CitectSCADA and VMWare snapshot backup

Hello everyone,

We are using CitectSCADA 2016 with two redundant servers. Each server is running in a virtual machine (VMWare). Everything works fine except that sometimes (about once or twice a week), the backup server takes control for a few seconds (the IODevices switch to the standby) and then the go back to the primary server. Since this always happens between 22h30 and 23h00, we are trying to find what causes this.

After discussing with our IT department which manage the servers, they do a backup of the VM machines at about those times everyday by doing a "snapshot" of the virtual machine. We are wondering if this could cause a "glitch" on the primary server when this backup is made, which would cause the standby server to not see it for a short period of time and take control.

Has anyone had any similar experiences with VMWare, are there any "best practices" concerning VM configurations and backups when using Citect ?

Thanks for your help,

Patrice Jacob

Prosystech inc.

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  • Hi Patrice,
    We have run Citect on VMware ESXi for several years and I haven't seen a snapshot cause IO devices to failover to the standby. It's likely highly dependent on the physical hardware it is running on and the backup software you are using though - so it's hard to comment.

    Just a small note that if you are using software licenses on these VMs then the licenses will be broken if you try to restore the backup. We're waiting for a better license solution to address this issue.
    Tim Marz
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  • Hi Patrice,
    We have run Citect on VMware ESXi for several years and I haven't seen a snapshot cause IO devices to failover to the standby. It's likely highly dependent on the physical hardware it is running on and the backup software you are using though - so it's hard to comment.

    Just a small note that if you are using software licenses on these VMs then the licenses will be broken if you try to restore the backup. We're waiting for a better license solution to address this issue.
    Tim Marz
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