Ideas To Save Failing System?

[Drew Tomlinson]

I have system running 4.8 that seems to be losing a hard drive.  I have many
entries such as these in /var/log/messages:

Sep 14 17:44:43 blacksheep /kernel: ad0s1a: UDMA ICRC error writing fsbn
131265 of 65600-65615 (ad0s1 bn 131265; cn 10 tn 93 sn 36) status=51
error=ff

Sep 14 17:44:43 blacksheep /kernel: ad0s1a: hard error writing fsbn 131808
of 65872-65887 (ad0s1 bn 131808; cn 10 tn 102 sn 12) status=51 error=04

I have a root session on the machine but it will not respond to any
commands.  Everything gets errors such as these:

blacksheep# shutdown -r now
/sbin/shutdown: Input/output error.

blacksheep# ps -acux
/bin/ps: Input/output error.

blacksheep# ls
Segmentation fault (core dumped)

Is there anything I can do to save this machine?  I'm afraid if I power it
off, the disk will be corrupt and it probably won't boot.  I'd really like
to make a backup and then replace the disk.  Any ideas?

Thanks,

Drew