Silo Migration - Frequently Asked Questions

Question 1

Question: What file systems are being affected by this change?

Answer: Files located in $ARCHIVE and /projects reside on file systems involved in this migration. Files residing in $HOME, $CENTER and /center/d will not be affected by this change.

Question 2

Question: What can I do to assist with the tape migration?

Answer: There are several things you can do to assist with this migration:

  1. If you know that you need to use particular data in the next 3 months, please issue a batch_stage on that data. This will ensure the data is brought online and will help us determine the order of data migration.
  2. Review any data you have in $ARCHIVE and /projects and remove any data that is no longer needed.
  3. Please be patient if you experience longer than normal stages after the migration has begun.
  4. If you have data residing in $CENTER which you plan to copy to $ARCHIVE or /projects, please start copying the data to the appropriate file system as soon as possible.

Question 3

Question: What is ARSC doing to reduce the impact of the tape migration?

Answer:We are doing several things:

  1. We have been carefully reviewing data access patterns to attempt to bring recently used data online during the migration.
  2. We are increasing the size of the online $ARCHIVE disk pool to a little over 300TB during this migration.
  3. We are increasing the maximum file size for files saved to the "Copy 1" disk pool. This will allow more small files to be quickly brought back online without access a tape drive.

Question 4

Question: I have a significant number of older files which I need to use but wasn't able to stage prior to 1/28. What is the best way to bring these files online?

Answer: The "batch_stage" command is generally the best way to stage files. If you find that a significant number of files have not yet been staged, contact the ARSC Help Desk to request the particular files and/or directories be expedited, however running batch_stage prior to 1/28 is the best solution.

Question 5

Question: When I ran the "batch_stage" command it indicated some of my files were "out of library". What does this mean?

bigdipper !% batch_stage ncl-5.2.1.gnu.tar.gz 
Staging Files...
1    |1    : stage  ncl-5.2.1.gnu.tar.gz [out of library]

Tape Migration Summary
--------------------------------------
Tapes to Migrate:                    1
Files to Migrate:                    1

WARNING: Some files in this batch_stage request need to be migrated
from old tape media and may require extended wait periods.  Files on
old media are denoted with [out of library].

Answer: The "out of library" message is an indication that the files in question have not been migrated to the new tape model yet. Files flagged as "out of library" could take much longer to stage.

Question 6

Question: A few hours ago I ran the "batch_stage" request and some files were listed as "out of library". How can I check to see if the files are online now?

Answer: The "batch_stage" command can safely be rerun on a set of files. Only files that are currently offline will be listed in the "batch_stage" output. When "batch_stage" lists no offline files, the initial stage request is complete.

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