"Error obtaining distributed lock" / "Unable to obtain lock for user" / "Retry Count Exceeded"

When CloudM Migrate is migrating to Google Drive, it uses a distributed file locking mechanism to ensure single process access to the files/folders during their migration. This mechanism is required as many users can have access to the same file and we need to make sure that the migration of a file is only performed once.  The distributed locking mechanism is performed by temporarily creating/deleting special files in a Drive Users account.  The existence of these files indicates a lock on a specific file they reference.

By default, it will attempt to use any destination user to perform the lock and, therefore, all users on the destination will need to be active (not suspended) and have Drive enabled for the duration of the migration. No user should be renamed or deleted for the duration of the migration, either, because we list the destination users at the beginning of each migration. If any single OU has Drive disabled, or any single user is suspended, it's most likely that you'll encounter the error "Error obtaining distributed lock". To avoid this, you need to ensure that all destination users are active and have Drive enabled.

The alternative to this is the setting 'Drive Locks From Listed Users Only' (page 2/Advanced settings of your configuration), which allows for CloudM Migrate to only attempt to perform the locks using listed users (in your Users List on page 3 of your configuration) only. For this purpose, all listed destination users must be active and have Drive enabled.

One rare occurrence is when Drive items have a very large number of individual permissions applied (as opposed to permissions lists which are condensed into individual and group permissions). If this is the case, it's likely that multiple attempts will be made to lock items using a user who is already locking another item. In this case, the max retry count (by default, it's 20) may be reached and the user migration will fail with "Unable to obtain lock for user" and "Retry Count Exceeded". For this, there is a setting which allows you to increase the 'Lock Retry Count' (on page 2/Advanced settings of your configuration). 

Please note, however, as we cannot possibly quantify the number of individual permissions involved, we cannot quantify what the value of this setting should be, so we suggest, at first, doubling and retrying, and if that results in failure again, then double it again and so on. It will, eventually, rectify the issue.