UFS do I need to reinstall to 2nd internal disk?

from other thread:
I would advise installing sysutils/smartmontools and checking it's report, in particular:
# smartctl -a /dev/ada0 | grep Reallocated_Sector
If the last number is not zero, your disk is degraded and will fail soon. You can also run a test:

root@nofapp:~ # mount
/dev/ada0p2 on / (ufs, local, journaled soft-updates)
devfs on /dev (devfs, local, multilabel)
/dev/ada1 on /mnt/a (ufs, local, soft-updates
root@nofapp:~ # smartctl -a /dev/ada0 | grep Reallocated_Sector
5 Reallocated_Sector_Ct 0x0033 100 100 005 Pre-fail Always - 1

this is my os disk

I could also reformat and put ada0+1 in zfs stripe? would that gloss over this crap ada0 is doing? or is that disk a hunk of junk now?
If the hardware of the disk will die it will make no real difference if the system runs on ZFS or UFS. If "Reallocated_Sector" is stable 1 for some time I would not worry too much. But maintain a copy of /etc, /usr/local/etc and of course of /usr/home and other special settings just in case. dump(8) and restore(8) from a unreliable source is somehow unreliable.

Basically I guess that the crashes are not disk related. The advise of aragats has been the first to check and to be monitored. The ideas of _martin are good to follow up. I am just a hobbyist. What does not help is to open more threads related to a single topic ;). I wish you success in fixing the issue!
Modern harddrives have a bit of spare space to map bad sectors to. You will not notice this as it's done by the drive's firmware. But once this spare bit of space is full bad blocks will start showing up. There's nothing you can do about this, it simply means the disk will need to be replaced.