Ext3 behavior on power failure

armangau_philippe at emc.com armangau_philippe at emc.com
Wed Mar 21 17:18:10 UTC 2007

Hi all,

We are building a new system which is going to use ext3 FS. We would like to know more about the behavior of ext3 in the case of failure.  But before I procede, I would like to share more information about our future system. 

*	Our application always does an fsync on files
*	When symbolic links (more specifically fast symlink) are created, the host directory is also fsync'ed. 
*	Our application is also going to front an EMC disk array configured using RAID5 or RAID6.
*	We will be using multipathing  so that we can assume that no disk errors will be reported. 

In this context , we would like to know the following for recovery after a power outage:

1.	When will an fsck have to be run (not counting  the scheduled fsck every N-mounts)?
2.	In the case of a crash, are the fsync-ed file contents and symbolic links safe no matter what?


Philippe Armangau
Centera Software Group
Consultant Software Engineer

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