all cylinders, and therefor all data. I think I'd be seeing some symptoms by now.
If my understanding of data storage is correct, any anomaly caused by my magnet would show up immediately, because all data is written to successive cylinders on all platters. I think I would have damaged all data on the drive.
I pulled out the drive from the TiVo and did a read-only badblocks scan; it took 6 hours and found no errors:
badblocks -vs /dev/hdb
Less than 5% of the drive's capacity is being used presently.
Do you think I’m safe? Would you place the drive in service or replace it?
Thanks.
EDIT: I replaced the small, mealy magnets on this flashlight with one of these. It's strong:
https://www.amazon.com/s?k=ASIN+B074BP1FR8&i=industrial&ref=nb_sb_noss