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smartctl notes

Thu, 07/15/2010 - 10:25 — sandip

Below is a list of smartctl commands I frequently use to quickly verify disk health and status, specially when you have smartd logging errors to messages log file.

  • Print all SMART (Self-Monitoring, Analysis and Reporting Technology) information for drive /dev/sda (Primary Master).

    smartctl -a /dev/sda

  • Enable SMART on device.

    smartctl --smart=on /dev/sda

  • Get info about the device:

    smartctl -i /dev/sda

  • Show the capabilities of drive. Also provides status when tests are being carried out.

    smartctl -c /dev/sda

  • Basic health status:

    smartctl -H /dev/sda

  • Display attributes. The attributes to look out for failing disk is Reallocated_Sector_Ct, Reallocated_Event_Count, Current_Pending_Sector and Offline_Uncorrectable. Their RAW_VALUE should normally be "0".

    smartctl -A /dev/sda

  • Immediate offline test which updates attributes value. Good to run after a badblocks fsck check before checking on the attributes values.

    smartctl -t offline /dev/sda

  • Run a thorough long test if you see suspect attributes with -A option as mentioned above.

    smartctl -t long /dev/sda

  • Examine self-test log. Shows if tests failed or passed.

    smartctl -l selftest /dev/sda

  • Display most recent error log.

    smartctl -l error /dev/sda

There are more examples in man smartctl.

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Tue, 01/18/2011 - 12:22 — Anonymous Resolving sector errors on raid partition

On software raid partitions, CurrentPendingSector or OfflineUncorrectableSector errors as logged in syslog could be corrected just failing/removing the drive and re-attaching it back so the drive is rebuilt and the problem sectors get over-written.

Below, I have 4 CurrentPending and OfflineUncorrectable sectors:

# smartctl -A /dev/sdb | grep "Current_Pending_Sector\|Offline_Uncorrectable" />197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always       -     ;  4
198 Offline_Uncorrectable   0x0010   100   100   000    Old_age   Offline    ;  -     ;  4

Doing a selftest, confirms that the first sector lies in the second partition:

# smartctl -l selftest /dev/sdb
smartctl version 5.38 [x86_64-redhat-linux-gnu] Copyright (C) 2002-8 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

=== 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: read failure    ;   90%     18654         3166126

Sector 3166126 lies in the second partition:

# fdisk -lu /dev/sdb

Disk /dev/sdb: 750.1 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders, total 1465149168 sectors
Units = sectors of 1 * 512 = 512 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *     ;     63      401624      200781   fd  Linux raid autodetect
/dev/sdb2          401625  1465144064   732371220   fd  Linux raid autodetect

Locate the raid partition:

# grep sdb2 /proc/mdstat
md1 : active raid10 sdb2[4] sdd2[3] sdc2[2] sda2[0]

Make the partition faulty and remove:

# mdadm --manage /dev/md1 -f /dev/sdb2
# mdadm --manage /dev/md1 -r /dev/sdb2

Re-attach the partition and let it rebuild:

# mdadm --manage /dev/md1 -a /dev/sdb2

Once rebuilt redo selftest and check on errors:

# smartctl -t long /dev/sdb
# smartctl -A /dev/sdb | grep "Current_Pending_Sector\|Offline_Uncorrectable" /># smartctl -l selftest /dev/sdb

Drive keeps extra space available to "remap" bad sectors. This happens automatically. If uncorrectable sector errors does not resolve or comes back time and again, it means re-mappable sectors are used up and drive will probably fail soon, so best to just replace the drive.

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