LTO4 tapes not fatser than LTO2

[JPodgorny]

Did you ever get resolution on this issue? I'm experiencing a similar problem. We are backing up a 2.1 TB SAP database using 4 LTO2 drives. We recently got a new library that has LTO4 drives so I am migrating the backups over to this. We're getting about 50 MB/s on each LTO2 drive currently. I presumed that I would be able to use 2 drives instead of the 4 drives and get the backup accomplished at the same rate. But when I start a backup with 2 drives, they are only getting 50 MB/s each still. I change the policy to allow it to use 4 drives and they get 50 MB/s on all 4 of them. Obviously I'm not killing the source volume with the 2 drives, because it was doing 50 MB/s on 4 drives before, and can do 50 MB/s on 4 drives now. It is using 2 separate 2GB fiber cards, one for the tape and one for the disk. I shouldn't have any problems pushing 2 LTO4 drives at 100 MB/s each, at very least, according to the specs it might even be possible for me to get the full 200 MB/s I was getting before on a single drive. So why would it not be happening?

I'm going to update my stape drivers tomorrow, but I did patch this thing back in January. What else could it possibly be?

[JPodgorny]

Found a resolution on my issue. We're using Veritas Netbackup as our backup software. There were some shared memory buffer settings that needed to be bumped up. I'm now getting 160 MB/s and am going to try bumping these further to see if I can get even more.