ecryptfs team mailing list archive

[Theodore Ts'o <tytso@xxxxxxx>]

>One thing is not clear to me theo, I just expect it to. Is it true that memory
>cache, being faster, might also prevent a lot of problems? I got 4Gb on my
>box, might that be an explanation that I'm less likely to encounter problems?

@nyarnon,

No, having more or less memory won't make a difference; the issue here
isn't a matter of being faster or slower, it's about how quickly data
gets pushed out to disk.   Normally the VM subsystem only starts writing
data to disk only after 30 seconds have gone by for performance reasons
--- in case the file gets modified a second time, no point writing it
once, and then a second time 30 seconds later.   How often tihs gets
done is controlled by /proc/sys/vm/dirty_expire_centisecs, and how often
you scan is controlled by /proc/sys/vm/dirty_writeback_centisecs.   The
default for these two values are 3000 (30 seconds) and 500 (5 seconds),
respectively.  These values can be adjusted by laptop_mode (to be
higher), and in fact I've been playing with having these values much
higher (60 minutes and 1 minute), mainly because I wanted to try to
reduce writes to an SSD.

What happened is that ext3 in ordered data mode forced *all* blocks that
were dirty to be pushed out during the next journal commit (which takes
place by default every 5 seconds, more if you have laptop mode turned
on).    So something else you can do is to simply adjust these values
down, in particular the dirty_expire_centisecs, to be something like
300.   I wouldn't do this on a system where I was going to be running
ext4 benchmarks, but it will automatically sync things out more
aggressively.

-- 
Ext4 data loss
https://bugs.launchpad.net/bugs/317781
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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