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Version: current [25.0.x]

NAS

Working with files and folders in your NAS​

If your Dremio cluster is connected to your NAS, you can query folders and files stored in this data source.

All nodes in your Dremio cluster should be able to connect to your NAS.

Dremio Configuration​

General​

![](/images/nas-general.png) !
  • Mount Path -- Path on the filesystem to use as the root for the source. Needs to be accessible on all nodes.

Advanced Options​

![](/images/nas-adv-options.png) !
  • Enable exports into the source (CTAS and DROP).

Reflection Refresh​

![](/images/hdfs-refresh-policy.png) !
  • Never refresh -- Specifies how often to refresh based on hours, days, weeks, or never.
  • Never expire -- Specifies how often to expire based on hours, days, weeks, or never.

Metadata​

![](/images/nas-metadataD.png) !

Dataset Handling​

  • Remove dataset definitions if underlying data is unavailable (Default).
    If this box is not checked and the underlying files under a folder are removed or the folder/source is not accessible, Dremio does not remove the dataset definitions. This option is useful in cases when files are temporarily deleted and put back in place with new sets of files.
  • Automatically format files into tables when users issue queries. If this box is checked and a query runs against the un-promoted table/folder, Dremio automatically promotes using default options. If you have CSV files, especially with non-default options, it might be useful to not check this box.

Metadata Refresh​

  • Dataset Details -- The metadata that Dremio needs for query planning such as information needed for fields, types, shards, statistics, and locality.
    • Fetch mode -- Specify either Only Queried Datasets, All Datasets, or As Needed. Default: Only Queried Datasets
      • Only Queried Datasets -- Dremio updates details for previously queried objects in a source.
        This mode increases query performance because less work is needed at query time for these datasets.
      • All Datasets -- Dremio updates details for all datasets in a source. This mode increases query performance because less work is needed at query time.
      • As Needed -- Dremio updates details for a dataset at query time. This mode minimized metadata queries on a source when not used, but might lead to longer planning times.
    • Fetch every -- Specify fetch time based on minutes, hours, days, or weeks. Default: 1 hour
    • Expire after -- Specify expiration time based on minutes, hours, days, or weeks. Default: 3 hours

Sharing​

![](/images/hdfs-sharing.png) !

You can specify which users can edit. Options include:

  • All users can edit.
  • Specific users can edit.