Editing VM vCPUs and RAM

Virtual machine hardware settings determine the amount of Metered RAM and vCPU capacity that the VM consumes—larger VMs consume more Metered RAM and vCPU capacity. For information about how Metered RAM and vCPU capacity are calculated, see How usage is calculated.

Instructions

To edit the VM vCPU and RAM settings

Make sure the VM is fully powered off (not running or suspended).
We recommend that before you make any hardware changes to your VM, that you create a template of it. If any problems occur, you can restore your VM from this template.
Navigate to the VM Settings > Hardware page.

Show me how
1. Navigate to the environment that contains the VM you want to edit.
2. Click (Settings).
  
  If the Settings button isn’t visible, you don’t have permission to edit the VM settings. Work with your instructor or Skytap administrator to edit these settings.
3. The VM Settings page displays. Click the Hardware tab.
Under RAM, type the amount of RAM (in GB) for the VM.
Notes
- Higher RAM values enable higher values for vCPUs and Entitled capacity. For specific details, see the Entitled capacity and CPWlookup tables below.
- The maximum amount of RAM available for a single VM varies, depending on region.
- For AIX VMs – The minimum supported RAM is 2 GB.
Choose the number of vCPUs that the VM will use. The maximum vCPUs value is determined by RAM.

The maximum number of vCPUs can vary, depending on region. For a list of regional capabilities, see Skytap service limits.</p>
Choose the Entitled capacity for the VM. The maximum Entitled capacity value is determined by vCPUs.
Set vCPU sharing mode to either Uncapped or Capped.
- Capped – The VM can never exceed the entitled capacity, determined by the vCPUs and RAM values for the VM.
- Uncapped – The VM will automatically use any excess processor resources available in the shared resource pool, in excess of the entitled capacity.
Notes
- vCPU sharing mode helps control costs for applications that determine license cost, based on vCPU usage.
- Additional vCPU resources are not guaranteed and can change if the VM is restarted.
- Uncapped sharing mode can potentially increase cost for third-party software that is licensed based on vCPU usage.
Click Save.

Additional information

Follow vendor recommendations for the operating system and the installed applications when setting the CPU and RAM values. Generally:
- Additional CPU cores permit more concurrent system and application processes, which can improve system performance.
- Additional RAM allows more applications to be active and improves access speeds for data.

For Power VMs, set Entitled capacity (and approximate IBM i CPW) by changing the amount of RAM and the number of CPUs.

IBM i, AIX, and Linux (on Power) VMs up to four CPUs

The table below was calculated with the following formulas:

EC=MIN(vcpu_count,FLOOR(MAX(GB_ram/50,0.05),0.005))
vcpu_limit=MIN(ROUNDUP(EC*20,0),16)
CPW=EC*10618 (approximate)

Entitled Capacity and CPW for Power8 VMs

	CPU Cores
	1		2		3		4
RAM	EC	CPW	EC	CPW	EC	CPW	EC	CPW
1 GB	0.05	530	---	---	---	---	---	---
2 GB	0.05	530	---	---	---	---	---	---
3 GB	0.06	637	0.06	637	---	---	---	---
4 GB	0.08	849	0.08	849	---	---	---	---
5 GB	0.10	1,061	0.10	1,061	0.10	1,061	---	---
6 GB	0.12	1,274	0.12	1,274	0.12	1,274	---	---
7 GB	0.14	1,486	0.14	1,486	0.14	1,486	0.14	1,486
8 GB	0.16	1,698	0.16	1,698	0.16	1,698	0.16	1,698
16 GB	0.32	3,397	0.32	3,397	0.32	3,397	0.32	3,397
32 GB	0.64	6,795	0.64	6,795	0.64	6,795	0.64	6,795
48 GB	0.96	10,193	0.96	10,193	0.96	10,193	0.96	10,193
64 GB	1.00	10,618	1.28	13,591	1.28	13,591	1.28	13,591
128 GB	1.00	10,618	2.00	21,236	2.56	27,182	2.56	27,182
256 GB	1.00	10,618	2.00	21,236	3.00	31,854	4.00	42,472
512 GB	1.00	10,618	2.00	21,236	3.00	31,854	4.00	42,472
CPW values are approximate.

