NAME | SYNOPSIS | DESCRIPTION | FILES | ATTRIBUTES | SEE ALSO | DIAGNOSTICS
The in.mpathd daemon performs Network Interface Card (NIC) failure and repair detection. In the event of a NIC failure, it causes IP network access from the failed NIC to failover to a standby NIC, if available, or to any another operational NIC that has been configured as part of the same network multipathing group. Once the failed NIC is repaired, all network access will be restored to the repaired NIC.
The in.mpathd daemon detects NIC failure and repair by sending and receiving ICMP echo requests and replies on each NIC. The in.mpathd daemon sends the probes to on-link routers. If no routers are available, it sends the probes to neighboring hosts. Thus, for network failure detection and repair, there must be at least one neighbor on each link that responds to ICMP echo request probes.
in.mpathd needs a special test address on each NIC for the purpose of sending and receiving probes on each NIC. Use the ifconfig command -failover option to configure these test addresses. See ifconfig(1M). The test address must belong to a subnet that is known to the hosts and routers on the link.
in.mpathd works on both IPv4 and IPv6. If IPv4 is plumbed on a NIC, an IPv4 test address is configured on theNIC, and the NIC is configured as part of a network multipathing group, then in.mpathd will start sending ICMP probes on the NIC using IPv4.
In the case of IPv6, the link-local address must be configured as the test address. The in.mpathd daemon will not accept a non-link-local address as a test address. If the NIC is part of a multipathing group, and the test address has been configured, then in.mpathd will probe the NIC for failures using IPv6.
Even if both the IPv4 and IPv6 protocol streams are plumbed, it is sufficient to configure only one of the two, that is, either an IPv4 test address or an IPv6 test address on a NIC. If only an IPv4 test address is configured, it probes using only ICMPv4. If only an IPv6 test address is configured, it probes using only ICMPv6. If both type test addresses are configured, it probes using both ICMPv4 and ICMPv6.
The in.mpathd daemon accesses three variable values in /etc/default/mpathd: FAILURE_DETECTION_TIME, FAILBACK and TRACK_INTERFACES_ONLY_WITH_GROUPS.
The FAILURE_DETECTION_TIME variable specifies the NIC failure detection time. The shorter the failure detection time, the greater the volume of probe traffic. The default value of FAILURE_DETECTION_TIME is 10 seconds. This means that NIC failure will be detected by in.mpathd within 10 seconds. The NIC repair detection time cannot be configured; however, it is defined as double the value of FAILURE_DETECTION_TIME.
By default, in.mpathd does failure detection only on NICs that are configured as part of a multipathing group. You can set TRACK_INTERFACES_ONLY_WITH_GROUPS to no to enable failure detection by in.mpathd on all NICs, even if they are not part of a multipathing group. However, in.mpathd cannot do failover from a failed NIC if it is not part of a multipathing group.
The in.mpathd daemon will restore network traffic back to the previously failed NIC, after it has detected a NIC repair. To disable this, set the value of FAILBACK to no in /etc/default/mpathd.
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE | ATTRIBUTE VALUE |
---|---|
Availability | SUNWcsr |
Every test address that is configured must be unique on the system. Otherwise in.mpathd cannot do failure detection. Since the IPv6 test address is a link-local address, which in turn is derived from the ethernet address, each NIC must have a unique MAC address.
All NICs in a multipathing group must be homogeneously plumbed. For example, if a NIC is plumbed for IPv4, then all NICs in the group must be plumbed for IPv4. The streams modules pushed on all NICs must be identical.
Every NIC that is configured as part of a multipathing group must have a test address, which can be either IPv4 or IPv6, or both. Otherwise in.mpathd cannot probe the NIC, and this message is displayed.
An invalid value was encountered for FAILURE_DETECTION_TIME in the /etc/default/mpathd file.
The minimum value that can be specified for FAILURE_DETECTION_TIME is currently 100 milliseconds.
Valid values for the boolean variable FAILBACK are yes or no.
Valid values for the boolean variable TRACK_INTERFACES_ONLY_WITH_GROUPS are yes or no.
The round trip time for ICMP probes is higher than the specified failure detection time. The network is probably congested or the probe targets are loaded. in.mpathd automatically increases the failure detection time to whatever it can achieve under these conditions.
The round trip time for ICMP probes has now decreased and in.mpathd has lowered the failure detection time correspondingly.
in.mpathd has detected NIC failure on interface_name, and has set the IFF_FAILED flag on NIC interface_name.
in.mpathd has caused the network traffic to failover from NIC interface_name1 to NIC interface_name2, which is part of the multipathing group.
in.mpathd has detected that NIC interface_name is repaired and operational. If the IFF_FAILED flag on the NIC was previously set, it will be reset..
in.mpathd has restored network traffic back to NIC interface_name, which is now repaired and operational.
NAME | SYNOPSIS | DESCRIPTION | FILES | ATTRIBUTES | SEE ALSO | DIAGNOSTICS