Smartctl

The disk of any server is very important as it stores critical information, this would include the OS information and any additional files which you may of added over time. You can check the status of the disk with the following commands:

smartctl short test -- 1 Minute

smartctl --test=short /dev/sda

smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.10.23-xxxx-std-ipv6-64] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF OFFLINE IMMEDIATE AND SELF-TEST SECTION ===
Sending command: "Execute SMART Short self-test routine immediately in off-line mode".
Drive command "Execute SMART Short self-test routine immediately in off-line mode" successful.
Testing has begun.
Please wait 1 minutes for test to complete.
Test will complete after Tue Feb 10 20:30:12 2015

Use smartctl -X to abort test.
fdisk -l -- This will list all current disk.

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x0006dd70

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        4096  1952473087   976234496   83  Linux
/dev/sda2      1952473088  1953519615      523264   82  Linux swap / Solaris
sudo smartctl -a -d ata /dev/sda -- This will provide you with the disk health and show any errors.

smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.13.0-45-generic] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Toshiba 3.5" HDD DT01ACA...
Device Model:     TOSHIBA DT01ACA100
Serial Number:    13FHX2MPS
LU WWN Device Id: 5 000039 ff2e36a00
Firmware Version: MS2OA750
User Capacity:    1,000,204,886,016 bytes [1.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    7200 rpm
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ATA8-ACS T13/1699-D revision 4
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 3.0 Gb/s)
Local Time is:    Sun Feb  8 23:41:30 2015 GMT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status:  (0x84)	Offline data collection activity
					was suspended by an interrupting command from host.
					Auto Offline Data Collection: Enabled.
Self-test execution status:      (   0)	The previous self-test routine completed
					without error or no self-test has ever 
					been run.
Total time to complete Offline 
data collection: 		( 7944) seconds.
Offline data collection
capabilities: 			 (0x5b) SMART execute Offline immediate.
					Auto Offline data collection on/off support.
					Suspend Offline collection upon new
					command.
					Offline surface scan supported.
					Self-test supported.
					No Conveyance Self-test supported.
					Selective Self-test supported.
SMART capabilities:            (0x0003)	Saves SMART data before entering
					power-saving mode.
					Supports SMART auto save timer.
Error logging capability:        (0x01)	Error logging supported.
					General Purpose Logging supported.
Short self-test routine 
recommended polling time: 	 (   1) minutes.
Extended self-test routine
recommended polling time: 	 ( 133) minutes.
SCT capabilities: 	       (0x003d)	SCT Status supported.
					SCT Error Recovery Control supported.
					SCT Feature Control supported.
					SCT Data Table supported.

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000b   100   100   016    Pre-fail  Always       -       0
  2 Throughput_Performance  0x0005   139   139   054    Pre-fail  Offline      -       79
  3 Spin_Up_Time            0x0007   127   127   024    Pre-fail  Always       -       182 (Average 180)
  4 Start_Stop_Count        0x0012   100   100   000    Old_age   Always       -       55
  5 Reallocated_Sector_Ct   0x0033   100   100   005    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000b   100   100   067    Pre-fail  Always       -       0
  8 Seek_Time_Performance   0x0005   118   118   020    Pre-fail  Offline      -       33
  9 Power_On_Hours          0x0012   099   099   000    Old_age   Always       -       11315
 10 Spin_Retry_Count        0x0013   100   100   060    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       52
192 Power-Off_Retract_Count 0x0032   100   100   000    Old_age   Always       -       96
193 Load_Cycle_Count        0x0012   100   100   000    Old_age   Always       -       96
194 Temperature_Celsius     0x0002   222   222   000    Old_age   Always       -       27 (Min/Max 14/42)
196 Reallocated_Event_Count 0x0032   100   100   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0022   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0008   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x000a   200   200   000    Old_age   Always       -       0

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Completed without error       00%     11146         -
# 2  Short offline       Completed without error       00%     10751         -
# 3  Short offline       Completed without error       00%      9129         -
# 4  Short offline       Completed without error       00%      7569         -
# 5  Short offline       Completed without error       00%      6792         -
# 6  Short offline       Completed without error       00%      6788         -
# 7  Short offline       Completed without error       00%      5089         -
# 8  Short offline       Completed without error       00%      5085         -
# 9  Short offline       Completed without error       00%      2501         -
#10  Short offline       Completed without error       00%      2496         -
#11  Short offline       Completed without error       00%      2496         -
#12  Short offline       Completed without error       00%      2472         -
#13  Short offline       Completed without error       00%         5         -
#14  Short offline       Completed without error       00%         0         -
#15  Short offline       Completed without error       00%         0         -

SMART Selective self-test log data structure revision number 1
 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay. 
cat /proc/mdstat -- Shows the RAID status on the server.

