4.21. device-mapper-multipath

The multipathd daemon creates its private namespace which is supposed to keep only the file systems that are necessary for multipathd to run. However, multipathd did not check every file system in the namespace, and the namespace thus could contain also non-essential file systems. As a consequence, devices containing such file systems could not be removed from the system. With this update, multipathd verifies all file systems in its private namespace and removes every non-essential file system found. The devices containing the non-essential file systems can now be removed as expected when the file systems are unmounted.

If the initrd RAM disk was not rebuilt when a new storage device was added to the system, the new device could be assigned a user_friendly_names value that collided with a value already assigned to another device. Consequently, the original device then stopped working correctly. Now, the multipathd daemon accepts the "-B" option, which makes the user_friendly_names bindings file read-only. When initrd calls multipath with the "-B" option, devices without a binding to a user_friendly_names use their World Wide Identifier (WWID) instead, thus fixing this bug.

The multipathd daemon ignored all subdirectories in /var/lib/ when deciding which file systems to unmount. Now, the only subdirectory of /var/lib/ that multipathd does not unmount is /var/lib/multipath/. Also, multipathd now unmounts all unnecessary file systems before mounting the ramfs on the /tmp/, /bin/, and /sbin/ directories.

If initrd was not rebuilt when a new storage device was added to the system, the new device could have been assigned a user_friendly_names value already assigned to another device, and the device stopped working correctly. multipathd now accepts the -B option, which makes the user_friendly_names bindings file read-only. When started with the -B option, multipath devices without a binding to a user_friendly_names use their World Wide Identifier (WWID).

The multipathd daemon failed to unmount some file systems because the daemon was deleting unnecessary file systems while reading through the list of mounted file systems. Consequently, Multipath could have missed the deleted file systems. The multipathd daemon now reads through all file systems first and creates a list of the file systems to unmount, which are then unmounted based on this list.

The multipathd daemon incorrectly returned exit code 1 when called with the -h option. The deamon now returns exit code 0 when called with the -h option.

The multipathd daemon did not always flush the log buffer if it failed during start-up and error messages logged during start-up could be lost. multipathd now always flushes the log buffer on failures and error messages are logged correctly if multipathd terminates unexpectedly during start-up.

The multipath priority callout programs did not work correctly with CCISS (Compaq Command Interface for SCSI-3 Support) devices because multipath could not convert the ! character in a CCISS sysfs name to the / character in the CCISS device name. Consequently, callout programs failed to set path priorities for these devices. The code has been modified and Multipath now supports the "%c" wildcard for callout functions and the CCISS names are converted correctly.

This update adds the default configuration for HP P2000 G3 MSA Smart Array Systems.

Multiple default settings and parameters have been enhanced: - The multipathd daemon did not set the max_fds option and the user had to manually set the max_fds option in multipath.conf. - Multipath did not disable queuing when it stopped: when multipathd stopped on node shutdown, if a multipath device had no working paths and was set to queue_if_no_path, the device queued outstanding IO forever, rendering the machine unresponsive. - The user_friendly_names option was only configurable in the defaults section and users could not override its value in their device-specific configurations. - A path group with many secondary paths could be used instead of the path group with the primary path by default. This happened because Multipath set the priority of path groups to the sum of their path priorities and used the path group with the primary path instead of using a path group with many secondary paths.

Device Mapper Multipath now sets max_fds to the system maximum, queue_if_no_daemon to the "no", and pg_prio_calc to "average" by default. The user_friendly_names property can be configured in the devices section of multipath.conf.

Configuration for Fujitsu ETERNUS storage systems has been added.

The built-in configuration for NetApp LUNs has been updated to use the tur path checker by default and multiple hardware table parameters have been updated.