Netapp SAN in ALUA mode has intermittent storage hangs on Red Hat Enterprise Linux 5
Issue
-
Seeing all sorts of errors and strange results when configuring disk under Multipath. A lot of times we are seeing timeouts of 300 seconds, or errors from mpath_prio_alua. We've also tried configuring the disks using ontap, and have seen similar results.
- For example, from the messages log:
kernel: sd 1:0:0:215: timing out command, waited 300s multipathd: /sbin/mpath_prio_alua exitted with 4 multipathd: error calling out /sbin/mpath_prio_alua /dev/sdg- Sometimes multipath fails to create all paths in a device correctly at boot time:
360a98000375374573624424e59726c49 dm-18 NETAPP,LUN [size=60G][features=1 queue_if_no_path][hwhandler=1 alua][rw] \_ round-robin 0 [prio=50][enabled] \_ 2:0:0:211 sdm 8:192 [active][ready] <--- Only 1 path per path-group, instead of the expected 2 \_ round-robin 0 [prio=10][enabled] \_ 1:0:0:211 sdc 8:32 [active][ready] <--- Only 1 path per path-group, instead of the expected 2- We have these disks aliased in /etc/multipath.conf and sometimes the disks are showing up with the aliases, and sometimes they aren't.
Environment
- Red Hat Enterprise Linux 5 (RHEL5)
- Issue observed on kernel-2.6.18-238.1.1.el5 (RHEL5 update 6). Unknown if other versions are affected.
- Netapp SAN (Vendor:Netapp; Model: SAN)
- Configured in alua mode (default is ontap)
- SAN Controller Firmware is prior to
1.11A5.
- device-mapper-multipath
- The following modifications to the default device-mapper-multipath configuration (to support alua-mode):
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout "/sbin/mpath_prio_alua /dev/%n"
hardware_handler "1 alua"
- Emulex HBA (but other HBA brands could also be affected).
- Although there are 2 HBA's connected to the storage, all errors occur through only 1 HBA.
- Issue may be seen on multiple Red Hat Enterprise Linux hosts connecting to the same SAN port.
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