Checking your HDD

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Tags: howto, linux, learning

Do one thing and do it well.

Unix Philosophy

This article describes a tool for testing your HDD on a daily basis and how can you fill it completely with zeros or random numbers to check it for broken sectors.

I was spending a whole day installing and configuring 4 different operating systems on my new Desktop PC - I didn't use virtualization my Windows because I wanted to use it for gaming (especially Fallout 3). After four weeks the disasters happened: My hard disk drive (HDD)was broken. Before spending a whole installing your new systems, it is worth spending a day to check your new HDD.

Symptoms of a breaking HDD

If you encounter any of the following things you can be sure that your HDD will break soon:

  • working with Blue Screens and occasionally system fall downs
  • problems with installing new OS - even on Knoppix
  • overwriting the hard disk completely
  • blinking LED even if you are not working - is a sign that the HDD disk is writing the content into still valid sectors

Checking your new HDD with smartools

Smartmontools is an analysis tool for Linux/Unix systems which allows you to check your hard disk - even on your regular usage. The program consists of two parts: smartctl (checking and evaluating HDD parameters) and smartd (is daemon to check your HDD on a regularly state).

Install the tool with the following command:

$ sudo apt-get install smartmontools

Using smartctl for HDD diagnosing

To get an overview of your new HDD please perform:

$ sudo smartctl -A /dev/sda

The -A options says that it will only print the vendor specific informations:

$ sudo smartctl -A /dev/sda
smartctl 6.2 2013-04-20 r3812 [i686-linux-3.11.0-15-generic] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF READ SMART DATA SECTION ===
SMART Attributes Data Structure revision number: 1
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
  9 Power_On_Hours          0x0032   099   099   000    Old_age   Always       -       199
 12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       114
177 Wear_Leveling_Count     0x0013   099   099   000    Pre-fail  Always       -       9
179 Used_Rsvd_Blk_Cnt_Tot   0x0013   100   100   010    Pre-fail  Always       -       0
181 Program_Fail_Cnt_Total  0x0032   100   100   010    Old_age   Always       -       0
182 Erase_Fail_Count_Total  0x0032   100   100   010    Old_age   Always       -       0
183 Runtime_Bad_Block       0x0013   100   100   010    Pre-fail  Always       -       0
187 Uncorrectable_Error_Cnt 0x0032   100   100   000    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0032   055   055   000    Old_age   Always       -       45
195 ECC_Error_Rate          0x001a   200   200   000    Old_age   Always       -       0
199 CRC_Error_Count         0x003e   100   100   000    Old_age   Always       -       0
235 POR_Recovery_Count      0x0012   099   099   000    Old_age   Always       -       8
241 Total_LBAs_Written      0x0032   099   099   000    Old_age   Always       -       2076944882

By using the following command

$ sudo smartctl --all /dev/sda

you will get all any information about your hard disk:

$ smartctl --all /dev/sda
smartctl 6.2 2013-04-20 r3812 [i686-linux-3.11.0-15-generic] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Samsung based SSDs
Device Model:     Samsung SSD 840 PRO Series
Serial Number:    S1ATNEAD710430B
LU WWN Device Id: 5 002538 5503e9703
Firmware Version: DXM05B0Q
User Capacity:    256.060.514.304 bytes [256 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-2, ATA8-ACS T13/1699-D revision 4c
SATA Version is:  SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Sat Feb 22 08:38:14 2014 CET
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:  (0x00) Offline data collection activity
                    was never started.
                    Auto Offline Data Collection: Disabled.
Self-test execution status:      ( 244) Self-test routine in progress...
                    40% of test remaining.
Total time to complete Offline
data collection:        (53956) seconds.
Offline data collection
capabilities:            (0x53) SMART execute Offline immediate.
                    Auto Offline data collection on/off support.
                    Suspend Offline collection upon new
                    command.
                    No 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:    (   2) minutes.
Extended self-test routine
recommended polling time:    (  20) 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: 1
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
  9 Power_On_Hours          0x0032   099   099   000    Old_age   Always       -       199
 12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       114
177 Wear_Leveling_Count     0x0013   099   099   000    Pre-fail  Always       -       9
179 Used_Rsvd_Blk_Cnt_Tot   0x0013   100   100   010    Pre-fail  Always       -       0
181 Program_Fail_Cnt_Total  0x0032   100   100   010    Old_age   Always       -       0
182 Erase_Fail_Count_Total  0x0032   100   100   010    Old_age   Always       -       0
183 Runtime_Bad_Block       0x0013   100   100   010    Pre-fail  Always       -       0
187 Uncorrectable_Error_Cnt 0x0032   100   100   000    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0032   055   055   000    Old_age   Always       -       45
195 ECC_Error_Rate          0x001a   200   200   000    Old_age   Always       -       0
199 CRC_Error_Count         0x003e   100   100   000    Old_age   Always       -       0
235 POR_Recovery_Count      0x0012   099   099   000    Old_age   Always       -       8
241 Total_LBAs_Written      0x0032   099   099   000    Old_age   Always       -       2077259002

