So, we have a server that we use iSCSI for the DB files. I was concerned about the performance so we ran some tests. Running a backup from the iSCSI drive to the local drive ran at about 19MB/s. Pretty bad. We ran the same test on our SAN and got 200MB/s. So I asked the server guys and the network guys if they had any ideas. They ended up implementing "jumbo frames", taking the settings from the default 1500 MTU size to 9000. Unfortunately they also changed the subnet, and some VLAN settings, and the microcode on the switches, against my arguments.
Anyway, now when I run the test it goes at 2MB/s. So now it's 10x slower than it was before!
The reason I'm posting here, other than to whine of course, is to see if anyone has any recommendations on what might need to change in SQL Server itself, in case that's the problem. I only have a vague understanding of networking, so was wondering if we need to switch the configurations in SQL Server to be utilizing larger packets now that the jumbo frames are in place.
Thanks for your help,