Connecting to Azure SQL DB from IIS Web App on Azure VM

3
votes

I'm currently in the process of doing a proof of concept of moving from our current IAAS provider to Azure. We're currently just serving multiple LOB Web Apps on a 2 tier setup consisting of:

  1. Web Tier/Box 1: Web facing with IIS holding all Web Applications
  2. SQL Tier/Box 2: Non web facing. Web box talks directly to SQL box inside network.

Im wanting to run this as the following setup inside Azure: 1. Azure VM: This VM will be web tier. Due to legacy parts of our apps it would not fit within websites or Cloud services. 2. Azure SQL DB's: We will just push all our SQL database into Azure DB's and connect to them from the VM.

I've got this setup and working. The only problem is there is a major latency hit which seems to be from the VM web app talking to azure database. Im connecting to the SQL Azure DB with the connection string provided through the portal. Is there any reason that the connection is so slow (sometimes latency > 4 secs)? Is there any firewall or end point rules that i need to set? Or is this setup not optimal?

Thanks

1
sql-serverazureazure-sql-databaseazure-virtual-machine
Are you sure the VM and the Azure SQL are in the same region? THis could explain the latency – Erik Oppedijk
Hi Erik, Yep vm and sql are in same region. Thanks – Matt
Which tier the sql database running? Basic or standard? It does have a longer latency based on my test compare with the sql server running on vm – liuhongbo
Hi liuhongbo. I was running Basic. I've just moved it up to Standard with 50 DTU's and will benchmark with that. I've setup a vm running both the web tier and sql on the one box and the latency is gone. I just wanted to do that to rule out anything else. – Matt

1 Answers

2
votes

I found the issue was due to the performance level I had set on the SQL Azure DB. I used "Quick Create" and by default it sets the Performance Level to "Basic". I found this setting within the tabs of the Azure DB management Portal.

Setting it to "Standard" or "Premium" which increased the DTU's and boosted the performance of database transactions back to what I was expecting.

Thanks for the help in the comments.