my understanding...

you can have up to 10 copies, but can only do 4 Inline Tape Copies at a time.

yes, vault is required for Inline Tape Copy.  you can use bpduplicate without
vault, just like with 3.x, but ITC requires vault.


- Scott



                                                                                
                                                   
                    "Fabbro, Andrew P"                                          
                                                   
                    <Fabbro.Andrew AT cnf DOT com>              To:     
veritas-bu AT mailman.eng.auburn DOT edu                                 
                    Sent by:                             cc:                    
                                                   
                    veritas-bu-admin AT mailman DOT eng.        Subject:     
[Veritas-bu] NB 4.5 and Inline Copies?                       
                    auburn.edu                                                  
                                                   
                                                                                
                                                   
                                                                                
                                                   
                    07/09/2002 12:27 AM                                         
                                                   
                                                                                
                                                   
                                                                                
                                                   




My understanding from NB notes I've read is that 4.5 supports in-line backup
copies.  e.g., you backup a client and write the backup to two tapes at the
same time.  The NB release notes say you can do up to 9 copies at the same
time.

Putting additional drives needed, etc. aside for a moment, it seems like it
could be a good way to make offsite/disaster recovery backups without the
hassle of either duplicating tapes (which doesn't scale well) or running
another full backup
for offsite/DR purposes.  I assume one could use Pool A for one copy and Pool
B for another and send Pool B offsite.

Some questions:

- Has anyone used inline copying?  How well does it work?

- In NB 3.4.x, to use a duplicate of a tape, you need to flip it to the
primary copy.  It's easy enough to script - does NB 4.5 work the same way?

- What about shared memory usage?  The calculation for NB 3.4 is number of
data buffers x size of data buffers x number of drives x MPX per drive.  For a
box driving DLT (64512 data buffer size recommended, maybe 64 data buffers),
it's not a major factor - usually not over 128Mb (say, 8 drives at 4 MPX
each).  With more recent technologies, you want fatter buffers, more buffers,
and more MPX - easily 512Mb of shared memory, maybe more.  But I can't imagine
all of that is just to drive the tape - some of it is network buffering,
right?  So if I need X kilobytes of shared memory for a tape drive, do I need
X times 2 for two drives doing the same backup in an in-line backup?  Or is it
more like X times 1.5  (or whatever)?

Thanks,


-drew
 fabbro.andrew AT cnf DOT com