TrueNas Core slow read

i have an home built TrueNas Core 13.0 server.
yesterday i got an alert:* Pool Main Pool state is ONLINE: One or more devices has experienced an
unrecoverable error. An attempt was made to correct the error. Applications
are unaffected

Then today i got another alert:
These alerts have been cleared:

  • Device /dev/gptid/066f963a-659a-11eb-b336-7824af3272cd is causing slow I/O on
    pool Main Pool.

i did a restart and some SMART tests and cant find any errors any more. but the server is extremely slow when i try to read from it. play a video is almost impossible and coppy files etc. with no new errors i have no ideah where to start. could it be that one drive in the second error that starts to give up?

Update: i did a SMART test on the drive and it Fails, get Error: 630447766
i guess the drive is on its way out?

Drives do no always produce smart error when they are going bad.

do you have any video on Alerts and troubleshooting for a Truenas? The alerts are awesome but it can be a bit tricky to know what they mean. Just to get the gptid to match with a drive was not to easy, did find a good script for it though.

in my case it must be the drive, did rip it out and the server works perfect, have to replace it.