Windows filesystem has a file attribute for offline files. If this attribute is set, the file appears in File Explorer with a grey X icon (in Windows 10 or earlier) or an archive box (in Windows 11). For example, for files in a OneDrive folder in which a file's content is in the cloud, its offline attribute is set and appears as below.

Grey X icon in Windows 10 (Archive box icon in Windows 11)

The purpose of the offline flag is to save space on the local storage. Accessing these files will take a longer time, because the file content must be fetched from an offline location, most likely the cloud. Recent Windows utilizes this flag to disable creating thumbnails, indexing for faster search, etc. However, some applications may ignore the offline flag and read file contents as soon as a folder is opened in File Explorer. This behavior results in the file contents being fetched and thus conflicts with the use of the offline flag.

If the offline location (such as cloud) is not accessible, you cannot open these files. If you want to watch a movie on a plane without in-flight WIFI, make sure the movies are not offlined. Typically, opening an offline file will trigger the copying of the file content from the offline location to the local file system.

How to solve?

It is depending on your system. If you see X on the OneDrive/Dropbox folder, you have sync issue, such as account reached to limit capacity. In following sections, we will explain how to analyze further using Morro CacheDrive.

Why I cannot access files with a grey X on a CacheDrive?

It is possible that you have run out of local storage space and that there is no room for the contents of the offline files when accessed. Although the Morro Global File System has a limitless capacity, the cache on the CacheDrive is limited. 

For the network share hosted by the Morro Data CacheDrive, files that are not in the local cache will have a grey X (or archive box in Windows 11) as they appear in File Explorer.  Normally, the CacheDrive will automatically download the file from the cloud when the file is accessed and the grey X will disappear.

However, there may be some instances where the file cannot be downloaded from the cloud and the file contents will not be available.  In some cases, the application may say that the file is corrupted or inaccessible.  Some possible reasons for this are:

  1. Internet access is down.
  2. The cloud storage service (Wasabi, Amazon S3, etc.) may be down.
  3. The cache may be filled with files that cannot be cached out.  This includes files that for some reason could not be uploaded to the cloud.

Reasons #1 and #2 above are generally out of our control.  For #3, check the amount of Writable Cache Space reported in Morro Cloud Manager (MCM):

The cache may be filled with files that cannot be cached out

Writable Cache Space is the sum of Unused Cache Space and the space used by files that can be cached out.  If the Writable Cache Space is low, it's very possible that #3 above is the cause of the issue.

How can I make room for cache on a CacheDrive?

Low Writable Cache Space has several causes, two of which are:

  1. Replicate shares that have not been synced.  Since these files have not been uploaded to the cloud, the local versions of these files are the only ones available and cannot be deleted without data loss.  Run a manual or scheduled sync of the replicate share to enable the device to cache-out these files.
  2. Files on the sync exclusion list consuming a lot of space.  This is an unusual condition, but is possible, for example, if large backup files are saved using the .bak extension.  Microsoft recommends using the .bak extension for SQL Server backups, so frequent database backups to the CacheDrive may consume a large amount of storage.  To remedy this situation, change the sync exclusion list to allow the syncing of files with this extension or write the files with a different extension.

    To change the sync exclusion list, see the following article:

    How do I change what type of files to sync to the cloud?