Tape copies and Deployment with multiple drives per server

General Discussion
1

Hello,

  1. Maybe this is a unique issue but is it possible to enforce a tape copy to a different tape technology (e.g primary copy on LTO-9 and duplicate on JE?)

  2. Maybe @george_patargias or anyone else running a similar setup can chip in here on their experience with running multiple tape drives per tape server. How has the experience been and what are the benefits/drawbacks if any?

Thanks a lot,
Mwai

2

Hello Mwai,

  1. At CERN we organize different types of media into separate tape pools. When we set archive routes we point tape copies to the tape pools of different types.

E.g.:

cta-admin archiveroute add --storageclass <name> --copynb 1 --tapepool r_name_1
cta-admin archiveroute add --storageclass <name> --copynb 2 --tapepool r_name_2

Cheers,
Vova

1 Like
3

Hi Mwai,

Not sure of the status now, but at PIC with our current tape system we have multiple drives per tapeserver and, as far as I remember, CTA only allows or at least only allowed when we started some months ago, to use one drive per tapeserver.

This would be a stopper for us in terms of moving into production since we have limited space for tapeservers in the datacenter.

Cheers,

Jordi

1 Like
4

Hello Mwai,

At RAL we run our CTA tape servers with either 2 or 4 drives per server. We have no problems running servers with this.
Like CERN we have a mix of tape pools that the archive rules move the data to. We will be running CTA with files going to two copies on different media types for some user groups, as we do with Castor.
The only things to note for having multiple drives/server are -

  1. if you need to restart the tape daemon or re-boot the server, then you will take multiple drives out of service, even if one is doing useful work.
  2. in our set-up with the Spectra libraries means that you can only have drives of the same media type on a server due to the way rmcd works.
  3. if labeling tapes, you need to comment the TPCONFIG file so only one drive is not commented out, the “cta-tape-label” program does not work if there are multiple drives defined. Once the labeling is done, just un-comment the drives in TPCONFIG. No restart of the tape daemon is required.

Let me know if you have any questions

Tim

2 Likes
5

Thank you all for the responses.

@vyurchen ah yes this is it!

@jcasals we’ve always tested CTA w/ a multiple drives/per node set up so it should be possible for you.

@gtf87 thanks for the heads up. Just as a remark, it’s now possible to label tapes by specifying the drive number. This was fixed in 205. You had actually requested for this feature :slight_smile:

Mwai

6

@Mwai Don’t think we have upgraded to this level yet, but look forward to the fix when we do :slight_smile: