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Retrieval of archived files

Once files are archived in tape, some wait time is to be expected in the retrieval of these files. This is because the tape that holds the file is not always physically attached to the network. When downloading such a file you might get an REPLICA_IS_BEING_STAGED error. This will mean that you cannot download the file at that moment, but in the background the tape is now being fetched!. The hard part here is knowing if the tape is ready or not. We installed a small feature that will show in the metadata if the tape is ready and on which tape the file is downloadable. Once the file is available for downloading it will stay so for 7 days before it has to be retrieved from tape again.

Metadata to track the file availability on tape

Below is the structure that the metadata will get. There is a metadata attribute called WUR_RDM:dataobject:available_to_download which will only exist once the tape retrieval is requested. After 7 days the status will be put back to no to signify that the file is no longer avalable for downloading. If the metadata does not exist that will count as a no.

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- meta_att: WUR_RDM:dataobject:available_to_download
- meta_values: no / requested / yes / not_archived
- meta_units: tape_1 / tape_2

graph LR;
    subgraph WUR_RDM:dataobject:available_to_download
        no --> requested
        requested --> yes
        yes --> no
    end

    not_existing --> requested

Queries to chek tape download availablility.

If you want to see which files are downloadable for you you can run below query: 

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iquest "Current downloadable status of file %s/%s on resource %s : %s" "select COLL_NAME,DATA_NAME, META_DATA_ATTR_UNITS, META_DATA_ATTR_VALUE where META_DATA_ATTR_NAME = 'WUR_RDM:dataobject:available_to_download'"

Future development

Currently we do not have a noticiation system available to use, but if we have then we might be able to notify you about the download status.