> 1. I am told NDMP level backups/incremental are block level backups. Is this 
> true ? If so, how is this different from block level incremental(BLI) backups 
> ?


What do you mean by block level backups?  Are you are using Netbackup 
terminology in a NetWorker setting?

The Filer or NAS is the one that uses its native backup program to backup the 
data.  Just like in a Unix environment, because it is like a flavor of Unix, 
you specify the backup command you want to use when you configure the NetWorker 
client's backup command.  For example:

   nsrndmp_save -T dump
   nsrndmp_save -T tar



> 3. Why are NDMP incrementals significantly large in size compared to 
> conventional incrementals ?


Just like a UNIX dump or tar, it only can perform a full or differential (1-9) 
level backups.  It cannot perform incrementals because it does not know what 
incrementals are, so if you use incremental, it will default to full backup.  
This is why incremental backups looks like it backs up everything, because it 
does.

You can simulate incremental backups by using backup levels.  For example, 
Sunday to Saturday backup level could be: full, 1, 2, 3, 4, 5, 6.  This would 
effectively backup only changes between each day, except for Sunday which is a 
full backup.



> 2. When a level backup is initiated, what is the process. Will the filer walk 
> the filesystem to identify the changed files and read those files or will it 
> identify the changed blocks and move the blocks to the target



The NetWorker server contacts the filer by using ndmp protocols.  The filer has 
an ndmpd process running and listening for requests on specific tcp port.  When 
you run the nsrndmp_save, NetWorker connects to that ndmpd and passes the 
backup type (dump or tar) plus any application information that is configured 
in the NetWorker client configuration.

I now think you are referring to raw partition backups when you specify blocks 
level backups, such as using rawasm.  I dont know if tar or dump does this.  
Maybe there is another command that can invoked when doing ndmp backups?



> 4. Symantec NBU guide talks of Netbackup supporting incremental NDMPs. Pls 
> comment


Never used it, so I don't have comment.

+----------------------------------------------------------------------
|This was sent by wl905 AT yahoo DOT ca via Backup Central.
|Forward SPAM to abuse AT backupcentral DOT com.
+----------------------------------------------------------------------

To sign off this list, send email to listserv AT listserv.temple DOT edu and 
type "signoff networker" in the body of the email. Please write to 
networker-request AT listserv.temple DOT edu if you have any problems with this 
list. You can access the archives at 
http://listserv.temple.edu/archives/networker.html or
via RSS at http://listserv.temple.edu/cgi-bin/wa?RSS&L=NETWORKER