1in.mpathd(1M) System Administration Commands in.mpathd(1M)
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6 in.mpathd - IP multipathing daemon
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9 /usr/lib/inet/in.mpathd
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13 The in.mpathd daemon performs failure and repair detection for IP
14 interfaces that have been placed into an IPMP group (or optionally, for
15 all IP interfaces on the system). It also controls which IP interfaces
16 in an IPMP group are "active" (being used by the system to send or
17 receive IP data traffic) in a manner that is consistent with the admin‐
18 istrator's configured policy.
19 The in.mpathd daemon can detect IP interface failure and repair through
22 two methods: by monitoring the IFF_RUNNING flag for each IP interface
23 (link-based failure detection), and by sending and receiving ICMP
24 probes on each IP interface (probe-based failure detection). Link-based
25 failure detection is instantaneous and is always enabled (provided the
26 network driver supports the feature); probe-based failure detection
27 must be enabled through the configuration of one or more test addresses
28 (described below), but tests the entire IP interface send and receive
29 path. The ipmpstat(1M) utility can be used to check which failure
30 detection methods are enabled.
31 If only link-based failure detection is enabled, then the health of the
34 interface is determined solely from the state of the IFF_RUNNING flag.
35 Otherwise, the interface is considered failed if either of the two
36 methods indicate a failure, and repaired once both methods indicate the
37 failure has been corrected. Not all interfaces in a group need to be
38 configured with the same failure detection methods.
39 As mentioned above, to perform probe-based failure detection in.mpathd
42 requires a test address on each IP interface for the purpose of sending
43 and receiving probes. Each address must be marked NOFAILOVER (see
44 ifconfig(1M)) and in.mpathd will be limited to probing targets on the
45 same subnet. Each address may be configured statically or acquired by
46 means of DHCP. To find targets, in.mpathd first consults the routing
47 table for routes on the same subnet, and uses the specified next-hop.
48 If no routes match, it sends all-hosts ICMP probes and selects a subset
49 of the systems that respond. Thus, for probe-based failure detection to
50 operate, there must be at least one neighbor on each subnet that
51 responds to ICMP echo request probes. The ipmpstat(1M) utility can be
52 used to display both the current probe target information and the sta‐
53 tus of sent probes.
54 Both IPv4 and IPv6 are supported. If an IP interface is plumbed for
57 IPv4 and an IPv4 test address is configured then in.mpathd will start
58 sending ICMPv4 probes over that IP interface. Similarly, if an IP
59 interface is plumbed for IPv6 and an IPv6 test address is configured,
60 then in.mpathd will start sending ICMPv6 probes over that IP interface.
61 However, note that in.mpathd will ignore IPv6 test addresses that are
62 not link-local. If both IPv4 and IPv6 are plumbed, it is sufficient to
63 configure only one of the two, that is, either an IPv4 test address or
64 an IPv6 test address. If both IPv4 and IPv6 test addresses are config‐
65 ured, in.mpathd probes using both ICMPv4 and ICMPv6.
66 As mentioned above, in.mpathd also controls which IP interfaces in an
69 IPMP group are "active" (used by the system to send and receive IP data
70 traffic). Specifically, in.mpathd tracks the administrative configura‐
71 tion of each IPMP group and attempts to keep the number of active IP
72 interfaces in each group consistent with that configuration. Therefore,
73 if an active IP interface fails, in.mpathd will activate an INACTIVE
74 interface in the group, provided one exists (it will prefer INACTIVE
75 interfaces that are also marked STANDBY). Likewise, if an IP interface
76 repairs and the resulting repair leaves the IPMP group with more active
77 interfaces than the administrative configuration specifies, in.mpathd
78 will deactivate one of the interfaces (preferably one marked STANDBY),
79 except when the FAILBACK variable is used, as described below. Similar
80 adjustments will be made by in.mpathd when offlining IP interfaces (for
81 instance, in response to if_mpadm(1M)).
82 The in.mpathd daemon accesses three variable values in
85 /etc/default/mpathd: FAILURE_DETECTION_TIME, FAILBACK and TRACK_INTER‐
86 FACES_ONLY_WITH_GROUPS.
87 The FAILURE_DETECTION_TIME variable specifies the probe-based failure
90 detection time. The shorter the failure detection time, the more probe
91 traffic. The default value of FAILURE_DETECTION_TIME is 10 seconds.
92 This means that IP interface failure will be detected by in.mpathd
93 within 10 seconds. The IP interface repair detection time is always
94 twice the value of FAILURE_DETECTION_TIME. Note that failures and
95 repairs detected by link-based failure detection are acted on immedi‐
96 ately, though in.mpathd may ignore link state changes if it suspects
97 that the link state is flapping due to defective hardware; see DIAGNOS‐
98 TICS.
99 By default, in.mpathd limits failure and repair detection to IP inter‐
102 faces that are configured as part of a named IPMP group. Setting
103 TRACK_INTERFACES_ONLY_WITH_GROUPS to no enables failure and repair
104 detection on all IP interfaces, even if they are not part of a named
105 IPMP group. IP interfaces that are tracked but not part of a named IPMP
106 group are considered to be part of the "anonymous" IPMP group. In addi‐
107 tion to having no name, this IPMP group is special in that its IP
108 interfaces are not equivalent and thus cannot take over for one another
109 in the event of an IP interface failure. That is, the anonymous IPMP
110 group can only be used for failure and repair detection, and provides
111 no high-availability or load-spreading.
