File system can become inconsistent due to several reasons and the most common is abnormal shutdown due to hardware failure, power failure or switching off the system without proper shutdown.

Due to these reasons the superblock in a file system is not updated and has mismatched information relating to system data blocks, free blocks and inodes.

If file system is found to have problem at the booting time non interactive fsck is run and all errors which are considered safe to correct are corrected. But if still file system has problems the system boots in single user mode asking for user to manually run the fsck to correct the problems in file system. If it is run in a busy system where the file system is changing constantly fsck may see the changes as inconsistencies and may corrupt the file system.

While fsck is running it displays warning or error messages in describing the warning, error or description.

Some of the commonly used abbreviation are given below. BLK — Block number DUP — Duplicate block number DIR — Directory name CG — Cylinder group MTIME — Time file was last modified UNREF — Unreferenced.

If the superblock is corrupted the file system still can be repaired using alternate superblock which are formed while making new file system. During fsck the number of free blocks listed in a superblock and actual unallocated free blocks count does not match. This error can be corrected without etc fstab fsck options potential problem to the file system or files.

While checking connectivity fsck finds some inodes which are allocated but not referenced — not attached to any directory.

If the file is found to be correct it can be used after copying to some other directory and renaming it. Your email address will not be published. Notify me of follow-up comments by email.

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linux - Recommended fstab settings - Unix & Linux Stack Exchange

Interactive fsck examines the file system and stops at each error it finds in the file system and gives the problem description and ask for user response whether to correct the problem or continue without making any change to the file system. Non interactive fsck tries to repair all the problems it finds in a file system without stopping for user response useful in case of a large number of inconsistencies in a file system but has the disadvantage of removing some useful files which are detected to be corrupt.

But forex volume by hour still file system has problems the system boots in single user mode asking for user to manually run the fsck to correct the problems in file system Running fsck fsck can make big changes to the file system by truncating file, re-allocating inodes and making many other adjustmentsit may render many files as useless so use a due caution and respond to fsck prompt carefully.

Corrupted superblock — fsck fails to run If the superblock is corrupted the file system still can be repaired using alternate superblock which are formed while making new file system. Link counter adjustment fsck finds mismatch between directory inode link counts and actual directory links and prompts for adjustment in case of interactive operation.

Free Block count salvage During fsck the number of free blocks listed in a superblock and actual unallocated free blocks count does not match. Unreferenced file reconnection While checking connectivity fsck finds some inodes which are allocated but not referenced — not attached to any directory.

Linux fsck command help and examples

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What is in fsck section in fstab? - Unix & Linux Stack Exchange

Collection of helpful external links related to unix, solaris and system administration. Some tech tips that can save you a lot of timeone liner scriptsfind system information etc.

A unix command tutorial with some of the most popular and useful commands used in unix operating system arranged by functionality.

How to install Solaris OS - Introduction to the procedure and sequence of event in Solaris installation. Learn about syntax running phases and troubleshooting with fsck. The firmware in Sun's boot PROM is called OpenBoot.