ecryptfs team mailing list archive

[Theodore Ts'o <tytso@xxxxxxx>]

@Volodymyr M. Lisivka,

You can opine all you want, but the problem is that POSIX does not
specify anything about "hidden transactions", and certainly does not
make any guarantees like this.   As I said, most modern file systems are
doing delayed allocation for speed reasons, so you can expect this to be
more of a norm.   The patch which is going into 2.6.30 will do this, and
by default, when you are replacing files, mostly because I know most
application programmers are going to continue to rely on this.  However,
it's a bad idea to do so.

If you really care about making sure something is on disk, you have to
use fsync or fdatasync.  If you are about the performance overhead of
fsync(), fdatasync() is much less heavyweight, if you can arrange to
make sure that the size of the file doesn't change often.   You can do
that via a binary database, that is grown in chunks, and rarely
truncated.

I'll note that I use the GNOME desktop (which means the gnome panel, but
I'm not a very major desktop user), and "find .[a-zA-Z]* -mtime 0"
doesn't show a large number of files.  I'm guessing it's certain badly
written applications which are creating the "hundreds of dot files" that
people are reporting become zero lengh, and if they are seeing it happen
a lot, it must be because the dot files are getting updated very
frequently.   I don't know what the bad applications are, but the people
who complained about large number of state files disappearing should
check into which application were involved, and try to figure out how
often they are getting modified.  As I said, if large number of files
are getting frequently modified, it's going to be bad for SSD's as well,
there are multiple reasons to fix badly written applications, even if
2.6.30 will have a fix for the most common cases.  (Although some server
folks may mount with a flag to disable it, since it will cost
performance.)

-- 
Ext4 data loss
https://bugs.launchpad.net/bugs/317781
You received this bug notification because you are a member of eCryptfs,
which is subscribed to ecryptfs-utils in ubuntu.

Status in “ecryptfs-utils” source package in Ubuntu: Invalid
Status in “linux” source package in Ubuntu: Confirmed
Status in ecryptfs-utils in Ubuntu Jaunty: Invalid
Status in linux in Ubuntu Jaunty: Confirmed

Bug description:
I recently installed Kubuntu Jaunty on a new drive, using Ext4 for all my data.

The first time i had this problem was a few days ago when after a power loss ktimetracker's config file was replaced by a 0 byte version . No idea if anything else was affected.. I just noticed ktimetracker right away.

Today, I was experimenting with some BIOS settings that made the system crash right after loading the desktop. After a clean reboot pretty much any file written to by any application (during the previous boot) was 0 bytes.
For example Plasma and some of the KDE core config files were reset. Also some of my MySQL databases were killed...

My EXT4 partitions all use the default settings with no performance tweaks. Barriers on, extents on, ordered data mode..

I used Ext3 for 2 years and I never had any problems after power losses or system crashes.

Jaunty has all the recent updates except for the kernel that i don't upgrade because of bug #315006

ProblemType: Bug
Architecture: amd64
DistroRelease: Ubuntu 9.04
NonfreeKernelModules: nvidia
Package: linux-image-2.6.28-4-generic 2.6.28-4.6
ProcCmdLine: root=UUID=81942248-db70-46ef-97df-836006aad399 ro rootfstype=ext4 vga=791 all_generic_ide elevator=anticipatory
ProcEnviron:
 LANGUAGE=
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.28-4.6-generic
SourcePackage: linux