The VIRTUALMOUNTPOINT is still around because it effectively
separates a large filesystem into smaller, more manageable
chunks. Based on my observations of the way the server works, and
some talks with various developers, I believe that a node's
backup objects are keyed off of the filespace name--perhaps even
broken into separate tables.

This can effectively reduce your workload on retrieves/restores,
and can also allow you to multiplex a restore operation when a
single physical filesystem is broken into two or more "VIRTUAL"
filesystems. Thus, even though it is now possible to do an
incremental backup of a subset of a filesystem w/o the
VIRTUALMOUNTPOINT option, the option does still provide
flexibility to some customers.

We take advantage of the VIRTUALMOUNTPOINT parameter to back up
our user's home directories under their automounted location
(/usr/home/tlaporte, e.g.) rather than via their physical
location. This way, when a user's home moves from one machine to
another--which is a common occurence in our environment, given
that home directories are always on option drives, and user's
equipment needs are constantly shifting--we can physically
relocate the home directory, do an EXPORT NODE of the filesystem
from the original location, and IMPORT NODE to the new system,
and avoid the full backup that would otherwise occur.

As to the second question, I haven't specifically observed the
behavior, but I do believe that "COLLOCATION FILE" used in
conjunction with "VIRTUALMOUNTPOINT"s would exhibit the behavior
that you describe, i.e. a unique set of tapes for each
VIRTUALMOUNTPOINT.

 -- Tom

Thomas A. La Porte
DreamWorks Feature Animation
tlaporte AT anim.dreamworks DOT com

On Wed, 24 Feb 1999, Dwight Cook wrote:

>     Why do they bother to keep the VIRTUALMOUNTPOINT then ?
>
>     Has anyone tried "COLLOCATION FILE" in conjunction with
>     "VIRTUALMOUNTPOINT blah" to see if a virtual mount point is forced to
>     a unique set of tapes on the adsm server ? ? ?
>
>     ARGH ! I'm getting slow in my old age (sigh!)
>
>     later,
>           Dwight
>
>
>
>
>______________________________ Reply Separator 
>_________________________________
>Subject: Re: Selective Backup Objects
>Author:  HiltonT (HiltonT AT TCE DOT COM) at unix,mime
>Date:    2/24/99 12:00 PM
>
>
>Not true.  I thought it was that incrementals specified file systems, and
>selective backups specified directories, but I guess I was wrong or it
>changed with version 3.  I looked it up in the manual and did a test and
>discovered that they both work on the file level.  The only thing you have
>to worry about is with the selective backup and -su=y.  If the subdirectory
>is a mounted file system, it will not backup that file system.  I have a
>file system called /syslogs and both "dsmc s /syslogs/adsm/*" and "dsmc i
>/syslogs/adsm/*" work.  Here's some excerpts from the Unix Backup/Archive
>Client manual on incremental & selective backup:
>
>Incremental backup -- Backs up all files and directories in the specified
>file system or directory that meets certain criteria.
>
>The selective command backs up specific files. Use wildcards to back up more
>than one file at a time. If you back up a directory, you can use the
>subdir=yes option to include all the subdirectories under that directory in
>the backup. For example, to back up the /home/monnett/proj directory and its
>subdirectories, enter:
>      dsmc selective /home/monnett/proj/ -subdir=yes
>
>> -----Original Message-----
>> From: Dwight Cook [SMTP:decook AT AMOCO DOT COM]
>> Sent: Wednesday, February 24, 1999 11:46 AM
>> To:   ADSM-L AT VM.MARIST DOT EDU
>> Subject:      Re: Selective Backup Objects
>>
>>      Archives work off of file specifications
>>
>>      Backups work off of fileSYSTEM specifications
>>
>>      with the incremental or selective command you must use either a true
>>      file system name OR the object of a VIRTUALMOUNTPOINT option
>>
>>      So something like
>>         selective -subdir=yes /home/
>>
>>
>> ______________________________ Reply Separator
>> _________________________________
>> Subject: Selective Backup Objects
>> Author:  Denver.UNIX.Support (Denver_UNIX_Support AT JDEDWARDS DOT COM) at
>> unix,mime
>> Date:    2/24/99 9:37 AM
>>
>>
>> Hi Everyone,
>>
>> What is the correct "objects" syntax to selectively backup a directory on
>> a
>> UNIX system, i.e., /press/ora_export/...?
>> Thanks in advance for your input.
>>
>> Daniel Penrose
>> J.D. Edwards & Company
>> UNIX  Systems Administration
>> One Technology Way
>> Denver, CO. 80237
>> (303)334-4747 DIRECT
>> (303)334-1290 FAX
>> daniel_penrose AT jdedwards DOT com
>