Smartmontools – How does a failure look?
There are some things that you would rather not find out for yourself. That does not mean, however, that they are not useful to see at all. One of those things that I had wondered about was how harddisk SMART failures/errors are shown. For those who are familiar with Smartmontools know that smartctl can produce quite some information when started as:
smartctl –all /dev/sda
However, there’s this handy switch ‘-H‘ (i.e. “smartctl -H /dev/sda“) which supposedly shows you its health status. Now when everything is fine, the disk’s health is reported as ‘PASSED‘. This is nice, but the PASSED case isn’t particularly interesting. What does it look like, when it is not ‘PASSing’? Well, then it looks like this:
smartctl 5.41 2011-06-09 r3365 [x86_64-linux-3.2.0-4-amd64] (local build)
Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net
=== 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.
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
5 Reallocated_Sector_Ct 0x0033 129 129 140 Pre-fail Always FAILING_NOW 561
Now, I have to say that this wasn’t anything unexpected. After all, the PC was suffering from continuous read errors yesterday. But, it is good to know that there is something serious going on, instead of some random unexplained anomaly, which is definitely confirmed by above message and failure details. It does not mean that the details are perfectly accurate, however if you love your data, it’s better to err on the side of caution. Especially given subtle hints like these.