Entitled capacity for AIX and Linux (on Power) VMs

	CPU Cores
RAM	5	6	7	8	9	10	12	14	16
16 GB	0.32	0.32	0.32	0.32	---	---	---	---	---
24 GB	0.48	0.48	0.48	0.48	0.48	0.48	0.48	---	---
32 GB	0.64	0.64	0.64	0.64	0.64	0.64	0.64	0.64	0.64
48 GB	0.96	0.96	0.96	0.96	0.96	0.96	0.96	0.96	0.96
64 GB	1.28	1.28	1.28	1.28	1.28	1.28	1.28	1.28	1.28
128 GB	2.56	2.56	2.56	2.56	2.56	2.56	2.56	2.56	2.56
256 GB	5.00	5.12	5.12	5.12	5.12	5.12	5.12	5.12	5.12
512 GB	5.00	6.00	7.00	8.00	9.00	10.00	10.24	10.24	10.24

Notes

These tables provide common RAM and CPU core combinations for Entitled capacity and CPW. You can choose other values for both RAM and CPUs—the updated Entitled capacity value displays in the Skytap interface.
When you increase the RAM for a VM, Skytap does not automatically increase Entitled capacity.
Currently, a single IBM i VM supports a maximum of four CPU Cores (approximately 42,472 CPW).

Entitled Capacity and CPW for Power9 VMs

For Power VMs, set Entitled capacity (and approximate IBM i CPW) by changing the amount of RAM and the number of CPUs.

IBM i, AIX, and Linux (on Power) VMs up to four CPUs

The table below was calculated with the following formulas:

EC=MIN(vcpu_count,FLOOR(MAX(GB_ram/50,0.05),0.005))
vcpu_limit=MIN(ROUNDDOWN(EC*20,0),16)
CPW=EC*15000 (approximate)

	CPU Cores
	1		2		3		4
RAM	EC	CPW	EC	CPW	EC	CPW	EC	CPW
1 GB	0.05	750	---	---	---	---	---	---
2 GB	0.05	750	---	---	---	---	---	---
3 GB	0.06	900	0.06	900	---	---	---	---
4 GB	0.08	1,200	0.08	1,200	---	---	---	---
5 GB	0.10	1,500	0.10	1,500	0.10	1,500	---	---
6 GB	0.12	1,800	0.12	1,800	0.12	1,800	---	---
7 GB	0.14	2,100	0.14	2,100	0.14	2,100	0.14	2,100
8 GB	0.16	2,400	0.16	2,400	0.16	2,400	0.16	2,400
16 GB	0.32	4,800	0.32	4,800	0.32	4,800	0.32	4,800
24 GB	0.48	7,200	0.48	7,200	0.48	7,200	0.48	7,200
32 GB	0.64	9,600	0.64	9,600	0.64	9,600	0.64	9,600
48 GB	0.96	14,400	0.96	14,400	0.96	14,400	0.96	14,400
64 GB	1.00	15,000	1.28	19,200	1.28	19,200	1.28	19,200
128 GB	1.00	15,000	2.00	30,000	2.56	38,400	2.56	38,400
256 GB	1.00	15,000	2.00	30,000	3.00	45,000	4.00	60,000
512 GB	1.00	15,000	2.00	30,000	3.00	45,000	4.00	60,000
CPW values are approximate.

Entitled capacity for AIX and Linux (on Power) VMs

	CPU Cores
RAM	5	6	7	8	9	10	12	14	16
16 GB	0.32	0.32	0.32	0.32	---	---	---	---	---
24 GB	0.48	0.48	0.48	0.48	0.48	0.48	0.48	---	---
32 GB	0.64	0.64	0.64	0.64	0.64	0.64	0.64	0.64	0.64
48 GB	0.96	0.96	0.96	0.96	0.96	0.96	0.96	0.96	0.96
64 GB	1.28	1.28	1.28	1.28	1.28	1.28	1.28	1.28	1.28
128 GB	2.56	2.56	2.56	2.56	2.56	2.56	2.56	2.56	2.56
256 GB	5.00	5.12	5.12	5.12	5.12	5.12	5.12	5.12	5.12
512 GB	5.00	6.00	7.00	8.00	9.00	10.00	10.24	10.24	10.24

Notes

These tables provide some common RAM and CPU core combinations for Entitled capacity and CPW.
You can choose other values for both RAM and CPUs—the updated Entitled capacity value displays in the Skytap interface.
When you increase the RAM for a VM, Skytap does not automatically increase Entitled capacity.
Currently, a single IBM i VM supports a maximum of four CPU Cores (approximately 60,000 CPW).
If you change Entitled capacity for an active Power VM, it will display updated values but those values aren't applied to the VM until it's completely shut down, and then started again.
Some older operating system versions require Power8 compatibility mode, which reduces processor performance and CPW values to less than what these tables display.

Editing VM vCPUs and RAM

Contents

Instructions

To edit the VM vCPU and RAM settings

Additional information

IBM i, AIX, and Linux (on Power) VMs up to four CPUs

Entitled capacity for AIX and Linux (on Power) VMs

IBM i, AIX, and Linux (on Power) VMs up to four CPUs

Entitled capacity for AIX and Linux (on Power) VMs