Increase RAM usage for IIS server

Question

I am running a large scale ERP system on the following server configuration. The application is developed using AngularJS and ASP.NET 4.5

Dell PowerEdge R730 (Quad Core 2.7 Ghz, 32 GB RAM, 5 x 500 GB Hard disk, RAID5 configured) Software: Host OS is VMWare ESXi 6.0 Two VMs run on VMWare ESXi .. one is Windows Server 2012 R2 with 16 GB memory allocated ... this contains IIS 8 server with my application code Another VM is also Windows Server 2012 R2 with SQL Server 2012 and 16 GB memory allocated .... this just contains my application database.

You see, I separated the application server and database server for load balancing purposes.

My application contains a registration module where the load is expected to be very very high (around 10,000 visitors over 10 minutes)

To support this volume of requests, I have done the following in my IIS server -> increase request queue in application pool length to 5000 -> enable output caching for aspx files -> enable static and dynamic compression in IIS server -> set virtual memory limit and private memory limit of each application pool to 0 -> Increase maximum worker process of each application pool to 6

I then used gatling to run load testing on my application. I injected 500 users at once into my registration module.

However, I see that only 40% / 45% of my RAM is being used. Each worker process is using only a maximum amount of 130 MB or so.

And gatling is reporting that around 20% of my requests are getting 403 error, and more than 60% of all HTTP requests have a response time greater than 20 seconds.

A single user makes 380 HTTP requests over a span of around 3 minutes. The total data transfer of a single user is 1.5 MB. I have simulated 500 users like this.

Is there anything missing in my server tuning? I have already tuned my application code to minimize memory leaks, increase timeouts, and so on.

Answer 1

There is a known issue with the newest generation of PowerEdge servers that use the Broadcom Network Chip set. Apparently, the "VM" feature for the network is broken which results in horrible network latency on VMs.

1. Head to Dell and get the most recent firmware and Windows drivers for the Broadcom.

2. Head to VMWare Downloads and get the latest Broadcom Driver

As for the worker process settings, for maximum performance, you should consider running the same number of worker processes as there are NUMA nodes, so that there is 1:1 affinity between the worker processes and NUMA nodes. This can be done by setting "Maximum Worker Processes" AppPool setting to 0. In this setting, IIS determines how many NUMA nodes are available on the hardware and starts the same number of worker processes.

Answer 2

I guess the 1 caveat to the answer you received would be if your server isn't NUMA aware/uses symmetric processing, you won't see those IIS options under CPU, but the above poster seems to know a good bit more than I do about the machine. Sorry I don't have enough street cred to add this as a comment. As far as IIS you may also want to make sure your app pool doesn't use default recycle conditions and pick a time like midnight for recycle. If you have root level settings applied the default app pool recycling at 29 hours may also trigger garbage collection against your child pool/causing delays even in concurrent gc where it sounds like you may benefit a bit from Gcserver=true. Pretty tough to assess that though.

Has your sql server been optimized for that type of workload? If your data isn't paramount you could squeeze faster execution times with delayed durability, then assess queries that are returning too much info for async io wait types. In general there's not enough here to really assess for sql optimizations, but if not configured right (size/growth options) you could be hitting a lot of timeouts due to growth, vlf fragmentation, etc.