Size data buffers value

[Pinku]

Hello All,

I was searching for size data buffer values and came across the below forum discussion:

http://www.symantec.com/connect/forums/how-data-buffer-size-and-buffer-number-effect-netbackup-backup-and-restore-performance

I wanted to know, do these values have any limitation respective to hardware i.e. tape library or tape drive. My backups are written on data domain SIZE_DATA_BUFFERS_DISK value set to 1047552, however when I am trying to duplicate this image to tape with SIZE_DATA_BUFFERS value set to 1047522. It fails with below error:

12/9/2013 1:04:05 PM - Error bptm(pid=724) The tape device at index -1
has a maximum block size of 524288 bytes, a buffer size of 1047552
cannot be used
12/9/2013 1:04:05 PM - Warning bptm(pid=724) media id 0805L6 load
operation reported an error
 

When I keep the SIZE_DATA_BUFFERS value set to 262144, it fails:

12/9/2013 8:58:54 AM - started process bptm (2332)
12/9/2013 8:58:55 AM - Error bptm(pid=2332) Attempting to duplicate NDMP backup with block size 1047552, However max configured block size is 262144.
12/9/2013 8:58:55 AM - Error bptm(pid=2332) The configured block size must either be >= 1047552, or evenly divisible into 1047552. Modify the appropriate SIZE_DATA_BUFFERS parameter.
12/9/2013 8:58:55 AM - Info bptm(pid=2332) EXITING with status 20 <----------
12/9/2013 8:58:55 AM - Error bpduplicate(pid=13864) write host crppms1vmmprd22.nychhc.org: invalid command parameter (20)
12/9/2013 8:58:55 AM - Error bpduplicate(pid=13864) Duplicate of backupid 172.24.34.55_1386417604 failed, invalid command parameter (20). 

Environment: Master/Media: Windows Server 2008 R2, NB - 7.5.0.5

[RamNagalla]

the problem is with your SIZE_DATA_BUFFERS_DISK value.

1047522/262144   = 3.9959 

is not  divisible.. and the and it should be divisible.. if not ther is a possbiliy of data leak... 

the discussion that you have provided have the value 1048576, which is divisible.

1048576/262144   = 4

pleae try to change the SIZE_DATA_BUFFERS_DISK vaule to 1048576

read below article to understnad about the buffers

http://www.mass.dk/netbackup/guides/49-netbackup-buffer-tuning.html

[Pinku]

I think, they should be divisible by 1024 and it has also mentioned in the job failure that the tape index has maximum block of 524288 i.e. 512KB. The reason I didn't use 1048576, because if I keep this value for Disk buffers, backups fails to data domain, so we have kept it as 1048576-1024=1047522. I also want to add its NDMP type backup.