“The VDI is not available” message is displayed in XenCenter after attempting to start a Virtual Machine (VM). ### Background The additional details of “VDI is not available” error are not displayed. This article describes the error messages, the reasons for VDI not available error message, extract from the storage management code, and records in the /var/log/SMlog along with possible causes and resolution to the issue. The errors have been grouped based on the storage activity occurring at the time they were displayed. #### SR-Scan / VDI load The lvs command is used to get the list of logical volumes (LV). The vhd-util scan is used to verify Virtual Disk Images (VDI) information without activating the logical volumes. If the VHD is corrupted, vhd-util is unable to read this data and it fails. The following error is generated: The VDI is not available Error scanning VDI Errors can be caused by logical volumes being manually removed or by LV metadata corruption. Errors returned in this case are: The VDI is not available LV scan error The VDI is not available LV not found Errors occur if unable to read the VDI and IO retry fails when collecting VDI information: Errors returned in this case are: The VDI is not available not found Failure getting VDI parameters: The VDI is not available VDI unavailable #### VDI-Attach A check for a journal on the VDI occurs and if one exists, we do not attach VDI. This is because an operation is ongoing or was not properly completed. Error returned in this case: The VDI is not available Interrupted operation detected on this VDI, scan SR first to trigger auto-repair. If the Logical Volume (LV) has been removed or missing and the attach is called, the following error is returned: The VDI is not available Could not find Error returned in this case: The VDI is not available VDI unavailable When performing the VDI attach process, a check is performed to determine if the VDI is already attached. Error returned in this case: The VDI is not available VDI already attached RW During VDI Attach for iSCSI LUN, if the device path cannot be found in /dev/disk or /dev/sd* the attach fails. Error returned in this case: The VDI is not available path for VDI not found. During path check, if the path is not found, a failure occurs. Error returned in this case: The VDI is not available unable to query SCSIid #### VDI-detach When performing a detach of LV based VHDs, a deflate operation is performed on snapshots. Error returned in this case: The VDI is not available deflate #### VDI-Resize If the VDI that is being resized is hidden: Error returned in this case: The VDI is not available hidden VDI If the VDI is missing: Error returned in this case: The VDI is not available VDI unavailable #### Snapshot If a LV in the chain has been removed or missing, the following error is generated: The VDI is not available VDI unavailable: If the SR is inaccessible, a failure occurs to get the chain depth. Error in this case: The VDI is not available failed to get VHD depth. If the chain depth is over 30 then a failure occurs. Error in this case: The VDI is not available SnapshotChainTooLong.