https://community.cloudera.com/t5/Archives-of-Support-Questions/is-it-safe-to-run-e2fsck-y-dev-sdXX-on-hdfs-files/m-p/194672#M71270 <P>we see the system log on one of the worker machine ( dmesg )</P><P>and from the log we saw that:</P><P>(sdc): warning: mounting fs with errors, running e2fsck is recommended</P><P>disk - sdc include the HDFS folder - hdfs files</P><PRE>df | grep sdc /dev/sdc 1922721048 1560852 1921143812 1% /grop/sdc ls /grop/sdc/hadoop/ hdfs yarn</PRE><P>so is it safe to run the following ( as OS logs recommended ) , &lt;in spite disk include HDFS files , is it risky?&gt;</P><PRE>e2fsck -y /dev/sdc <BR /></PRE> Tue, 14 Nov 2017 02:30:29 GMT mike_bronson7 2017-11-14T02:30:29Z https://community.cloudera.com/t5/Archives-of-Support-Questions/is-it-safe-to-run-e2fsck-y-dev-sdXX-on-hdfs-files/m-p/194672#M71270 <P>we see the system log on one of the worker machine ( dmesg )</P><P>and from the log we saw that:</P><P>(sdc): warning: mounting fs with errors, running e2fsck is recommended</P><P>disk - sdc include the HDFS folder - hdfs files</P><PRE>df | grep sdc /dev/sdc 1922721048 1560852 1921143812 1% /grop/sdc ls /grop/sdc/hadoop/ hdfs yarn</PRE><P>so is it safe to run the following ( as OS logs recommended ) , &lt;in spite disk include HDFS files , is it risky?&gt;</P><PRE>e2fsck -y /dev/sdc <BR /></PRE> Tue, 14 Nov 2017 02:30:29 GMT https://community.cloudera.com/t5/Archives-of-Support-Questions/is-it-safe-to-run-e2fsck-y-dev-sdXX-on-hdfs-files/m-p/194672#M71270 mike_bronson7 2017-11-14T02:30:29Z https://community.cloudera.com/t5/Archives-of-Support-Questions/is-it-safe-to-run-e2fsck-y-dev-sdXX-on-hdfs-files/m-p/194673#M71271 <P>f you don't run the filesystem checker, the apparent corruption in the filesystem may get worse. Unchecked, this can lead to data corruption or at the unlikely worst destruction of the filesystem.</P><P>During the filesystem check, file structures within the filesystem will be checked, and if necessary repaired. The repair takes no account of content; it's all about making sure the filesystem is self-consistent.</P><P>If you run <CODE>e2fsck -y /dev/sdc</CODE> you have no opportunity to validate the corrections being applied.</P><P>On the other hand if you run <CODE>e2fsck -n /dev/sdc</CODE> you can see what would happen without it actually being applied, and if you run <CODE>e2fsck /dev/sdc</CODE> you will be asked each time a significant correction needs to be applied.</P><P><STRONG>In summary</STRONG></P><UL> <LI>If you ignore the warning and do nothing, over time you may lose your data</LI><LI>If you run with <CODE>-y</CODE> you have no option to review the potentially destructive changes, and you may lose your data</LI><LI>If you run with <CODE>-n</CODE> you will not fix any errors, and over time may lose your data, but you will get to review the set of changes that would be made</LI><LI>If you run with no special flag you will be prompted to fix relevant errors, and you can decide for each whether you are going to need direct professional assistance</LI></UL><P><STRONG>Recommendation</STRONG></P><UL> <LI>Run <CODE>e2fsck -n /dev/sdc</CODE> to review the errors</LI><LI>Decide whether this merits a subsequent <CODE>e2fsck /dev/sdc</CODE> (or possibly <CODE>e2fsck -y /dev/sdc</CODE>) or whether you would prefer to obtain direct professional assistance</LI></UL> Thu, 23 Nov 2017 01:26:35 GMT https://community.cloudera.com/t5/Archives-of-Support-Questions/is-it-safe-to-run-e2fsck-y-dev-sdXX-on-hdfs-files/m-p/194673#M71271 mike_bronson7 2017-11-23T01:26:35Z