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If only a single credential is available for a device (when using Credential Binding, or discovery Discovery with only a single credential added in the "Credentials" screen), Unimus will only open a single CLI session to the device after finding an available connector. Unimus will open connections to multiple devices at the same time (this can be configured as per the Changing maximum job concurrency article), but there will only be a single connection to each of these devices.
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The discovery mechanism is what makes only the address of the device required when adding a new device into Unimus.
Unimus will automatically discovered discover everything else about the device.
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The discovery before backup is necessary to make sure Unimus doesn't user use wrong commands on the device.
In certain situations (ex. when a device is changed for another device) it's possible commands to generate backups on some vendors can actually cause configuration changes for other vendors.
Due to this (and other edge-cases) Unimus does a discovery before every backup.
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