IBM i Global

Hello, I want to make a save 21, but I would like to use an asp2 so that the disks can be divided and not affect the performance of the system's asp. Can this be done?

Dear Miguel

Based on my 33-year experience with IBM i, your expressed concern about degraded disk performance at high disk IO workload generated by saving large amount of data at once is valid for the case in which your IBM i server has only spinning disk and contains a small number of units.  But if your server has, say, more than 40 units of spinning disk units, you do not have to be concerned much about this.  Also little concern when you use all SSD units.

If your server has limited number of spinning disk units, you can use a user ASP for an IBM i virtual tape drive by mapping the select IFS path created for the virtual tape drive to a user ASP using what is called User-defined File System (UDFS).   Follow this Technote on how to do this :  Specifying ASP When Using Integrated File System at https://www.ibm.com/support/pages/specifying-asp-when-using-integrated-file-system.   

One last point I want to make here. Since you will use GO SAVE option 21, there will be NO other workload running when you do the save. So, there is no good reason for you to worry about negative performance to the active application workload as there is none.  So, you should not waste your time using a user ASP in this case.  You will worry (and use a user ASP for the virtual tape drive) only when you save a lot of data WHILE some important performance-sensitive application workload is also active during the data save period.   

Hope you understand all this. Let me know if you have more question. 

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Chance favors only the prepared mind.
-- Louis Pasteur
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Satid S.
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Hello Miguel you can do it if you want to separate workloads (maybe your system has two types of external storage) and make others types of concurrents backups.

You only has to create the image catalogue in the parent directory of your iASP or user ASP. I prefer to used the independet asp option.

This is an example.

CRTIMGCLG IMGCLG(VIRTUALTAP) DIR('/IASPVTL/...') TYPE(*TAP) CRTDIR(*YES) 

What problem are you trying to solve?  If it is to perform a full system save in the shortest amount of time in order to minimize downtime I have some items to discuss.  

1:  Assuming you have internal disk drives yes you could put some disks into their own ASP.  Normally these are disks in their own expansion unit with different IOP's etc.

2:  You could upgrade disks to SSD, or better yet, NVMe.  And probably external vs internal.

3:  But I'd argue that instead of Virtual Tape (where you use an image catalog to make your disks look like tape), you need to look at a VTL or Virtual Tape Library.  Let's use my oldest system for example.  I have a Power 9 with internal SSD's.  It has a few lpars of IBM i and one of AIX.  All internal storage is hosted by one lpar of IBM i to the other lpars of IBM i and AIX.  From DSPSYSSTS of one lpar

Auxiliary storage:                   
  System ASP . . . . . . :     5741 G
  % system ASP used  . . :    80.9869

I save to an EMC DD 6900 VTL attached via fiber channel.  A full system save using BRMS started at 2023-12-06-08.38.17 and completed at 2023-12-06-11.57.53.  Basically 4.5TB saved in 3 hours and 19 minutes.

Let's look at the smallest lpar on that system.  Same configuration.  Just a lot less storage.  And most of the storage on the small lpar is IFS and not 'traditional' library stuff.

Auxiliary storage:                   
  System ASP . . . . . . :    447.4 G
  % system ASP used  . . :    44.2586

Save ran from 2023-12-06-09.09.24 to 2023-12-06-09.31.23.  Basically 198GB in 22 minutes.

The last time I used Virtual Tape instead of VTL was a combination of multiple factors:
- We did not have a VTL.
- It was a remote location with no operator to change physical tapes.
And we would FTP the image catalog locally and use DUPMEDBRM to convert to tape.
Now we no longer use physical tapes.  We have no tapes or tape drives other than VTL.