dmesg

[ 1747.072687] blk_update_request: I/O error, dev sdb, sector 0
[ 1747.079277] sd 0:0:0:0: [sdb] tag#1 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 1747.088131] sd 0:0:0:0: [sdb] tag#1 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 1747.095511] blk_update_request: I/O error, dev sdb, sector 0
[ 1747.101245] Buffer I/O error on dev sdb, logical block 0, async page read
[ 1782.866625] ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
[ 1782.873756] ata2.00: failed command: IDENTIFY DEVICE
[ 1782.879119] ata2.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 1 pio 512 in
         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[ 1782.893805] ata2.00: status: { DRDY }
[ 1782.897834] ata2: hard resetting link
[ 1788.446486] ata2: link is slow to respond, please be patient (ready=0)
[ 1792.946484] ata2: SRST failed (errno=-16)
[ 1792.950547] ata2: hard resetting link
[ 1798.496484] ata2: link is slow to respond, please be patient (ready=0)
[ 1802.996484] ata2: SRST failed (errno=-16)
[ 1803.000560] ata2: hard resetting link
[ 1808.546484] ata2: link is slow to respond, please be patient (ready=0)
[ 1838.006484] ata2: SRST failed (errno=-16)
[ 1838.010547] ata2: limiting SATA link speed to 1.5 Gbps
[ 1838.015734] ata2: hard resetting link
[ 1843.026484] ata2: SRST failed (errno=-16)
[ 1843.030545] ata2: reset failed, giving up
[ 1843.034588] ata2.00: disabled
[ 1843.038105] ata2: EH complete

smart

root@debian:~# smartctl -a /dev/sdc
smartctl 6.4 2014-10-07 r4002 [armv5tel-linux-4.4.0-kirkwood-tld-1] (local build)
Copyright (C) 2002-14, Bruce Allen, Christian Franke, www.smartmontools.org

Standard Inquiry (36 bytes) failed [Input/output error]
Retrying with a 64 byte Standard Inquiry
Standard Inquiry (64 bytes) failed [Input/output error]
A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.