JBD error message "barrier-based sync failed"

This document (3907838) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10
SUSE Linux Enterprise Server 9
SUSE Linux Enterprise Desktop 10

Situation

ERROR:JBD: barrier-based sync failed on sda1 - disabling barriers"
or, in general:JBD: barrier-based sync failed onstorage_device- disabling barriers

Resolution

This message is primarily an informational message; it does not indicate a problem.

Suppress this message globally

Please note: This method is only available for SUSE Linux Enterprise Server / Desktop (SLES/SLED) up to version 9. From SLES/SLED 10 on it is not possible to suppress the message globally. Instead use the solution in the section "Suppress this message for one filesystem".

To suppress this message globally, pass the parameter

barrier=off

to the kernel when booting (e.g., when using the GRUB boot loader, through /boot/grub/menu.lst). This will cause the kernel not to attempt to use the transaction barrier mechanism.

Suppress this message for one filesystem

To suppress this message for one particular ext3 filesystem, use the mount option barrier=0 when mounting the filesystem.

Additional Information

Background

By default, the Linux kernel will try to use transaction barriers. Transaction barriers are an additional mechanism to help maintain data integrity. In general, modern storage subsystems may cache writes and may occasionally reorder pending writes in order to increase write performance. While this is fine in general, it is not desirable when handling journal data for journaled filesystems. With journal data, metadata updates, that is updates to the journal, should be written out to the storage prior to the regular data they are associated with, to make true crash recovery possible.

The informational message indicates that the storage driver and/or the storage device do not support transaction barriers. Under normal operation, this does not compromise data integrity. However, barriers help ensure data is correctly written out to the disk.

"JBD" in this message refers to the Journaling Block Device, an abstraction that was developed to provide the journaling capabilities of the ext3 filesystem on top of the infrastructure of the ext2 filesystem on which ext3 is based. JBD is now used by the OCFS2 filesystem as well.

Additional Information:
barrier=1 in filesystems does two independent things:
1) it prevents reordering around the barrier.
2) it causes a cache flush on the storage system. For a shared storage system with many disks this may be undesired, especially if the storage system has a battery-backed cache memory.

For more details on barriers see TID 000017003 "NFS performance drops dramatically after a SLES 10 support pack or SLES 11 install

Disclaimer

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