Near-line Archive (NLA)

What is the NLA

The Near-Line Archive (NLA) is where data are stored when they cannot be kept on disk for the CEDA archive. The main users for this system are Sentinel datasets which are too large to all be kept on disk, other datasets which are not used frequently have been added as well. 

When to use it

If the data isn't frequently used and large in size is the best time to use the NLA system. This is usually a decision made between data scientists and Sam. 

How to use it

To move data to tape you can move over whole filesets which have been created in the cedaarchiveapp (https://cedaarchiveapp.ceda.ac.uk/admin/cedaarchiveapp/fileset/). You have to ensure that the fileset that you want to be moved to the NLA is ticked for 'Sd backup' as well as 'primary on tape'. Only files over a certain size (find file size) will be moved from disk to tape. Once a fileset has been ticked for tape it will be verified that the file on disk is the same as the file on tape before the NLA system will remove it from disk to only be on tape. There are some exceptions such as Sentinel 1 products which are not fully verified, these just make sure there is a record of the file on tape before removing it.

The admin interface for the NLA system can be found here: https://nla.ceda.ac.uk/admin/

Guidance for Users

The users guide is at https://help.ceda.ac.uk/article/265-nla

This will run through how you can pull data back from tape. Currently, only JASMIN users can pull data back from tape. 

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