112 As described above, when in.mpathd detects that an IP interface has
115 repaired, it activates it so that it will again be used to send and
116 receive IP data traffic. However, if FAILBACK is set to no, then the IP
117 interface will only be activated if no other active IP interfaces in
118 the group remain. However, the interface may subsequently be activated
119 if another IP interface in the group fails.
120
122 /etc/default/mpathd Contains default values used by the in.mpathd
123 daemon.
124
127 See attributes(5) for descriptions of the following attributes:
128 ┌─────────────────────────────┬─────────────────────────────┐
133 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
134 ├─────────────────────────────┼─────────────────────────────┤
135 │Availability │SUNWcsr │
136 └─────────────────────────────┴─────────────────────────────┘
137
139 if_mpadm(1M), ifconfig(1M), ipmpstat(1M), attributes(5), icmp(7P),
140 icmp6(7P),
141 System Administration Guide: IP Services
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146 IP interface interface_name has a hardware address which is not unique
147 in group group_name; offlining
148 Description:
149 For probe-based failure detection, load-spreading, and other code
152 IPMP features to work properly, each IP interface in an IPMP group
153 must have a unique hardware address. If this requirement is not
154 met, in.mpathd will automatically offline all but one of the IP
155 interfaces with duplicate hardware addresses.
156 IP interface interface_name now has a unique hardware address in group
160 group_name; onlining
161 Description:
162 The previously-detected duplicate hardware address is now unique,
165 and therefore in.mpathd has brought interface_name back online.
166 Test address address is not unique in group; disabling probe-based
170 failure detection on interface_name
171 Description:
172 For in.mpathd to perform probe-based failure detection, each test
175 address in the group must be unique.
176 No test address configured on interface interface_name disabling probe-
180 based failure detection on it
181 Description:
182 For in.mpathd to perform probe-based failure detection on an IP
185 interface, it must be configured with a test address: IPv4, IPv6,
186 or both.
187 IP interface_name in group group_name is not plumbed for IPv[4|6],
191 affecting IPv[4|6] connectivity
192 Description:
193 All IP interfaces in a multipathing group must be homogeneously
196 plumbed. For example, if one IP interface is plumbed for IPv4, then
197 all IP interfaces in the group must be plumbed for IPv4, or IPv4
198 packets will not be able to be reliably sent and received. The
199 STREAMS modules pushed on all IP interfaces must also be identical.
200 The link has come up on interface_name more than 2 times in the last
204 minute; disabling repair until it stabilizes.
205 Description:
206 To limit the impact of interfaces with intermittent hardware (such
209 as a bad cable), in.mpathd will not consider an IP interface with a
210 frequently changing link state as repaired until the link state
211 stabilizes.
212 Invalid failure detection time of time, assuming default 10000 ms
216 Description:
217 An invalid value was encountered for FAILURE_DETECTION_TIME in the
220 /etc/default/mpathd file.
221 Too small failure detection time of time, assuming minimum of 100 ms
225 Description:
226 The minimum value that can be specified for FAILURE_DETECTION_TIME
229 is currently 100 milliseconds.
230 Invalid value for FAILBACK value
234 Description:
235 Valid values for the boolean variable FAILBACK are yes or no.
238 Invalid value for TRACK_INTERFACES_ONLY_WITH_GROUPS value
242 Description:
243 Valid values for the boolean variable TRACK_INTER‐
246 FACES_ONLY_WITH_GROUPS are yes or no.
247 Cannot meet requested failure detection time of time ms on (inet[6]
251 interface_name) new failure detection time for group group_name is time
252 ms
253 Description:
254 The round trip time for ICMP probes is higher than necessary to
257 maintain the current failure detection time. The network is proba‐
258 bly congested or the probe targets are loaded. in.mpathd automati‐
259 cally increases the failure detection time to whatever it can
260 achieve under these conditions.
261 Improved failure detection time time ms on (inet[6] interface_name) for
265 group group_name
266 Description:
267 The round trip time for ICMP probes has now decreased and in.mpathd
270 has lowered the failure detection time correspondingly.
271 IP interface failure detected on interface_name
275 Description:
276 in.mpathd has detected a failure on interface_name, and has set the
279 IFF_FAILED flag on interface_name, ensuring that it will not be
280 used for IP data traffic.
281 IP interface repair detected on interface_name
285 Description:
286 in.mpathd has detected a repair on interface_name, and has cleared
289 the IFF_FAILED flag. Depending on the administrative configuration,
290 the interface_name may again be used for IP data traffic.
291 All IP interfaces in group group are now unusable
295 Description:
296 in.mpathd has determined that none of the IP interfaces in group
299 can be used for IP data traffic, breaking network connectivity for
300 the group.
301 At least 1 IP interface (interface_name) in group group is now usable
305 Description:
306 in.mpathd has determined that at least one of the IP interfaces in
309 group can again be used for IP data traffic, restoring network con‐
310 nectivity for the group.
311 The link has gone down on interface_name
315 Description:
316 in.mpathd has detected that the IFF_RUNNING flag for interface_name
319 has been cleared, indicating that the link has gone down.
320 The link has come up on interface_name
324 Description:
325 in.mpathd has detected that the IFF_RUNNING flag for interface_name
328 has been set, indicating that the link has come up.
329SunOS 5.11 13 May 2009 in.mpathd(1M)