> Hello,
Hello, Dan. 

> I am working with an LTO-4 tape library. It has two drives but I plan to write
> to only one for backups.

> I will backup to disk first, on another SD. Later, I will copy the jobs to the
> tape library on this new SD
> which is on another server. The copy jobs will be spooled to local SSD before
> being written to tape.

> re http://bacula-users.narkive.com/QRkTVfEz/typical-tape-write-performance

> Now what I'm thinking of is streaming multiple concurrent jobs to a single
> drive.

Did you test if it is possible? (I can test for you in a dummy environment if 
you want). I don't remember if it is or if the bellow quote only applies to 
copy jobs... 

"If the Migration control job finds a number of JobIds to migrate (e.g. it is 
asked to migrate one or more Volumes), it will start one new migration backup 
job for each JobId found on the specified Volumes. Please note that Migration 
doesn't scale too well since Migrations are done on a Job by Job basis. This if 
you select a very large volume or a number of volumes for migration, you may 
have a large number of Jobs that start. Because each job must read the same 
Volume, they will run consecutively (not simultaneously)." 
(http://www.bacula.org/5.2.x-manuals/en/main/main/Migration_Copy.html) 

> Sure, downside on restore is interleaving of blocks....

I also remember that I read somewhere that you don't need to concern about that 
when doing copy jobs, but I think it refers to lack of multiplexing quoted 
before. 

> I don't see any downsides to going down this path. I have yet to run any copy
> jobs to the new library,
> but it may be ready this week.

Even without multiplexing, I think you will achieve a hight throughput since 
you are copying sequential data. 
In this case, if you really want to multiplex the copy I think you would have 
to create two different source and destination pools. 

> Comments?

> --
> Dan Langille - BSDCan / PGCon
> d...@langille.org

Regards, 
-- 
======================================================================= 
Heitor Medrado de Faria - LPIC-III | ITIL-F | Bacula Systems Certified 
Administrator II 
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