[ovirt-devel] Wrong default multipath configuration for EL6

[Patrick Hurrelmann]

Hi all,

after suffering from boot-failures after kernel-updates on my EL6 hosts
(the ones that san boot via iscsi), I finally managed to locate the root
cause of the problem: the default values as set by vdsm are incorrect
for EL6 and prohibit a successful iscsi boot (the faulty multipath.conf
 gets embedded in the new initrd on a kernel update). Additionally the
following errors are repeatedly logged on all my hosts (device ids may
vary) with the default vdsm multipath config:

device-mapper: table: 253:5: multipath: error getting device
device-mapper: ioctl: error adding target to table
device-mapper: table: 253:5: multipath: error getting device
device-mapper: ioctl: error adding target to table

And it all boils down to the default value set for option getuid_callout
in multipath.conf. Vdsm sets it to the following:

getuid_callout  "/sbin/scsi_id --whitelisted --replace-whitespace
--device=/dev/%n"

According to the man-page and other docu the default value on EL6 is
"/lib/udev/scsi_id --whitelisted --device=/dev/%n". Although the binary
/sbin/scsi_id is a valid link to the target /lib/udev/scsi_id, the link
itself (/sbin/scsi_id) is _not_ included in the generated initrd. The
binary /lib/udev/scsi_id is indeed included and changing the default
config to use /lib/udev/scsi_id instead does make it all work again.
iscsi boot (after regenerating the initrd, as the multipath.conf is
embedded) is back to good and the previously logged device-mapper errors
are gone, too.

Can someone please verify this and and apply the easy (attached) patch?

--- multipath.py.orig	2014-07-29 15:24:37.643839169 +0200
+++ multipath.py	2014-07-29 15:25:06.823840362 +0200
@@ -88,9 +88,8 @@
 log = logging.getLogger("Storage.Multipath")

 _scsi_id = utils.CommandPath("scsi_id",
-                             "/sbin/scsi_id",  # EL6
                              "/usr/lib/udev/scsi_id",  # Fedora
-                             "/lib/udev/scsi_id",  # Ubuntu
+                             "/lib/udev/scsi_id",  # EL6, Ubuntu
                              )



Thanks a lot and best regards
Patrick

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