Hello there, I was wondering if anyone has encountered the same problem with the Multipath Extension Module and if this behaviour can be changed.

We have several ESXi hosts with iSCSI MPIO configured pointing to a PS6210 group with redundant controllers and NICs. The configuration is by the book: with 2 vmkernel adapters configured on the same vswitch on separate portgroups, everything on a /24 and multipath works.. kind of (and this is where things get interesting):

We see 2 paths per disk - one for each storage controller IP in active/active, all green. Not bad, but we expect to see 4 paths: 2 for every NIC configured for every storage controller interface. 

Here is a sample diagram:

We initially thought this to be an iSCSI discovery problem, but even after setting the volumes as static targets (with both controller NICs as targets) we only see 2 paths per disk. After re-scanning the HBA, 4 paths per EQL disks appear, but half of them simply go away in a few seconds. When the disk MPIO is configured to use VMWare's module all 4 paths stay in the table.

 

Looking at the ehcmd.log it seems that the MEM is deleting the extra paths:

20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1793|>>>> Reconfiguration Request IPC for iqn.2001-05.com.equallogic:4-771816-fcd89ea46-97a005a202c568a9-ds-eng >>>>
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1795|Opcode: 2827
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1796|MPIO session: 8-f6d95f-427f1d8f2-4c60a182005e1059
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1797|Volume PsvId: 4-771816-fcd89ea46-97a005a202c568a9
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1798|Configuration Options: 0x0
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1799|MaxVolumeConnection: 6
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1800|MaxMemberConnection: 4
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1801|AdapterCount: 2
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1802|ConnectionCount: 4
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1806|adapter[0].HostIndex: 1
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1807|adapter[0].addr: 10.10.10.201
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1808|adapter[0].mask: 255.255.255.0
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1809|adapter[0].speed: 10000
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1810|adapter[0].weight: 0
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1811|adapter[0].ConnectionCount.MpioSession: 2
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1812|adapter[0].ConnectionCount.Total: 7
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1813|adapter[0].HBA.MaxConnTotal: 4092
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1814|adapter[0].HBA.MaxConnSession: 0
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1806|adapter[1].HostIndex: 3
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1807|adapter[1].addr: 10.10.10.202
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1808|adapter[1].mask: 255.255.255.0
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1809|adapter[1].speed: 10000
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1810|adapter[1].weight: 0
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1811|adapter[1].ConnectionCount.MpioSession: 2
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1812|adapter[1].ConnectionCount.Total: 7
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1813|adapter[1].HBA.MaxConnTotal: 4092
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1814|adapter[1].HBA.MaxConnSession: 0
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1819|connection[0].saddr: 10.10.10.201
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1820|connection[0].taddr: 10.10.10.1
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1821|connection[0].sport: 34041
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1822|connection[0].tport: 3260
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1819|connection[1].saddr: 10.10.10.202
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1820|connection[1].taddr: 10.10.10.2
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1821|connection[1].sport: 16240
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1822|connection[1].tport: 3260
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1819|connection[2].saddr: 10.10.10.202
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1820|connection[2].taddr: 10.10.10.1
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1821|connection[2].sport: 62917
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1822|connection[2].tport: 3260
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1819|connection[3].saddr: 10.10.10.201
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1820|connection[3].taddr: 10.10.10.2
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1821|connection[3].sport: 45011
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigReq|1822|connection[3].tport: 3260
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1829|<<<< Reconfiguration Response IPC <<<<
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1830|Opcode: 2828
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1831|MPIO session: 8-f6d95f-427f1d8f2-4c60a182005e1059
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1832|Volume PsvId: 4-771816-fcd89ea46-97a005a202c568a9
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1833|WKA: 10.10.10.100:48140
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1834|Status: 0
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1835|Ext Status: 0x8
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1836|ConnCount: 2
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1848|10.10.10.202 -> 10.10.10.1:3260
20Aug19:11:03:16:EHCMD:INFO|PrintReconfigRsp|1848|10.10.10.201 -> 10.10.10.2:53456
20Aug19:11:03:16:EHCMD:INFO|ProcessReconfigResponse|1778|Total number of sessions changed (original 4, new 2)
20Aug19:11:03:16:EHCMD:INFO|Logout|307|Result of logout: 0x0
20Aug19:11:03:16:EHCMD:INFO|Reconfigure|778|Existing iSCSI session removed successfully
20Aug19:11:03:16:EHCMD:INFO|Logout|307|Result of logout: 0x0
20Aug19:11:03:16:EHCMD:INFO|Reconfigure|778|Existing iSCSI session removed successfully
20Aug19:11:03:16:EHCMD:INFO|GetActiveSessionCount|823|Found 2 sessions
20Aug19:11:03:16:EHCMD:INFO|WaitForNSessions|850|Found expected number of active sessions
20Aug19:11:03:16:EHCMD:INFO|Reconfigure|849|Reconfiguration complete
20Aug19:11:03:16:EHCMD:INFO|operator()|293|Deleting stale deferred request for ScsiId 4-771816-fcd89ea46-97a005a202c568a9 Lun 0x0
20Aug19:11:03:16:EHCMD:INFO|enqueue|231|scheduled job JOB_TYPE_CONNECTION_SETUP_NORMAL to run in 240 sec
20Aug19:11:03:16:EHCMD:INFO|ProcessDeviceChange|871|Processing PSP change for ScsiId 4-771816-fcd89ea46-97a005a202c568a9 PsvId 4-771816-fcd89ea46-97a005a202c568a9 (2 paths) MpioSessionId 8-f6d95f-427f1d8f2-4c60a182005e1059
20Aug19:11:03:16:EHCMD:INFO|IoctlUpdate|1144|IOCTL reports Created:0 Added:0 Removed:2
20Aug19:11:03:16:EHCMD:INFO|IoctlUpdate|1149|EHCM counts Created:0 Added:0 Removed:2

 

Why is this a big deal? We have several target disks and hosts, and the way the EHCMD selects the connection to keep seems to be random. Because of this if the paths are traversing through the SAN switching (with only one layer of SAN switches) and we have a switch lockup or vlan failure (a failure that doesn't cause the switch ports' status to change) we lose the access to a random number of disks.

We are not on the latest fw or MEM, but I wanted to ask if anyone on the latest version has experienced the same issue? How many paths do you have per target/NIC? Is this configurable in the MEM?

 

Maybe the way forward is to isolate the 2 sides of the SAN with VLANs, however dell recommends the 2 switches to be stacked or LAG-d together.