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PCS7 client fails to switch over when using redundant OS Servers

Created by: soikel at: 8/20/2008 6:09 AM (6 Replies)

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8/20/2008 6:09 AM	Rate (0)
soikel Experienced Member Joined: 5/23/2006 Last visit: 9/12/2024 Posts: 16 Rating: (4)	Using PCS7OS Servers withWinCC redundancy, multiple OS clients. Also using preferred server so half of clientsattach to serverA, other half to ServerB. Scenario - ServerA's cpu load pegs to near 100% (for this scenario ignore the reason as to why it pegs). When this happens all clients attached to serverA showbad data. However, sinceWinCC is actually still running on ServerA(althoughslowly because of the cpu load), the clients don't switch toServerB.So clients are rendered useless since they show bad data but do not switch. Does anyone have any insight into the switching methodology? Is it possible to set up some type of watchdogso the client looks at more than WInCC running as the health flag? Another nicety would be to allow clients to switch servers independently from one another, perhaps via a pushbutton. One useful purposeisthe operatorcouldperiodically switch servers to verify functionality of eachclient/server connection. Right now if I want all clientstoswitch I have todisconnect the NIC cable from the server. Don't have a way to switch an individual client.
	Last edited by: soikel at: 8/20/2008 6:11 AM
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8/20/2008 7:24 AM	Rate (0)
Dorftrottel? Silver Member Joined: 8/10/2006 Last visit: 8/13/2024 Posts: 298 Rating: (29)	Point half your clients to the primary server, half of them to the secondary. At least then you will have some visibility between the two sets. I don't know the actual checks being done by PCS7 for the health/uptime of the servers - I don't believe it's just checking whether WinCC is active. I have seen other network upsets caused by Windows where it prevents the clients from switching between the servers. I don't know if using the serial or ethernet redundancy cable between the servers would help. No, it's not OK to ignore why the CPU utilization ramps to some high percentage. If it's because of PCS7 and SQL Server, then you probably are attempting to do too much - archiving or whatever. In that case, I would break out to another set of servers. If it's something else, well then you need to move that process off the server. There are utilities that will force a reboot if your utilization exceeds a certain level for a specified time - that would most certainly cause a client switch.
	Last edited by: Dorftrottel at: 8/20/2008 7:26 AM
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8/26/2008 10:44 AM	Rate (0)
Jaapie Gold Member Joined: 1/17/2006 Last visit: 11/22/2024 Posts: 800 Rating: (63)	Hi Dorftrottel,I have also this experience of not switching to the other server when the “bad” servers cpu load is 100%. I solved it in two steps. 1-using a seriel cable between the two servers and reconfigure the redundant settings so the server has less sync data.2-debugging the real problem of the 100% load of the server (the DCF-clock software was hanging the system).Problem solved.Good luck,

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8/26/2008 2:16 PM	Rate (0)
PADutch Posts: 1 Rating: (0)	May I ask you how to reconfigure the redundant settings so the server has less sync data?
PADutch Posts: 1 Rating: (0)
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8/28/2008 8:03 AM	Rate (0)
Jaapie Gold Member Joined: 1/17/2006 Last visit: 11/22/2024 Posts: 800 Rating: (63)	Hi PADutch, In WinCC on both serversr go to the properties of the redundancy. In this dialog you can check and uncheck some options e.g. "switching when connections fails". The help explains alot on this point. You just have to minimize the data synchronisation to the right extend. Succes, Jaap

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1/28/2013 5:42 PM	Rate (0)
mattman Posts: 3 Rating: (0)	How did you find out the clock was hanging the system up? We are having some intermittent problems with the CPU going to 100% as well. When it does, the entire system becomes useless. Our project is not that big, but something is very wrong. It would be interesting if that was it.
mattman Posts: 3 Rating: (0)
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1/29/2013 9:29 AM	Rate (0)
Silent Bob Posts: 836 Rating: (100)	Can you please check wich tasks are causing the hight CPU load. To exclude the clock you could just disconenct it for a while....
Silent Bob Posts: 836 Rating: (100)
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