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
unused devices: <none>

Hard drives will fail.
It’s a question of when it will fail rather than if it will fail.

Here is an an hard drive which has failed after 7 hours of usage, a backup is always recommended.

smartctl 5.41 2011-06-09 r3365 [x86_64-linux-2.6.32-34-pve] (local build)
Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF INFORMATION SECTION ===
Device Model:     HGST HUS724020ALA640
Serial Number:    PN2134P6KWRLWX
LU WWN Device Id: 5 000cca 22df6e167
Firmware Version: MF6OAA70
User Capacity:    2,000,398,934,016 bytes [2.00 TB]
Sector Size:      512 bytes logical/physical
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   8
ATA Standard is:  ATA-8-ACS revision 4
Local Time is:    Tue Feb 10 23:41:42 2015 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status:  (0x80)	Offline data collection activity
					was never started.
					Auto Offline Data Collection: Enabled.
Self-test execution status:      (   0)	The previous self-test routine completed
					without error or no self-test has ever 
					been run.
Total time to complete Offline 
data collection: 		(   24) seconds.
Offline data collection
capabilities: 			 (0x5b) SMART execute Offline immediate.
					Auto Offline data collection on/off support.
					Suspend Offline collection upon new
					command.
					Offline surface scan supported.
					Self-test supported.
					No Conveyance Self-test supported.
					Selective Self-test supported.
SMART capabilities:            (0x0003)	Saves SMART data before entering
					power-saving mode.
					Supports SMART auto save timer.
Error logging capability:        (0x01)	Error logging supported.
					General Purpose Logging supported.
Short self-test routine 
recommended polling time: 	 (   1) minutes.
Extended self-test routine
recommended polling time: 	 ( 255) minutes.
SCT capabilities: 	       (0x003d)	SCT Status supported.
					SCT Error Recovery Control supported.
					SCT Feature Control supported.
					SCT Data Table supported.

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000b   100   100   016    Pre-fail  Always       -       0
  2 Throughput_Performance  0x0005   100   100   054    Pre-fail  Offline      -       0
  3 Spin_Up_Time            0x0007   100   100   024    Pre-fail  Always       -       0
  4 Start_Stop_Count        0x0012   100   100   000    Old_age   Always       -       3
  5 Reallocated_Sector_Ct   0x0033   100   100   005    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000b   100   100   067    Pre-fail  Always       -       0
  8 Seek_Time_Performance   0x0005   100   100   020    Pre-fail  Offline      -       0
  9 Power_On_Hours          0x0012   100   100   000    Old_age   Always       -       7
 10 Spin_Retry_Count        0x0013   100   100   060    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       3
192 Power-Off_Retract_Count 0x0032   100   100   000    Old_age   Always       -       3
193 Load_Cycle_Count        0x0012   100   100   000    Old_age   Always       -       3
194 Temperature_Celsius     0x0002   157   157   000    Old_age   Always       -       38 (Min/Max 24/39)
196 Reallocated_Event_Count 0x0032   100   100   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0022   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0008   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x000a   196   196   000    Old_age   Always       -       16

SMART Error Log Version: 1
ATA Error Count: 16 (device log contains only the most recent five errors)
	CR = Command Register [HEX]
	FR = Features Register [HEX]
	SC = Sector Count Register [HEX]
	SN = Sector Number Register [HEX]
	CL = Cylinder Low Register [HEX]
	CH = Cylinder High Register [HEX]
	DH = Device/Head Register [HEX]
	DC = Device Command Register [HEX]
	ER = Error register [HEX]
	ST = Status register [HEX]
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.

