Look at the network traffic with wireshark and also filter out all but what is going to/from the tape drive.
This issue started showing as my weekly backup to tape thru Backup Exec to a Dell tape drive got slow. The backup full ran for about 24 hours at 2,291 MB/min. This is normal. However, since July 2022 the weekly backup has taken about 3 days and run at about 645 MB/min. I am transitioning to a Synology Unit and cloud backups but have not completed the move and setup. So, I still need these backups to take off site until that is complete. End the end this is not the issue.
So I focused on the Back Exec Software, the Tape Drive and took a case with Veritas. They went thru things thoroughly and we did things like:
Updated the Backup Exec Software to the latest and greatest
Cleaned the tape drive
Truncated the Catalogs for Backup Exec after 13 months
Rebooted tape drive, then rebooted the server Backup Exec is on and then rebooted the servers that has the data it is backing up (mainly file server).
Virus scanning is not being done at the start of this backup. It does kick in about 30 hours after the start of the backup but makes no difference a far as I can tell in the logs. The virus software had been running for months as it is now.
Upgraded drivers/firmware on the Tape Drive
Veritas checked settings
Veritas looked at backup and debug logs from Backup Exec
Ran Veritas Testing
Swapped out SCSI cable from Server to Tape drive
IN THE END - We did some speed tests copying from servers to servers. We are getting about 10 MBs no matter what server I am coping from/to. So I am being told this is a network issue. It seems the slow speed is constant. However, my users are not complaining. So now I am trying to figure out the next steps to what is the cause. Switch, Port - something else?
I did check the wiring to the switches, and all looks good. There are no extra Ethernet cables and the switches are not connected through Ethernet cables, only cables using the SFP ports with the specific cables. They are setup correctly (from 1 to 2).
Settings or cables to switches have not been changed or altered lately. I have two Dell N1524’s (24 port) and 1 Dell N1548 (48 port). I do not have a VLAN setup. Dell did not setup when I had two go bad and they got replaced. I can log into the switches through one ip address but not sure what to setup or check while logged in.
Wondering if anyone can help me track the issue down with means and methods to do so. Let me know what other information may be helpful.