{{tag>[linux mdadm raid raid1 failed badblocks]}}
=====Test hard drive for defects, find bad blocks=====

====smartctl====
  * Start the smartctl long test:<code># smartctl -t long /dev/sdb
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.10.0-229.11.1.el7.x86_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 Extended self-test routine immediately in off-line mode".
Drive command "Execute SMART Extended self-test routine immediately in off-line mode" successful.
Testing has begun.
Please wait 384 minutes for test to complete.
Test will complete after Mon Sep  7 14:01:01 2015

Use smartctl -X to abort test.
</code>
  * Show health (after test):<code>smartctl -H /dev/sdb
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.10.0-229.11.1.el7.x86_64] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

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




#  smartctl -l selftest /dev/sdb
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.10.0-229.11.1.el7.x86_64] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF READ SMART DATA SECTION ===
SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Extended offline    Completed without error       00%     28460         -
# 2  Short offline       Completed without error       00%     25709         -
# 3  Short offline       Completed without error       00%     25541         -
# 4  Short offline       Completed without error       00%     25218         -
# 5  Short offline       Completed without error       00%     25113         -
# 6  Short offline       Completed without error       00%     24960         -
# 7  Short offline       Completed without error       00%     24813         -
# 8  Short offline       Completed without error       00%     24656         -
# 9  Short offline       Completed without error       00%     24488         -
#10  Short offline       Completed without error       00%     24320         -
#11  Short offline       Completed without error       00%     24152         -
#12  Short offline       Completed without error       00%     23984         -


# smartctl -a /dev/sdb</code>
====badblocks====
  * Start screen, badblocks is a long running process. Using it on one of my 2TB disks took 6 days. You can speed it up with the -b and -c option.
  * Non-destructive search for bad blocks:<code># badblocks -nsv /dev/sdb
Checking for bad blocks in non-destructive read-write mode
From block 0 to 1953514583
Checking for bad blocks (non-destructive read-write test)
Testing with random pattern:   0.00% done, 0:21 elapsed. (0/0/0 errors)</code>