What a hdd hard drive and mdadm RAID array failure looks like in Linux

[3805108.257042] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB)
[3805108.257052] sd 0:0:0:0: [sda] Write Protect is off
[3805108.257054] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[3805108.257066] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[3805108.257083] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB)
[3805108.257090] sd 0:0:0:0: [sda] Write Protect is off
[3805108.257092] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[3805108.257102] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[3805157.877358] ata1: exception Emask 0x10 SAct 0x0 SErr 0x90202 action 0xe frozen
[3805157.877360] ata1: irq_stat 0x00400000, PHY RDY changed
[3805157.877363] ata1: SError: { RecovComm Persist PHYRdyChg 10B8B }
[3805157.877366] ata1: hard resetting link
[3805158.620050] ata1: SATA link down (SStatus 0 SControl 300)
[3805158.851429] ata1: hard resetting link
[3805162.862545] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[3805162.878238] ata1.00: configured for UDMA/133
[3805162.878252] ata1: limiting SATA link speed to 1.5 Gbps
[3805162.878255] ata1: exception Emask 0x10 SAct 0x0 SErr 0x0 action 0xf t4
[3805162.878257] ata1: irq_stat 0x00400040, connection status changed
[3805162.878260] ata1: hard resetting link
[3805163.802544] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[3805163.818012] ata1.00: configured for UDMA/133
[3805163.818016] ata1: EH complete
[3805163.818088] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB)
[3805163.818098] sd 0:0:0:0: [sda] Write Protect is off
[3805163.818100] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[3805163.818112] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[3805163.818129] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB)
[3805163.818135] sd 0:0:0:0: [sda] Write Protect is off
[3805163.818137] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[3805163.818147] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[3805199.602103] ata1: exception Emask 0x10 SAct 0x0 SErr 0x90200 action 0xe frozen
[3805199.602106] ata1: irq_stat 0x00400000, PHY RDY changed
[3805199.602108] ata1: SError: { Persist PHYRdyChg 10B8B }
[3805199.602112] ata1: hard resetting link
[3805200.352548] ata1: SATA link down (SStatus 0 SControl 310)
[3805200.595987] ata1: hard resetting link
[3805203.342553] ata1: SATA link down (SStatus 0 SControl 310)
[3805204.390198] ata1: hard resetting link
[3805208.272545] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[3805208.275964] ata1.00: configured for UDMA/133
[3805208.275977] ata1: exception Emask 0x10 SAct 0x0 SErr 0x0 action 0x9 t4
[3805208.275979] ata1: irq_stat 0x00000040, connection status changed
[3805208.278116] ata1.00: configured for UDMA/133
[3805208.278120] ata1: EH complete
[3805208.278191] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB)
[3805208.278201] sd 0:0:0:0: [sda] Write Protect is off
[3805208.278203] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[3805208.278214] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[3805208.278241] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB)
[3805208.278257] sd 0:0:0:0: [sda] Write Protect is off
[3805208.278258] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[3805208.278269] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[3805211.016992] ata1: exception Emask 0x10 SAct 0x0 SErr 0x90200 action 0xe frozen
[3805211.016994] ata1: irq_stat 0x00400000, PHY RDY changed
[3805211.016996] ata1: SError: { Persist PHYRdyChg 10B8B }
[3805211.017000] ata1: hard resetting link
[3805211.760051] ata1: SATA link down (SStatus 0 SControl 310)
[3805216.762533] ata1: hard resetting link
[3805217.112548] ata1: SATA link down (SStatus 0 SControl 310)
[3805222.112533] ata1: hard resetting link
[3805222.462549] ata1: SATA link down (SStatus 0 SControl 310)
[3805222.462555] ata1.00: disabled
[3805222.462568] ata1: EH complete
[3805222.462574] sd 0:0:0:0: rejecting I/O to offline device
[3805222.462585] ata1.00: detaching (SCSI 0:0:0:0)
[3805222.462592] end_request: I/O error, dev sda, sector 1887460551
[3805222.462596] md: super_written gets error=-5, uptodate=0
[3805222.462599] raid1: Disk failure on sda1, disabling device.
[3805222.462600] raid1: Operation continuing on 1 devices.
[3805222.462868] sd 0:0:0:0: [sda] Synchronizing SCSI cache
[3805222.462964] sd 0:0:0:0: [sda] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK,SUGGEST_OK
[3805222.462967] sd 0:0:0:0: [sda] Stopping disk
[3805222.462972] sd 0:0:0:0: [sda] START_STOP FAILED
[3805222.462973] sd 0:0:0:0: [sda] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK,SUGGEST_OK
[3805227.022869] RAID1 conf printout:
[3805227.022871] --- wd:1 rd:2
[3805227.022874] disk 0, wo:0, o:1, dev:sdc1
[3805227.022875] disk 1, wo:1, o:0, dev:sda1
[3805227.024931] RAID1 conf printout:
[3805227.024935] --- wd:1 rd:2
[3805227.024938] disk 0, wo:0, o:1, dev:sdc1
cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md_d20 : active raid1 sde1[0]
      1953511936 blocks [2/1] [U_]
      bitmap: 231/233 pages [924KB], 4096KB chunk

md_d1 : active raid1 sda2[1] sdc2[0]
      20490816 blocks [2/2] [UU]

md12 : active raid1 sdb1[0] sdd1[1]
      1953511936 blocks [2/2] [UU]
      bitmap: 0/233 pages [0KB], 4096KB chunk

md0 : active raid1 sda1[2](F) sdc1[0]
      943730240 blocks [2/1] [U_]
      bitmap: 67/226 pages [268KB], 2048KB chunk