slow back-up SAN

Hi,

Since we have upgrade to BE 15 we experince slow backup of our SAN (Dell MD3000). before the upgrade we had BE 2010 R2 andone in 5 or 6 month we had the same issue and rebooting the server would solve the issue.

But now when run the same job to backup 200 GB data on a SAN it take about 8 hours. I did create a new job to backup the same data and at fitst it start with a really good speed and then it start to come down to 530mbs

on the SAN has nothing being changed and the SAN is connected with ISCSI directly to ha power edge server.

Any idea