Hi Eric,
If you look at HP's SDLT 600, that has a maximum transfer rate of 72MB/s compressed, and 36MB/s uncompressed.
Your backup rates will differ depending on what type of data you're currently backing up, but at 874MB/M, you're only running around 14.5MB/s which is slow.
From my side I increase the Buffer Size to 1MB, and leave the rest as-is. This sees a performance increase, but it's not a miracle cure.
Try that and see what it does. I wouldn't mess with the block size, as you're going to get a warning that you risk corrupting your data on restore.
Look at the firmware revision, and update that. It sometimes comes with added improvements to speed amongst others.
Your data will also affect the speed of backups. Lots of little files means your tape drive is not spinning at a constant speed, so it will basically spin up, for 1 file, slow down, spin up for the next file etc.
Download the latest Symantec drivers and apply those as well if need be.
SDLT is also a slower technology that other newer forms of LTO, and I am not sure what other people are getting speed-wise on their SDLTs, so I cannot comment.
Let us know how it goes.
