On Thu, Sep 15, 2005 at 04:13:56PM -0400, Bernard_Wu AT NCCI DOT COM wrote:
> 
> Hi Amanda gurus,
> This is my current environment:
> 4 Linux LPARS running on an IBM z890 mainframe.
> Our Linux LPARS currently do not have any tape drives attached to it.
> Once a week, we bring Linux down to run level 2 and then use the
> mainframe's backup mechanism ( DFDSS ) to do full volume backups of all the
> disk drives.
> I would like to complement the weekly backups with incremental backups
> using Amanda.
> 
> The intent is to do incremental backups to disk.  This disk will be NFS
> mounted to the mainframe.  Once the mainframe receives the backed up
> file(s), its own  Hierarchical Storage Management kicks in and takes care
> of staging it till it finally goes to tape.

Be aware that there are two types of incrementals in common use:

- A base image is created and the first incremental is the
  changes from that base.  Subsequent incrementals are just
  the changes from the last incremental.
- A base image is created and refered to as a level 0 backup.
  The first incremental, a level 1, is the changes since the
  base, level 0.  So far the same.  But subsequent incrementals
  may be level 2 (and higher), changes from the level 1 (like above)
  or another level 1, 'all' changes from the level 0.

Amanda uses the levels scheme and as it may stay at the same level
for several days, each incremental gets larger and larger.  Amanda
also repeats the level 0 periodically.  It sounds like you don't
expect your local backup to ever have done a level 0, depending on
the mainframe for that.  That would be tough to do with amanda.

> 
> Here are my questions.
> 
> 1.  Since we do not have any tapes, can I use only the "holding disk" to
> hold the backups and then do I comment out these tape parameters :
>       - runtapes 1
>             - tapedev  "/dev/nst0"
>             - rawtapedev "/dev/nst0"

A better choice would be to investigate "virtual tapes"
for your "virtual machines" :)

Amanda has something called a "file:driver" that uses
disk space as if it were a tape changer.  Check the docs.
The holding disk is still used to collect the dumps which
are then "taped" to the vtapes.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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