Guide is a bit old & had some info that may not be relevant to scale. From my old notes on this:
Force badblocks *expect at least 4 days for 8TB drives
- Open tmux which will allow a new console per disk
• tmux- run badblocks per disk; following sets –c for multiple blocks tested at once (it won’t go past what drives allows but may use more ram & gives some speed benefits over default). –b for blocksize of the disk (4096 >2TB, don’t use for for <2TB, high volume at like 20tb could be higher)
• badblocks -c 2048 -b 4096 -wvs /dev/adaX- new tmux windows by “ctrl+b” then push the quotation mark “
- repeat as needed
- to view in things like Truenas go ‘tmux attach’
Backblocks will write on every possible sector of the HDD then read to confirm it did so successfully in several passes using different write patterns (think of it like memtest, but for your crazy slow HDDs). This’ll assure that every possible block of your HDD is actually proven to work prior to putting your precious data on it; good practice.
DO NOT USE BADBLOCKS ON ANY DRIVE THAT YOU ALREADY HAVE ON A POOL. DO NOT USE IT ON ANY DRIVE WITH DATA YOU WISH TO KEEP (though there are non-descrutive read-only ways of using it, I feel that they kinda defeat the purpose of badblocks entirely). BE VERY CAREFUL RUNNING BADBLOCKS ON ANY SYSTEM THAT HAS ANY DATA YOU WANT TO KEEP (you never know when your system random decides that ‘sda’ should be ‘sdb’ instead after a reboot & your badblocks command hits the wrong drive).
This will take a considerable amount of time (you quoted 2 weeks earlier; depending on the size of the drive doing smart long, full badblocks, then another smart long; it is entirely possible to take 2 weeks).