Virtual Scanner Appliance Sizing

This topic helps you to choose a Virtual Scanner Appliance size.

Most virtualization platforms' default virtual scanner sizing is 4 CPU cores, 8 GB RAM, and 56 GB disk space. The maximum supported size for a scanner instance is 16 CPU cores and 16 GB RAM. The size of the virtual disk is fixed at 56 GB unless a user increases it in their virtual machine settings.

The default CPU:RAM: DISK ratio is sufficient for some customer cases. However, suppose your virtual scanner handles a high volume of scans and vast amounts of scan data, such as frequent web application scans for a web server that returns several MBs of pages. In that case, you may want to increase the sizing to prevent overloading the scanner and running out of resources. If you wish to use Parallel Scaling in your scan option profile performance settings, you need to increase it to at least 2:4 or move up to 4:8 to see if there is any advantage to turning this setting on.

You can change all three settings (CPU, RAM, and Disk Size). You may want a ratio of 1:2 for CPU: RAM and disk expansion also need to be proportional.

Increasing the disk size is only needed if you frequently encounter low disk space issues during scans. Otherwise, you do not need to increase the disk size even if you increase the CPU and memory.

If you want to increase the disk size, use the same ratio. For example, if you double the CPU and RAM, then double the disk size too. 

Work directly with your Technical Account Manager or Qualys Support for help with scanner capacity and sizing calculations based on your scanning needs. 

Increase Virtual Disk Size

You can only increase the disk size; reducing the size is not supported.  

Follow these steps to increase the virtual disk size: 

1. Stop the scanner instance.
2. Find the Hard Disk/Storage option in your scanner VM instance settings and increase the disk size.
3. Save your settings and start up your scanner.

Your scanner instance should generate the new disk size. It also automatically resizes all partitions and file systems.

Change CPU and RAM Size  

You can increase or decrease CPU cores and RAM.  

The maximum supported size for a scanner instance is 16 CPU cores and 16 GB RAM. Allocating more memory than this will be wasted.   

As mentioned earlier, the number of CPU cores must be proportional to the allocated RAM and disk space. Use a ratio of 1:2 for CPU: RAM. For example, 4 CPU cores with 8GB RAM or 8 CPU cores with 16 GB RAM.  

Follow the steps below to change the CPU/RAM allocated for a scanner instance: 

1. Stop the scanner instance.
2. Find the CPU/RAM options in your scanner VM instance settings and choose the desired size.  
3. Save your settings and start up your scanner.