What does partialtapesnumber mean in tapepool?

Site Administrators
1

Hi there,
We are testing CTA now, confused by some options like tape pool option partialtapesnumber which may be lack of explanation. Are there any more detailed docs about these options?

2

Hello Yujiang Bi,

a tape pool is a collection of tapes for a particular experiment.

When experiments write data to a tape pool, the tapes became full.

However, in order to guarantee that there is some space where data can be written, there is a concept of partial tapes = tapes that are not FULL.

So, if a tape pool is configured to have 1 partial tape, we have another script that looks at that number and will keep adding at least 1 non-full tape as the data is written to that pool.

Did I answer your question?

Let me know if you need more help. Best regards,

Vladimir Bahyl

3

Hi, Vladimir. Thanks for the reply, it does make this option clear and saves me a lot of time.

4

To clarify CERN tape management, we have free empty tapes in so called supply tape pools.

Then, every user tape pool with user data has a value of partial tapes set to (for example) 1 and the supply column specifies from which tape pool new tapes should be taken.

For example:

userpool1 partialtapes=1 supply=supply_LTO8

This means that if userpool1 needs more tapes, the other script (I can share it with you) will then move 1 free LTO8 tape from tape pool supply_LTO8 to the tape pool userpool1.

Best regards,

Vladimir

5

Oh, I had thought supply means manufacturer, and I misunderstood this option apparently.
We have little knowledge about CTA and maintenance, so it will be a great help to us if you share the script with us.

6

Hello Yujiang Bi,

please send me your e-mail and I will send you the script.

Vladimir Bahyl

7

My email is biyujiang@ihep.ac.cn. Thanks.

8

Are tape pools for each VO or each Storage Class? Assuming we have 30 VOs, can we have 1 tape pool for all VOs and Storage Classes? As an operator, how can we automatically add supply tapes to a tape pool when the VO decides to write new data?

9

nononononononono8899 (Is this your real name? Please some respect here … thank you)

Tape pools are completely orthogonal / independent from VOs or Storage Classes, You can have one tape pool for 30 VOs and 30 tape pools for 30 VOs (each VO has one dedicated tape pool).

What counts are the archive routes which storage class is rounted into which tape pool. That is what is important.

As for assigning free tapes to the user tape pools, this is not part of the core CTA software as this is considered tape operations. We of course have a script to do that according to specific CERN rules but the idea is that each site has different rules so I am not sure how helpful our script would be to you.

Best regards,

Vladimir Bahyl

10

Thanks for the information. Do the scripts use CTA commands to move tapes between a free pool and a VO pool? Or are they library-specific commands? Are these scripts available for public viewing? As an operator, I want to learn as much as possible about CTA operations.

Thanks,

Jeff Derbyshire

11

For a new question, please start a new thread with a new topic instead of resurrecting an old thread, thanks. I am closing this topic.