Emerson/Liebert DSE CRAC - dropping connection in DCE

[DCIM_Support]

Hi. 

I am using DCE 7.2.6 and have 10 Emerson/Liebert DSE CRAC units. All have the same webcard model.

The units run a lead/lag configuration on weekly basis and whenever they switch, DCE looses connectivity to those units even though their webcards remain online and accessible via the browser. 

I have tried rebooting the webcards in the units and then requesting a rescan within DCE with no luck. The only way to get them back 'online' in DCE is to reboot the DCE server itself.  This is not a long-term solution, is there a way to keep the connection between DCE and CRACs or re-establish it automatically?

thanks.

(CID:93913911)

[DCIM_Support]

Hi Edward, welcome to the community! We will investigate the issue. It might take more time to reply than usual, because of Christmas holiday. Stay tuned.

(CID:93913995)

[DCIM_Support]

Hi Edward,

I'm not sure what happens when the devices switch? However it seems like they might be offline/stop reporting for a short while? It is a bit strange they do not reestablish connection once back?

I expect they are reporting using SNMP?

I would recommend trying to maybe increase the timeout value on the devices that are impacted.

Choose the affected device(s) and in the top menu bare choose "Device"->"SNMP Device communication Settings"->"Device Scan Settings"  that will show a menu where timeout and retries can be configured.

(CID:93913997)

[DCIM_Support]

Hello,

Are there any other recommendation on this issue.  Our current workaround is to use SNMP1.  This seems to only be an issue when scanning via SNMP3.

(CID:126880223)

[DCIM_Support]

Hi.

All devices are setup to use SNMP v.3 to communicate with DCE.

There are two different scenarios I am dealing with. Scenario 1: the lead/lag units change their roles. In this case the devices never lose power and the web cards always remain online. 

Scenario 2: during a generator test, all CRAC units temporarily lose power (outage lasts about 1 minute) so the internal web cards go offline until power is restored.

in both scenarios DCE will loose communication with the devices and I have to reboot the DCE server to re-establish connectivity. I took your suggestions and increased the timeout value to the max of 60 seconds (and picked 5 retries).  Will keep monitoring to see if this makes any difference.

One other thing, if any changes are made to the config of the web card inside the CRAC unit, it requires a reboot, and it takes about 4 minutes and 20 seconds for the card to fully re-initialize. I tested the new timeout settings against this reboot on about half the units, and in all cases DCE lost communication to that CRAC. 

(CID:93914109)

[DCIM_Support]

Hi Edward, Thanks for trying this out. Sorry to hear it did not solve the issue. Could you elaborate a bit on how the devices are connected to the DCE? Are they connected to the private LAN? or public LAN? Are they using DHCP/BootP/Static IP? When the DCE server is restarted are the devices connected to DCE using the same IP or are they rediscovered? Scenario 1: How did you verify the device is always online? Did you try to have a ping towards the devices running while they switch roles? Scenario 2: It seems it is not possible to make DCE not detect the webcard "outage". It might be possible to adjust the "communication lost" alarm it self in order not to get this reported. I will need to investigate that.

(CID:93914174)

[DCIM_Support]

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