Scaling Considerations
This section contains information that
helps you estimate CPU, RAM, and disk requirements for vSLX entities.
This information is valid for both installation options:
Resource requirements
The following table lists virtual CPU (vCPU), memory, and storage requirements needed to emulate SLX-OS entities.
Table 1. Resources required for vSLX entities
Entity
|
CPU cores
|
Virtual memory (RAM)
|
Min. disk size
|
Max. disk size
|
SLX 9540 template
|
—
|
—
|
9 GB
|
9 GB
|
SLX 9540 instance
|
1
|
8 GB
|
1 GB
|
25 GB
|
Memory swapping
If your storage technology is solid-state drive (SSD)—rather than rotational hard-disk drive (HDD)—memory swapping into the SSD can reduce the physical "Virtual memory (RAM)" values in the preceding table. For example, a swap space of 32 GB supports four additional SLX 9540 instances.
Virtual machines (VMs)
One Virtual Machine (VM) can emulate one virtual
device. vSLX uses several methodologies to optimize resource utilization among VMs:
- Space efficiency: QEMU snapshot
technology is used for chassis (virtual device) image creation from a
template. When a chassis is created, the initial storage size is less than
200 KB. As a chassis is configured, the disk size increases.
- Memory efficiency: QEMU and kernel
same-page merging (KSM) support memory de-duplication among VMs, which
enables sharing memory for duplicate blocks. These technologies reduce
memory requirements by up to 60 percent.
- CPU over-provisioning: When vSLX is
used for normal control-plane traffic, CPU consumption does not exceed two
vCPUs for each VM. This efficiency allows for flexibility in
over-subscribing CPU resources, allowing vSLX to scale well.
SLX 9540 scaling calculations
The following equations estimate optimized server resources needed for virtual SLX 9540 devices (each SLX 9540 instance is one VM):
- CPUSLX 9540 (number of cores) = 1 * <number-of-VMs>
- MEM
SLX 9540 (GB) = 8 * <number-of-VMs>
- STORAGESLX 9540 (GB) = TemplateSize
SLX 9540 + (2 * <number-of-VMs>)
The following examples estimate the server resources needed to emulate 10 SLX 9540 instances:
- CPU = 1 * 10 = 10 cores
- MEM = 8 * 10 = 80 GB
- STORAGE = 6 + (2 x 10) = 26 GB