System Administration Commands in.mpathd(1M) NAME in.mpathd - IP multipathing daemon SYNOPSIS /usr/lib/inet/in.mpathd DESCRIPTION The *in.mpathd* daemon performs failure and repair detection for IP interfaces that have been placed into an IPMP group (or optionally, for all IP interfaces on the system). It also controls which IP interfaces in an IPMP group are "active" (being used by the system to send or receive IP data traffic) in a manner which is consistent with the administrator's configured policy. The *in.mpathd* daemon can detect IP interface failure and repair through two methods: by monitoring the *IFF_RUNNING* flag for each IP interface (link-based failure detection), and by sending and receiving ICMP probes on each IP interface (probe-based failure detection). Link-based failure detection is instantaneous and is always enabled (provided the network driver supports the feature); probe-based failure detection must be enabled through the configuration of one or more test addresses (described below), but tests the entire IP interface send and receive path. The *ipmpstat(1M)* utility can be used to check which failure detection methods are enabled. If only link-based failure detection is enabled, then the health of the interface is determined solely from the state of the IFF_RUNNING flag. Otherwise, the interface is con- sidered failed if either of the two methods indicate a failure, and repaired once both methods indicate the failure has been corrected. Not all interfaces in a group need to be configured with the same failure detection methods. As mentioned above, to perform probe-based failure detection *in.mpathd* requires a test address on each IP interface for the purpose of sending and receiving probes. Each address must be marked *NOFAILOVER* (see *ifconfig(1M)*) and *in.mpathd* will be limited to probing targets on the same subnet. Each address may be configured statically or acquired via DHCP. To find targets, *in.mpathd* first consults the routing table for routes on the same subnet, and uses the specified next-hop. If no routes match, it sends all-hosts ICMP probes and selects a subset of the systems that respond. Thus, for probe-based failure detection to operate, there must be at least one neighbor on each subnet that responds to ICMP echo request probes. The *ipmpstat(1M)* utility can be used to display both the current probe target information and the status of sent probes. Both IPv4 and IPv6 are supported. If an IP interface is plumbed for IPv4 and an IPv4 test address is configured then *in.mpathd* will start sending ICMPv4 probes over that IP interface. Similarly, if an IP interface is plumbed for IPv6 and an IPv6 test address is configured then *in.mpathd* will start sending ICMPv6 probes over that IP interface. However, note that *in.mpathd* will ignore IPv6 test addresses that are not link-local. If both IPv4 and IPv6 are plumbed, it is sufficient to configure only one of the two, that is, either an IPv4 test address or an IPv6 test address. If both IPv4 and IPv6 test addresses are configured, *in.pathd* probes using both ICMPv4 and ICMPv6. As mentioned above, *in.mpathd* also controls which IP interfaces in an IPMP group are "active" (used by the system to send and receive IP data traffic). Specifically, *in.mpathd* tracks the administrative configuration of each IPMP group and attempts to keep the number of active IP interfaces in each group consistent with that configuration. Therefore, if an active IP interface fails, *in.mpathd* will activate an *INACTIVE* interface in the group, provided one exists (it will prefer *INACTIVE* interfaces that are also marked *STANDBY*). Likewise, if an IP interface repairs and the resulting repair leaves the IPMP group with more active interfaces than the administrative configuration specifies, *in.mpathd* will deactivate one of the interfaces (preferably one marked *STANDBY*), except when the *FAILBACK* variable is used, as described below. Similar adjustments will be made by *in.mpathd* when offlining IP interfaces (for instance, in response to *if_mpadm(1M)*). 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 probe-based failure detection time. The shorter the failure detection time, the more probe traffic. The default value of *FAILURE_DETECTION_TIME* is 10 seconds. This means that IP interface failure will be detected by *in.mpathd* within 10 seconds. The IP interface repair detection time is always twice the value of *FAILURE_DETECTION_TIME*. Note that failures and repairs detected by link-based failure detection are acted on immediately, though *in.mpathd* may ignore link state changes if it suspects that the link state is flapping due to defective hardware; see DIAGNOSTICS. By default, *in.mpathd* limits failure and repair detection to IP interfaces that are configured as part of a named IPMP group. Setting *TRACK_INTERFACES_ONLY_WITH_GROUPS* to *no* enables failure and repair detection on all IP interfaces, even if they are not part of a named IPMP group. IP interfaces that are tracked but not part of a named IPMP group are considered to be part of the "anonymous" IPMP group. In addition to having no name, this IPMP group is special