Re: question about possibility of data loss in Ext2/3 file system

From: Sam Vilain
Date: Thu Feb 23 2006 - 14:44:31 EST


Theodore Ts'o wrote:
Also, the scheme you mentioned is just for new file creation. What
will happen if I want to update an existing file? Say, I open file A,
seek to offset 5000, write 4096 bytes, and then close. Do you know how
ext2/3 handle this situation?
If you have a power failure right after the close, the data could be
lost. This is true for pretty much all Unix filesystems, for
performance reasons. If you care about the data hitting disk, the
application must use fsync().

I always liked Sun's approach to this in Online Disk Suite - journal at the block device level rather than the FS / application level. Something I haven't seen from the Linux md-utils or DM.

Sam.
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