Error 16 occurred at disk power-on lifetime: 7 hours (0 days + 7 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 51 01 07 10 00 00  Error: ICRC, ABRT at LBA = 0x00001007 = 4103

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  61 10 60 08 10 d4 40 00      07:13:27.766  WRITE FPDMA QUEUED
  61 08 58 00 d0 d4 40 00      07:13:27.766  WRITE FPDMA QUEUED
  61 08 50 78 10 d8 40 00      07:13:27.766  WRITE FPDMA QUEUED
  61 08 48 00 10 00 40 00      07:13:27.766  WRITE FPDMA QUEUED
  ec 00 00 00 00 00 a0 00      07:13:27.765  IDENTIFY DEVICE

Error 15 occurred at disk power-on lifetime: 7 hours (0 days + 7 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 51 01 17 10 d4 00  Error: ICRC, ABRT at LBA = 0x00d41017 = 13897751

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  61 08 40 20 18 d8 40 00      07:13:27.446  WRITE FPDMA QUEUED
  61 08 38 00 10 00 40 00      07:13:27.446  WRITE FPDMA QUEUED
  61 08 30 78 10 d8 40 00      07:13:27.446  WRITE FPDMA QUEUED
  61 08 28 00 d0 d4 40 00      07:13:27.446  WRITE FPDMA QUEUED
  61 10 20 08 10 d4 40 00      07:13:27.446  WRITE FPDMA QUEUED

Error 14 occurred at disk power-on lifetime: 7 hours (0 days + 7 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 51 01 27 18 d8 01  Error: ICRC, ABRT at LBA = 0x01d81827 = 30939175

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  61 08 38 78 32 dd 40 00      07:13:26.308  WRITE FPDMA QUEUED
  61 08 30 58 41 dd 40 00      07:13:26.308  WRITE FPDMA QUEUED
  61 08 28 80 32 dd 40 00      07:13:26.308  WRITE FPDMA QUEUED
  61 08 20 08 42 dd 40 00      07:13:26.308  WRITE FPDMA QUEUED
  61 08 18 70 41 dd 40 00      07:13:26.308  WRITE FPDMA QUEUED

Error 13 occurred at disk power-on lifetime: 7 hours (0 days + 7 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 51 01 27 18 d8 01  Error: ICRC, ABRT at LBA = 0x01d81827 = 30939175

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  61 08 00 78 41 dd 40 00      07:13:25.926  WRITE FPDMA QUEUED
  61 08 f0 20 18 d8 40 00      07:13:25.926  WRITE FPDMA QUEUED
  ec 00 00 00 00 00 a0 00      07:13:25.925  IDENTIFY DEVICE
  ef 03 42 00 00 00 a0 00      07:13:25.925  SET FEATURES [Set transfer mode]
  ec 00 00 00 00 00 a0 00      07:13:25.924  IDENTIFY DEVICE

Error 12 occurred at disk power-on lifetime: 7 hours (0 days + 7 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 51 01 67 41 dd 01  Error: ICRC, ABRT at LBA = 0x01dd4167 = 31277415

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  61 08 58 00 42 dd 40 00      07:13:20.268  WRITE FPDMA QUEUED
  61 08 50 68 41 dd 40 00      07:13:20.268  WRITE FPDMA QUEUED
  61 08 48 88 32 dd 40 00      07:13:20.268  WRITE FPDMA QUEUED
  61 08 40 60 41 dd 40 00      07:13:20.268  WRITE FPDMA QUEUED
  ec 00 00 00 00 00 a0 00      07:13:20.266  IDENTIFY DEVICE

SMART Self-test log structure revision number 1
No self-tests have been logged.  [To run self-tests, use: smartctl -t]


SMART Selective self-test log data structure revision number 1
 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.