in that its IP interfaces are not equivalent and thus cannot take over for one another in the event of an IP interface failure. That is, the anonymous IPMP group can only be used for failure and repair detection, and provides no high-availability or load-spreading. As described above, when *in.mpathd* detects that an IP interface has repaired, it activates it so that it will again be used to send and receive IP data traffic. However, if *FAILBACK* is set to *no*, then the IP interface will only be activated if no other active IP interfaces in the group remain. However, the interface may subsequently be activated if another IP interface in the group fails. FILES /etc/default/mpathd Contains default values used by the in.mpathd daemon. ATTRIBUTES See attributes(5) for descriptions of the following attri- butes: ____________________________________________________________ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | |_____________________________|_____________________________| | Availability | SUNWcsr | |_____________________________|_____________________________| SEE ALSO ifconfig(1M), ipmpstat(1M), if_mpadm(1M), icmp(7P), icmp6(7P) DIAGNOSTICS IP interface *interface_name* has a hardware address which is not unique in group *group_name*; offlining Description: For probe-based failure detection, load-spreading, and other code IPMP features to work properly, each IP interface in an IPMP group must have a unique hardware address. If this requirement is not met, *in.mpathd* will automatically offline all but one of the IP interfaces with duplicate hardware addresses. IP interface *interface_name* now has a unique hardware address in group *group_name*; onlining Description: The previously-detected duplicate hardware address is now unique, and therefore *in.mpathd* has brought *interface_name* back online. Test address *address* is not unique in group; disabling probe-based failure detection on *interface_name* Description: For in.mpathd to perform probe-based failure detection, each test address in the group must be unique. SunOS 5.11 Last change: 8 Sep 2006 3 System Administration Commands in.mpathd(1M) No test address configured on interface *interface_name*; disabling probe-based failure detection on it Description: For *in.mpathd* to perform probe-based failure detection on an IP interface, it must be configured with a test address: IPv4, IPv6, or both. NIC interface_name of group group_name is not plumbed for IPv[4|6] and may affect failover capability Description: 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 also be identical. The link has come up on interface_name more than 2 times in the last minute; disabling repair until it stabilizes. Description: To limit the impact of interfaces with intermittent hardware (such as a bad cable), *in.mpathd* will not consider an IP interface with a frequently changing link state as repaired until the link state stabilizes. Invalid failure detection time of *time*, assuming default of 10000 ms Description: An invalid value was encountered for FAILURE_DETECTION_TIME in the /etc/default/mpathd file. Too small failure detection time of *time*, assuming minimum of 100 ms Description: SunOS 5.11 Last change: 8 Sep 2006 4 System Administration Commands in.mpathd(1M) The minimum value that can be specified for FAILURE_DETECTION_TIME is currently 100 milliseconds. Invalid value for FAILBACK value Description: Valid values for the boolean variable FAILBACK are yes or no. Invalid value for TRACK_INTERFACES_ONLY_WITH_GROUPS value Description: Valid values for the boolean variable TRACK_INTERFACES_ONLY_WITH_GROUPS are yes or no. Cannot meet requested failure detection time of time ms on (inet[6] interface_name) new failure detection time for group group_name is time ms Description: The round trip time for ICMP probes is higher than necessary to maintain the current 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. Improved failure detection time time ms on (inet[6] interface_name) for group group_name Description: The round trip time for ICMP probes has now decreased and in.mpathd has lowered the failure detection time correspondingly. IP interface failure detected on interface_name Description: SunOS 5.11 Last change: 8 Sep 2006 5 System Administration Commands in.mpathd(1M) *in.mpathd* has detected a failure on *interface_name*, and has set the *IFF_FAILED* flag on *interface_name*, ensuring that it will not be used for IP data traffic. IP interface repair detected on *interface_name* Description: *in.mpathd* has detected a repair on *interface_name*, and has cleared the *IFF_FAILED* flag. Depending on the administrative configuration, the *interface_name* may again be used for IP data traffic. The link has gone down on interface_name Description: *in.mpathd* has detected that the *IFF_RUNNING* flag for *interface_name* has been cleared, indicating the link has gone down. The link has come up on interface_name Description: *in.mpathd* has detected that the *IFF_RUNNING* flag for *interface_name* has been set, indicating the link has come up. SunOS 5.11 Last change: 8 Sep 2006 6 System Administration Commands in.mpathd(1M) SunOS 5.11 Last change: 8 Sep 2006 7