So I was performing a replacement and upgrade of drives. No drive had errors.
Before: 4tb parity and 6x2tb data drives
replaced the parity with 8tb wd drive no problems.
Then replaced drive 1 with another 8tb wd, this one took about 30 minutes to mount after I assigned it, then the parity sync finished without problems.
Today I replaced data drive 2 with a 8tb seagate drive, assigned it, and it stayed at mounting drives, for more than an hour, and monitoring the server with top comand didn't seem to be any activity.
I tried the comand reboot and shutdown but it didnt work. the putty session closed but it stayed on, and could login again. the web interface at this point did not respond any more.
then I tried this instructions to reboot https://wiki.unraid.net/Console#To_cleanly_Stop_the_array_from_the_command_line
and this time it took ssh out because I couldn't login anymore, but still did not shutdown, so I forced shutdown on the power button.
so now after reboot the webinterface does not load, and it seems to be stuck at mounting disk2:
I can still acess files on disk 1 and 2, in fact I needed to copy some of them with rsync and it was really slow like 2MB/s
dmesg.txt
syslog.txt