SSD drives are also subject to fail as well:

smartctl 6.6 2016-05-31 r4324 [x86_64-linux-3.14.77-mod-std-ipv6-64-rescue] (local build)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Crucial/Micron MX100/MX200/M5x0/M600 Client SSDs
Device Model:     Micron_M600_MTFDDAK256MBF
Serial Number:    154110C4F492
LU WWN Device Id: 5 00a075 110c4f492
Firmware Version: MU03
User Capacity:    256,060,514,304 bytes [256 GB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    Solid State Device
Form Factor:      2.5 inches
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-3 T13/2161-D revision 4
SATA Version is:  SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Fri Jun 30 15:50:59 2017 CEST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: FAILED!
Drive failure expected in less than 24 hours. SAVE ALL DATA.
No failed Attributes found.

General SMART Values:
Offline data collection status:  (0x80)	Offline data collection activity
					was never started.
					Auto Offline Data Collection: Enabled.
Self-test execution status:      (   0)	The previous self-test routine completed
					without error or no self-test has ever 
					been run.
Total time to complete Offline 
data collection: 		(  814) seconds.
Offline data collection
capabilities: 			 (0x7b) SMART execute Offline immediate.
					Auto Offline data collection on/off support.
					Suspend Offline collection upon new
					command.
					Offline surface scan supported.
					Self-test supported.
					Conveyance Self-test supported.
					Selective Self-test supported.
SMART capabilities:            (0x0003)	Saves SMART data before entering
					power-saving mode.
					Supports SMART auto save timer.
Error logging capability:        (0x01)	Error logging supported.
					General Purpose Logging supported.
Short self-test routine 
recommended polling time: 	 (   2) minutes.
Extended self-test routine
recommended polling time: 	 (   5) minutes.
Conveyance self-test routine
recommended polling time: 	 (   3) minutes.
SCT capabilities: 	       (0x0035)	SCT Status supported.
					SCT Feature Control supported.
					SCT Data Table supported.

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x002f   100   100   000    Pre-fail  Always       -       0
  5 Reallocate_NAND_Blk_Cnt 0x0032   100   100   010    Old_age   Always       -       0
  9 Power_On_Hours          0x0032   100   100   000    Old_age   Always       -       12499
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       13
171 Program_Fail_Count      0x0032   100   100   000    Old_age   Always       -       0
172 Erase_Fail_Count        0x0032   100   100   000    Old_age   Always       -       0
173 Ave_Block-Erase_Count   0x0032   001   001   000    Old_age   Always       -       3436
174 Unexpect_Power_Loss_Ct  0x0032   100   100   000    Old_age   Always       -       12
180 Unused_Reserve_NAND_Blk 0x0033   000   000   000    Pre-fail  Always       -       1924
183 SATA_Interfac_Downshift 0x0032   100   100   000    Old_age   Always       -       0
184 Error_Correction_Count  0x0032   100   100   000    Old_age   Always       -       0
187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0
194 Temperature_Celsius     0x0022   064   053   000    Old_age   Always       -       36 (Min/Max 18/47)
196 Reallocated_Event_Count 0x0032   100   100   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0030   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x0032   100   100   000    Old_age   Always       -       0
202 Percent_Lifetime_Used   0x0030   000   000   001    Old_age   Offline  FAILING_NOW 100
206 Write_Error_Rate        0x000e   100   100   000    Old_age   Always       -       0
210 Success_RAIN_Recov_Cnt  0x0032   100   100   000    Old_age   Always       -       0
246 Total_Host_Sector_Write 0x0032   100   100   000    Old_age   Always       -       515686330412
247 Host_Program_Page_Count 0x0032   100   100   000    Old_age   Always       -       16160251554
248 Bckgnd_Program_Page_Cnt 0x0032   100   100   000    Old_age   Always       -       13516879563

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Vendor (0xff)       Completed without error       00%       200         -
# 2  Vendor (0xff)       Completed without error       00%       159         -
# 3  Vendor (0xff)       Completed without error       00%       117         -
# 4  Vendor (0xff)       Completed without error       00%        76         -
# 5  Short offline       Completed without error       00%        34         -
# 6  Short offline       Completed without error       00%        32         -
# 7  Short offline       Completed without error       00%        32         -
# 8  Vendor (0xff)       Completed without error       00%        29         -
# 9  Vendor (0xff)       Completed without error       00%        16         -
#10  Short offline       Completed without error       00%         0         -
#11  Short offline       Completed without error       00%         0         -

SMART Selective self-test log data structure revision number 1
 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.