topic disable barrier support in Operating System - Linux

disable barrier support

Tehrani_1 — Fri, 11 Aug 2006 03:50:05 GMT

Hello all,

I get the following error when mounting reiserfs Filesystems or during boot

reiserfs: using flush barriers
reiserfs: disabling flush barriers on dm-2

Therefore i put the following kernel option in /boot/grub/menu.lst

barrier=off

So get i rid off this message.

I don't know what barrier support is.
Shall i switch back to the default value ?

I'm running SLES 9 SP3 kernel 2.6.5-7.244-smp on

Thanks in advance
Rgds

Uli

Re: disable barrier support

Atul Gautam — Fri, 11 Aug 2006 08:52:54 GMT

Hi Uli....

As you have mentioned that you have ReiserFS on your machine and while mounting you get an error to flush barriers so you have switched off the barriers.

SuseLinux ES9 provides you with maximum data integrity guarantee by enforcing barriers from the filesystem.

Although without it, while journaling....the system lacks control that they need over the order in which data is written onto the disk. And at times, mis-ordered writes can lead to data corruption and other unfortunate things.

So, it depends on you whether you want to activate it or you want to deactivate it to avoid the error messages.......

So, what I would suggest is that in the "/etc/fstab" file or whatever you have, you can probably specify an option which is "barrier=flush".

--
Atul

Re: disable barrier support

Bernhard J. Dreher — Mon, 25 Sep 2006 07:12:42 GMT

Hello,

I've the same kind of message in dmesg on a SLES9 (Kernel 2.6.5-7.276) System.

reiserfs: using flush barriers
reiserfs: disabling flush barriers on cciss/c0d0p8
reiserfs: using flush barriers
reiserfs: disabling flush barriers on cciss/c0d0p10
reiserfs: using flush barriers
reiserfs: disabling flush barriers on cciss/c0d0p7
reiserfs: using flush barriers
reiserfs: disabling flush barriers on cciss/c0d0p11
reiserfs: using flush barriers
reiserfs: disabling flush barriers on cciss/c0d0p9
reiserfs: using flush barriers
reiserfs: disabling flush barriers on cciss/c0d0p5
reiserfs: using flush barriers
reiserfs: disabling flush barriers on cciss/c0d0p6

My question: Wy does the system disable the flush barriers?
I found nothing in my fstab.

thanks in advance
regards
Bernie