Using nearline storage: Difference between revisions

Using nearline storage (view source)

Revision as of 20:47, 11 July 2022

455 bytes added , 2 years ago

More details about diskusage_report --nearline

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-Before starting [[Transferring_data|any transfer]] using [[Globus]] or another tool, make sure all the data are already back on disk. Otherwise, transfers will constantly hang and probably overload the tape storage system.
+While [[Transferring_data|transferring data]] with [[Globus]] or any other tool, the data that was on tape gets automatically restored on disk upon reading it. Since tape access is relatively slow, each file restoration can hang the transfer for a few seconds to a few minutes. Therefore, users should expect longer transfer times from Nearline.
+For an overview of the state of all files saved on Nearline, '''some clusters''' support the following command:
+{{Command|diskusage_report --nearline --per_user --all_users}}
+The different <code>Location</code>'s are:
+* <code>On disk and tape</code>: this data is available on disk.
+* <code>Modified, will be archived again</code>: the newest version of the data is on disk.
+* <code>Archiving in progress</code>: the data is being copied or moved to tape.
+* <code>On tape</code>: the data is only on tape.
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-You can determine whether or not a given file has been moved to tape or is still on disk using the <tt>lfs hsm_state</tt> command.  "hsm" stands for "hierarchical storage manager".
+Then, you can determine whether or not a given file has been moved to tape or is still on disk using the <tt>lfs hsm_state</tt> command.  "hsm" stands for "hierarchical storage manager".
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 You can explicitly force a file to be recalled from tape without actually reading it with the command <code>lfs hsm_restore <FILE></code>.
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-Note that as of October 2020, the output of the command <code>diskusage_report</code>, also known as <code>quota</code>, does not report on /nearline space consumption.
 == Cluster-specific information == <!--T:6-->