SMART Error Log Version: 1
No Errors Logged

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
  255  203828736  203894271  Read_scanning was never started
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.

Important of the output is the parameter "PASSED", it tells you that the test is over. You can perform longer tests of your hard disk with:

$ sudo smartctl -t long /dev/sda

Depending on the size of your HDD, it takes some time. For checking a whole 500 GB the program runs about 80 minutes. It is even possible to check if your HDD has damage incurred during transporting the drive with the conveyance option:

$ sudo smartctl -t conveyance /dev/sda

Performing long time diagnostic with smartd

The first step is to give the daemon the permission to run checks in the background:

$ vim /etc/default/smartmontools
> start_smartd=yes

Find the line with and uncomment it:

# uncomment to start smartd on system startup
# start_smartd=yes

The configuration file for the daemon can be found under /etc/smartd.conf. Here only one line is sufficient to check all HDDs:

DEVICESCAN -m matthias@wikimatze.de -M exec /usr/share/smartmontools/smartd-runner

Let's get through each line step-by-step:

  • DEVICESCAN: will scan all HDDs in the range between /dev/hd[a-I] .. /dev/sd[a-z], which support SMART
  • -m matthias@wikimatze.de: in case of an error, an email will be sent to this address
  • -M: the frequency of emails departure
    • -M exec: don't send testmails
    • -M test: send a testmail (when using this option, you must leave out the /usr/share/smartmontools/smartd-runner)
    • -M daily: send daily reports Now it's time to test our configuration: bash $ smartd -q onecheck

You can check your internal mails with $ sudo mail (you need install Postfix on your OS) and rebooting the daemon:

/etc/init.d/smartmontools restart

If you want to have a graphical client for this tool, you need to run:

$ sudo apt-get install gsmartcontrol

You need then to start the program in sudo mode to detect all HDDs sudo gsmartcontrol.

Checking the whole space on your HDD

You know these tiny small dd commands? No, it's time to learn and understand them. They are very handy to fill your your whole HDD with lovely zeros and ones.

dd stands for data definition. It has direct access on the hard disk and can read boot sectors - it is even used to create iso files of CDs.

Writing zeros or random numbers

$ dd if=/dev/zero of=/dev/sda

Take from the input file (if) the zeros (/dev/zero) and write them on the output file (of) /dev/sda. If the command has written the whole hard disk, it will end.

Speeding up the process with faster writing

Normally, each block of the hard disk has the size of 512 KB. To set the blocksize on 1 MB (1024 KB), we can speed up the writing speed with the factor two. We can achieve do this with the bs option.

$ dd if=/dev/zero of=/dev/sda bs=1024

Jump over errors

dd will end, if it detects a broken sector. With the conv=noerror option, dd will write till the HDD is full even over broken sectors:

$ dd if=/dev/zero conv=noerror of=/dev/sda bs=1024

Other useful parameters are notrunc (write the output file completely) or sync (write with the full length).

Running the dd command with status display

We can use the pv command to monitor the progress of data through a pipe. First we need to install it:

$ sudo apt-get install pv

To get an overview about how many MB or GB have already be written, use the following command:

$ dd if=/dev/random conv=notrunc,sync bs=1024 | pv > /dev/sda

Conclusion

A broken HDD is a bad thing, but if you know the symptoms it saves you a lot of time because you you know that you have to buy new hardware. Always have backup on an external HDD to have a save data replacement.

It is good to run a couple of tests before you start implementing your whole system.

Further reading

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