Is this a sign of dying hard drive?
Today I wasn't able to access one of my hard drives, after reboot it seems to work now, but i'm worried it's going to die soon.
/var/log/messages
Jul 4 17:05:02 host-37 kernel: [401496.020869] ata8: EH complete
Jul 4 17:05:02 host-37 kernel: [401496.021146] sd 0:0:1:0: [sdf] Unhandled error code
Jul 4 17:05:02 host-37 kernel: [401496.021148] sd 0:0:1:0: [sdf] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 4 17:05:02 host-37 kernel: [401496.021152] sd 0:0:1:0: [sdf] CDB: Read(10): 28 00 20 15 56 38 00 04 00 00
Jul 4 17:05:02 host-37 kernel: [401496.046456] sd 0:0:1:0: [sdf] Unhandled error code
Jul 4 17:05:02 host-37 kernel: [401496.046459] sd 0:0:1:0: [sdf] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 4 17:05:02 host-37 kernel: [401496.046462] sd 0:0:1:0: [sdf] CDB: Read(10): 28 00 20 15 52 38 00 04 00 00
Jul 4 17:05:02 host-37 kernel: [401496.070739] sd 0:0:1:0: [sdf] Unhandled error code
Jul 4 17:05:02 host-37 kernel: [401496.070743] sd 0:0:1:0: [sdf] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 4 17:05:02 host-37 kernel: [401496.070747] sd 0:0:1:0: [sdf] CDB: Read(10): 28 00 20 15 4e 38 00 04 00 00
Jul 4 17:05:02 host-37 kernel: [401496.094011] sd 0:0:1:0: [sdf] Unhandled error code
Jul 4 17:05:02 host-37 kernel: [401496.094015] sd 0:0:1:0: [sdf] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 4 17:05:02 host-37 kernel: [401496.094019] sd 0:0:1:0: [sdf] CDB: Read(10): 28 00 47 51 b8 80 00 04 00 00
Jul 4 17:05:02 host-37 kernel: [401496.116921] sd 0:0:1:0: [sdf] Unhandled error code
Jul 4 17:05:02 host-37 kernel: [401496.116924] sd 0:0:1:0: [sdf] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 4 17:05:02 host-37 kernel: [401496.116927] sd 0:0:1:0: [sdf] CDB: Read(10): 28 00 47 51 b4 80 00 04 00 00
Jul 4 17:05:02 host-37 kernel: [401496.139688] sd 0:0:1:0: [sdf] Unhandled error code
Jul 4 17:05:02 host-37 kernel: [401496.139692] sd 0:0:1:0: [sdf] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 4 17:05:02 host-37 kernel: [401496.139698] sd 0:0:1:0: [sdf] CDB: Read(10): 28 00 47 51 b0 80 00 04 00 00
Jul 4 17:05:02 host-37 kernel: [401496.162018] sd 0:0:1:0: [sdf] Unhandled error code
Jul 4 17:05:02 host-37 kernel: [401496.162021] sd 0:0:1:0: [sdf] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Jul 4 20:19:05 host-37 kernel: [413133.616251] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:19:35 host-37 kernel: [413163.682537] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:20:05 host-37 kernel: [413193.748847] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:20:35 host-37 kernel: [413223.815141] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:21:05 host-37 kernel: [413253.881444] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:21:35 host-37 kernel: [413283.947876] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:22:05 host-37 kernel: [413314.014181] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:22:35 host-37 kernel: [413344.080356] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:23:05 host-37 kernel: [413374.146646] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:23:35 host-37 kernel: [413404.212943] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:24:05 host-37 kernel: [413434.279249] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:24:36 host-37 kernel: [413464.345590] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:25:06 host-37 kernel: [413494.411870] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:25:36 host-37 kernel: [413524.478148] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:26:06 host-37 kernel: [413554.544429] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:26:36 host-37 kernel: [413584.610738] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:27:06 host-37 kernel: [413614.677064] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:27:36 host-37 kernel: [413644.743354] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:28:06 host-37 kernel: [413674.809659] XFS (sdf1): xfs_log_force: error 5 returned.
Jul 4 20:28:36 host-37 kernel: [413704.876061] XFS (sdf1): xfs_log_force: error 5 returned.
Yes that seems to be the case. I'd use SMART to verify (if your drive/BIOS supports it)
There are some self tests etc which you may preform. ie something like:
smartctl -a /dev/sdf
smartctl --test=short /dev/sdf
You can check the man page.
I'd make sure everything was backed up though before running any tests just in case. I'd also consider mounting the disk read-only and run a full backup if no backup is in place already.