Your disks are having problems:
Dec 13 01:13:14 Juno kernel: sd 8:0:1:0: [sdw] tag#6846 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:13:14 Juno kernel: sd 8:0:1:0: [sdw] tag#6846 CDB: opcode=0x88 88 00 00 00 00 05 74 ff ff 80 00 00 00 08 00 00
Dec 13 01:13:14 Juno kernel: print_req_error: I/O error, dev sdw, sector 23437770624
Dec 13 01:13:14 Juno rc.diskinfo[9245]: SIGHUP received, forcing refresh of disks info.
Dec 13 01:13:14 Juno kernel: sd 7:0:10:0: [sdp] tag#1601 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:13:14 Juno kernel: sd 7:0:10:0: [sdp] tag#1601 CDB: opcode=0x88 88 00 00 00 00 04 8c 3f ff 80 00 00 00 08 00 00
Dec 13 01:13:14 Juno kernel: print_req_error: I/O error, dev sdp, sector 19532873600
Dec 13 01:13:15 Juno kernel: sd 9:0:0:0: [sdx] tag#472 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:13:15 Juno kernel: sd 9:0:0:0: [sdx] tag#472 CDB: opcode=0x88 88 00 00 00 00 02 ba a0 f4 00 00 00 00 08 00 00
Dec 13 01:13:15 Juno kernel: print_req_error: I/O error, dev sdx, sector 11721044992
Dec 13 01:13:25 Juno kernel: sd 7:0:11:0: [sdq] tag#1609 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:13:25 Juno kernel: sd 7:0:11:0: [sdq] tag#1609 CDB: opcode=0x88 88 00 00 00 00 04 8c 3f ff 80 00 00 00 08 00 00
Dec 13 01:13:25 Juno kernel: print_req_error: I/O error, dev sdq, sector 19532873600
Dec 13 01:13:25 Juno rc.diskinfo[9245]: SIGHUP received, forcing refresh of disks info.
Dec 13 01:13:25 Juno kernel: sd 9:0:2:0: [sdz] tag#3693 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:13:25 Juno kernel: sd 9:0:2:0: [sdz] tag#3693 CDB: opcode=0x88 88 00 00 00 00 04 8c 3f ff 80 00 00 00 08 00 00
Dec 13 01:13:25 Juno kernel: print_req_error: I/O error, dev sdz, sector 19532873600
Dec 13 01:13:35 Juno kernel: sd 9:0:6:0: [sdad] tag#5479 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:13:35 Juno kernel: sd 9:0:6:0: [sdad] tag#5479 CDB: opcode=0x88 88 00 00 00 00 04 8c 3f ff 80 00 00 00 08 00 00
Dec 13 01:13:35 Juno kernel: print_req_error: I/O error, dev sdad, sector 19532873600
Dec 13 01:13:35 Juno unassigned.devices: Error: shell_exec(/usr/sbin/hdparm -C /dev/sdaa 2>/dev/null | /bin/grep -c standby) took longer than 10s!
Dec 13 01:13:56 Juno kernel: sd 9:0:1:0: [sdy] tag#1686 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:13:56 Juno kernel: sd 9:0:1:0: [sdy] tag#1686 CDB: opcode=0x88 88 00 00 00 00 05 74 ff ff 80 00 00 00 08 00 00
Dec 13 01:13:56 Juno kernel: print_req_error: I/O error, dev sdy, sector 23437770624
Dec 13 01:13:56 Juno kernel: sd 9:0:7:0: [sdae] tag#1060 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:13:56 Juno kernel: sd 9:0:7:0: [sdae] tag#1060 CDB: opcode=0x88 88 00 00 00 00 04 8c 3f ff 80 00 00 00 08 00 00
Dec 13 01:13:56 Juno kernel: print_req_error: I/O error, dev sdae, sector 19532873600
Dec 13 01:13:56 Juno unassigned.devices: Error: shell_exec(/usr/sbin/hdparm -C /dev/sdae 2>/dev/null | /bin/grep -c standby) took longer than 10s!
Dec 13 01:13:56 Juno unassigned.devices: Error: shell_exec(/usr/sbin/hdparm -C /dev/sdaa 2>/dev/null | /bin/grep -c standby) took longer than 10s!
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Dec 13 01:14:24 Juno kernel: sd 9:0:4:0: [sdab] tag#1694 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:14:24 Juno kernel: sd 9:0:4:0: [sdab] tag#1694 CDB: opcode=0x88 88 00 00 00 00 04 8c 3f ff 80 00 00 00 08 00 00
Dec 13 01:14:24 Juno kernel: print_req_error: I/O error, dev sdab, sector 19532873600
Dec 13 01:14:24 Juno kernel: sd 9:0:5:0: [sdac] tag#4039 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:14:24 Juno kernel: sd 9:0:5:0: [sdac] tag#4039 CDB: opcode=0x88 88 00 00 00 00 04 8c 3f ff 80 00 00 00 08 00 00
Dec 13 01:14:24 Juno kernel: print_req_error: I/O error, dev sdac, sector 19532873600
Dec 13 01:14:24 Juno unassigned.devices: Error: shell_exec(/usr/sbin/hdparm -C /dev/sdab 2>/dev/null | /bin/grep -c standby) took longer than 10s!
Dec 13 01:14:36 Juno kernel: sd 9:0:3:0: [sdaa] tag#1695 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x00
Dec 13 01:14:36 Juno kernel: sd 9:0:3:0: [sdaa] tag#1695 CDB: opcode=0x88 88 00 00 00 00 04 8c 3f ff 80 00 00 00 08 00 00
Dec 13 01:14:36 Juno kernel: print_req_error: I/O error, dev sdaa, sector 19532873600
Dec 13 01:14:36 Juno unassigned.devices: Error: shell_exec(/usr/sbin/hdparm -C /dev/sdae 2>/dev/null | /bin/grep -c standby) took longer than 10s!
I would also remove the preclear plugin until you get this sorted out. The rc.diskinfo is a preclear background task that is also doing disk io.
Edit: You also have an array disk with read errors:
Dec 26 04:40:03 Juno root: Fix Common Problems: Error: disk9 (WDC_WD60EFRX-68MYMN1_WD-WX11DB4H8SXT) has read errors
You need to get these issues fixed before you start losing data.