Payment Gateway Service location

Hi,  

We upgraded to v12.5.1 and have since experienced slowness in our credit card processing in the evening.  

Our servers are located on a SAN that is managed by the University IT group.  They perform a backup of the SAN starting at 6 pm.  That is when we see our cc processing times jump from 1-2 seconds to 5-20 seconds.   

Last season (year), before the v12.5.1 upgrade, I can see in the PGS logs that there was a slowdown that started at 6 pm but it added only a few second, meaning it wasn't noticeable.  This season it adds enough seconds that can make a transaction take a minute or longer & when there is a line at the Box Office it gets uncomfortable for the patrons and sellers.   

I want to jump right to a solution and wonder if moving the PGS (payment gateway service) to the Database server will fix the slow response times and speed up the cc processing.  

But...I don't know exactly why it is slowing down.  I did some netsh traces on both servers and see a sql read/write that happens btwn the cc and db servers using the SMB2 protocol that significantly slows down starting at 6 pm (when the backup starts).  

Has anyone moved the PGS to the DB server and found an improvement or deterioration of Tessitura?    I have read 2 posts that talk about where to put the PGS when you move to vantiv or elements and I understand that there is a PCI benefit to putting it not on a public ip address.  but putting the PGS on the webapi server would lighten the load for sql server.   sounds like it is a toss up.  

Any feedback is appreciated.  Especially if you can tell me what is happening with sql query using smb2 protocol - logging?

Thanks, Gretchen