If you are using Veritas NetBackup on Solaris 9 with LTO Ultrium-2 tape drives, you will be constantly annoyed by slow tape write performance unless you use blocks of at least 256KB.
To resolve this, the first thing you’ll want to do is increase both the number of buffers and the buffer size on the media manager host:
Create and edit the file: /usr/openv/netbackup/db/config/SIZE_DATA_BUFFERS and add 262144 on the first line.
Create and edit the file: /usr/openv/netbackup/db/config/NUMBER_DATA_BUFFERS and add 16 on the first line.
These numbers with their respective quotes should be the only thing in these two files.
Next, since Solaris still has insanely low limits on its default shared memory subsystem, we have to increase these limits as to not exhaust them with the increased NetBackup Buffer sizes. We do this by editing the /etc/system file and adding the following lines.
It is now necessary to reboot the system for the kernel parameters to become active.
You should now notice a dramatic increase in tape write speed during your backups.