Ubuntu

upgrading to multipath 0.4.9 presents incompatible config file changes

Reported by Peter Petrakis on 2011-06-29
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
multipath-tools (Ubuntu)
High
Unassigned

Bug Description

The priority checkers have been converted from individual binaries that callout to dynamically loaded libraries (dlopen). As a result, should a circa 0.4.8 config file remain in place, the priority checker becomes undefined, as that standalone path checker no longer exists. This will effect users who upgrade to Oneiric and users who upgrade from lucid to the next LTS.

One example of the format change is,

0.4.8:
prio_callout "/sbin/mpath_prio_alua /dev/%n"

0.4.9:
prio alua

There may be other config file changes, more exploration is needed.

Here's what the preconfigured, 0.4.9 priority checkers look like.

# echo 'show config' | multipathd -k | grep 'prio '| sort -u
  prio alua
  prio const
  prio emc
  prio hds
  prio hp_sw
  prio netapp
  prio rdac

In 0.4.8:
# echo 'show config' | multipathd -k | grep 'prio_callout'| sort -u
  prio_callout /sbin/mpath_prio_alua /dev/%n
  prio_callout /sbin/mpath_prio_alua %n
  prio_callout /sbin/mpath_prio_emc /dev/%n
  prio_callout /sbin/mpath_prio_hds_modular /dev/%n
  prio_callout /sbin/mpath_prio_hp_sw /dev/%n
  prio_callout /sbin/mpath_prio_netapp /dev/%n
  prio_callout /sbin/mpath_prio_rdac /dev/%n

description: updated
Changed in multipath-tools (Ubuntu):
status: New → Confirmed
Changed in multipath-tools (Ubuntu):
importance: Undecided → High
Peter Petrakis (peter-petrakis) wrote :

Experimenting shows that we can have the older config values side by side
with the new ones. e.g.

...
  prio_callout /sbin/mpath_prio_alua /dev/%n
  prio alua
...

multipath doesn't have a rigid config file format, it seems to slurp symbols
and then seek the key/value pair out on demand. In doing this, we can safely
downgrade as well.

Peter Petrakis (peter-petrakis) wrote :

This has been resolved by updating the documentation in the serverguide.

https://help.ubuntu.com/12.04/serverguide/device-mapper-multipathing.html#multipath-new-and-changed-features

Changed in multipath-tools (Ubuntu):
status: Confirmed → Fix Released
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