[Halld-offline] Fwd: LTO8 tape issue update

[Mark Ito]

 From Bryan, FYI.



-------- Forwarded Message --------
Subject: 	LTO8 tape issue update
Date: 	Tue, 16 Mar 2021 09:51:10 -0400
From: 	Bryan Hess <bhess at jlab.org>
To: 	Mark Ito <marki at jlab.org>, Nathan Baltzell <baltzell at jlab.org>, Ole 
Hansen <ole at jlab.org>, Brad Sawatzky <brads at jlab.org>
CC: 	Graham Heyes <heyes at jlab.org>, Jie Chen <chen at jlab.org>, Andy 
Kowalski <kowalski at jlab.org>



An Update on the LTO8 tape issue:

We've worked with Chris and Ying and they are creating a database 
table/web page for checking the status of the tape recovery. Nothing 
fancy, but something that you can view to see what files are in the 
recovery process. We should have that for you soon.


Some good news:

  * Since the New year we wrote 627TB on 54 LTO8 tapes that were "just
    in case" duplicates to test LTO8. We have now read those tapes back
    with zero errors. This validates the growing consensus that we are
    past the write problem and in the recovery phase.
  * Data center humidity trend data since Jan 1 shows that we are
    staying in the new, tighter specification (>55%). We will be
    watching this closely as we head into summer.
  * With some database work I am getting better bounds on the time
    window when we had the problem, and the drive serial numbers of
    interest. To finish finding the tapes that need recovery, we have
    stopped writing the "just in case" duplicates and we are dedicating
    that tape bandwidth to auditing suspect tapes. As a result, we have
    15 more tapes to go to IBM, and I suspect there will be more.
  * IBM has refined their recovery tools, so we are going to return some
    tapes for a second pass to see if they can recover a greater
    fraction of the files.


Thanks for your patience during this ongoing process. Please let me know 
if you have additional questions.

--Bryan

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