Hello,

Has anybody of you tried to tune RMAN BLKSIZE parameter to dovetail it with NetBackup's SIZE_DATA_BUFFERS?

The point is we've got a number of Solaris-based SAN media servers with multiterabyte Oracle databases.
On each of these NetBackup servres we have SIZE_DATA_BUFFERS set to 1Mb (1048576) and iostat clearly shows that data is sent to tape drives using 1Mb block size.

In order to boost Oracle backup performance we tryed to tune BLKSIZE parameter in Oracle backup script.
Oracle tuning guide claims that BLKSIZE should be set slightly less than SIZE_DATA_BUFFERS, so we 
modified CONFIGURE CHANNEL  command in the following way:

  CONFIGURE CHANNEL DEVICE TYPE 'SBT_TAPE' PARMS "BLKSIZE=1048400"

Unfortunatelt it turned out that Oracle reads data from disk using 512k blocks. iostat vividly shows that.

I'd like to listen to your thoghts regarding this issue.