I downloaded an Ubuntu iso file through a binhex-delugevpn app. The resulting download has a single bit flipped.

Timeline:

Since 2017, there have been 51 parity checks. Only one had any errors in 2017 after an unclean shutdown. All other parity checks have 0 errors.

• Aug 2nd: parity check (no errors)

• Aug 13th: iso downloaded via torrent

• Aug 19th: bit flip noticed after checking against sha256 sum, parity check initiated

• Aug 20th: parity check finished (no errors)

I have resisted clicking "Force Recheck" on the torrent in the deluge UI because I suspect it will notice a bad chunk and correct it.

I wanted to leave it in this broken state to come here and ask if there is something else I should try before doing so.

Because there are no errors I should assume that this is not bit rot and maybe some other corruption occurred during various moving of the data?

Deluge settings for that download:

• Download folder: /data/incomplete (/mnt/user/download - cache: yes)

• Move Completed folder: /isos (/mnt/user/isos - cache: yes)

So my understanding would be:

• deluge downloaded the data into a cache enabled volume (/data/incomplete)

• deluge moved it to another cache enabled volume (/isos)

• Unraid's mover moved it from the cache to the array

I'm not sure at what point deluge verified the torrent. Perhaps after download and before moving? Maybe it doesn't verify the entire checksum but just the chunks?... not sure.

Is there anything else I should check?

What do you suspect happened?

Can I be fairly confident I have no bit rot because there were no parity check errors?

27 minutes ago, eric.frederich said:

What do you suspect happened?

Can I be fairly confident I have no bit rot because there were no parity check errors?

Probably just an error in transmission, parity was written with what it was sent - a corrupted file, so if all the 0's and 1's are in the right spot there are no errors in parity.

Bit rot is when a bit on the drive is flipped randomly over after time, which is unlikely. More likely is dodgy RAM sends the wrong bit to storage on write, or sends the wrong bit to the CPU on read.

Thanks... not sure that makes me feel any better though ;-)

Thankfully I'm getting a new NAS sometime soon (it's on a slow boat from China).

Minisforum N5 NAS Pro with ECC RAM.

Mayne this is something ECC RAM would have fixed?

15 hours ago, eric.frederich said:

Mayne this is something ECC RAM would have fixed?

Possibly, but only if the error happened in memory.