Hi Alain,
It is not currently possible to change the 16k blksize on Hsm migration or 
backup tapes.
Regards
             Dave

***********************************************************************************************
 Hello,  
 
Thank's for your update, but do you an idea to change the value, just because 
I'm sure that the default value is not use 
Regards 
  
Alain 
 
-----Message d'origine----- 
De : IBM Mainframe Discussion List [mailto:[email protected]] De la part 
de David Devine 
Envoyé : jeudi 7 février 2013 12:24 
À : [email protected] 
Objet : Re: blksize for ML2 migrated dataset via HSM 
 
Hello, 
The Datamover parameter of DSS or HSM only applies to Control dataset backups 
and is not for general usage. 
 
Hsm has used a 16k blocksize for backup and migration tapes since inception, 
possibly because originally it was a good performance match for the specs of 
existing 3420 "polo" tape drives and the upcoming 3480 "cartridge" tape drives. 
(People who read the announcment specs in the early 80's feel free to dive in!) 
 
Well overdue for an update. 
 
Dumps however are straight dfdss and depending on what Z/os release you are on, 
the blksize will be the default of 256K (Zos 1.12 up) or 64K (Zos 1.11 down) or 
even 32k if you use the patch!   
    
While we are at it, an ML3 level for long term archive datasets (greater than 5 
years say) would be good to split them out from all the other stuff on ML2. 
 
regards, 
             Dave 
 
 
***********************************************************************************************
  Hello, I observed a blksize of 16k for all ml2 migrated dataset (seen on the 
CA1 product). I use DSS as datamover and i'm wondering about the size 
concerning the blksize. Why dss don't use 256k since zos 1.12 ? 
Everybody will have an answer. thank's      
 
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