RHBA-2014:1555 - Bug Fix Advisory

Topic

Updated device-mapper-multipath packages that fix several bugs and add various
enhancements are now available for Red Hat Enterprise Linux 6.

Description

The device-mapper-multipath packages provide tools for managing multipath
devices using the device-mapper multipath kernel module.

This update fixes the following bugs:

• When running a command on a specific device, the multipath utility did not

accept device specification using the major:minor format. This bug has been
fixed, and a multipath device can now be associated with the multipath command
using a path device major:minor specification. (BZ#1009061)

• Previously, the readsector0 checker did not consider the blocksize when

calculating the number of blocks to read, which led to readsector0 reading too
much on 512 byte devices causing device errors. With this update, readsector0
considers the device blocksize when calculating the amount to read, and 512 byte
devices now work with the readsector0 checker as intended. (BZ#1027061)

• Prior to this update, the code that handles multipathd sysfs devices could

free a
device structure while other data still pointed to it. As a consequence, the
multipathd daemon could occasionally experience use-after-free memory corruption
leading to unexpected termination. The sysfs device handling code for multipathd
has been rewritten, and multipathd no longer frees sysfs device memory while it
is still in use. (BZ#1049637)

• Some of multipathds prioritizers run scsi commands with long timeouts. These

prioritizers do not run asynchronously and multipathd becomes busy waiting for
one to timeout. Consequently, the multipathd daemon can become unresponsive for
as long as 5 minutes when a path fails. With this update, the prioritizers use
the "checker_timeout" option to configure their timeout. Now, prioritizer
timeouts can be adjusted using the checker_timeout option to prevent multipathd
hangs. (BZ#1078485)

• When a multipath device was reloaded outside the multipathd daemon and

existing paths were removed from the device, mutipathd still treated them as
belonging to a multipath device. Consequently, multipathd tried to access a
non-existent path_group and terminated unexpectedly. With this update,
multipathd correctly disassociates removed paths and no longer crashes when
existing paths are removed by external programs. (BZ#1080052)

• If the multipathd daemon failed to add a path to the multipath device table,

the path was incorrectly orphaned. As a consequence, the multipath utility
treated the path as belonging to a multipath device, and multipathd could keep
attempting to switch to a non-existent path_group. The underlying source code
has
been fixed, and multipathd now correctly orphans paths that cannot be added to
the multipath device table. (BZ#1086417)

In addition, this update adds the following enhancements:

• This update adds the force_sync multipath.conf option. Setting force_sync to

"yes" keeps the multipathd daemon from calling the path checkers in asynchronous
mode, which forces multipathd to run only one checker at a time. In addition,
with this option set, multipathd no longer takes up a significant amount of CPU
when a large number of paths is present. (BZ#1054747)

• Previously, the default path ordering often led to the Round Robin path

selector picking multiple paths to the same controller, reducing the performance
benefit from multiple paths. With this update, multipath reorders device paths
in order to alternate between device controllers, leading to a performance
improvement. (BZ#1088013)

• This update adds iscsi support for the "fast_io_fail_tmo" option to allow the

user to modify the speed of multipath responding to failed iscsi devices.
(BZ#1099932)

• With this update, "-w" and "-W" options have been added to multipath; the "-w"

option removes the named WWID from the wwids file, the "-W" option removes all
WWIDs from the wwids file except for the WWIDs of the current multipath devices.
(BZ#1101101)

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/site/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 997570 - multipath may hang if tur checker thread becomes unresponsive
• BZ - 1049637 - multipathd encounters memory corruption
• BZ - 1072974 - typo in ALUA prioritizer error message
• BZ - 1086417 - multipathd stuck trying to switch to group that does not exist
• BZ - 1095868 - Typo in multipathd man page
• BZ - 1099932 - multipath: make fast_io_fail work for iscsi devices

CVEs

(none)

References

(none)