Synology Software version 6.2 Discontinues Support for Block-Level iSCSI connections


Synology changes to iSCSI Support break Unitrends iSCSI management for cold copy


Unitrends customers using some models of Synology NAS devices may find that after upgrading to NAS OS release 6.2 Unitrends can no longer connect to the Synology iSCSI devices that may be presented to us.  This will result in un-bootable states and complete data loss if a UB appliance was configured to directly use Synology storage over iSCSI block devices.  This will also result in the inability to connect to cold copy iSCSI block devices and loss of historical copied data. 
This could also result in loss of hypervisor connection to your Synology storage in many configurations rendering UB virtual disks inaccessible.  



Unitrends Appliances only support block-level iSCSI connections for backup storage (for UB Virtual Appliances) or backup copy storage (for either UB or Recovery Series appliances).

Once an affected Synology storage system is updated to release 6.2+ Unitrends will lose connection to prior used iSCSI block devices and cannot re-establish connection to the storage LUNs prior presented by the NAS device.  There is no viable resolution to this change by Synology to save or recover the data, and Unitrends will be unable to reformat or re-use that volume.  

To continue to use the Synology device as a Unitrends UB backup storage target, the following is required:

  • Delete the prior block device from Synology
  • Configure a new device either as iSCSI or NFS or SMB3 and connect that storage to your hypervisor as a datastore
  • Deploy a new UB image in your hypervisor
  • Connect a virtual disk in your hypervisor to the UB located in the Synology datastore
  • Perform appliance DR (if able) from prior cold copy or hot copy targets
    • for DR from Unitrends Cloud targets, contact Unitrends Support for assistance
To continue to leverage your synology NAS as a cold copy target:
  • reboot your UB to ensure there are no lingering stale iSCSI connections to the old storage device
  • In the unitrends UI, remove the prior cold copy target 
  • Configure an NFS volume (recommended) or CIFS volume in your Synology
  • Configure the created volume as a Cold Copy network share target in the Unitrends UI. 


Synology Software version 6.2 Discontinues Support for Block-Level iSCSI connections for several, NAS models. At this time Unitrends does not have a complete listing of impacted models, but has confirmed from Synology Support that at least the following systems are impacted.  This information can be found in the official Synology Release Notes under the "What's New" section, subsection 2 "iSCSI Manager" found in the links below:

This was an explicit decision made by Synology Product Management and Development to revolk this feature from your device.  

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