This document explains how usage is calculated for Virtual Data Centers in the system. Understanding these calculations helps you track resource consumption and manage costs effectively.
- What is Usage Tracking?
- Types of Usage Tracked
- How Usage is Calculated
- Understanding the Usage Report
- Frequently Asked Questions
Usage tracking monitors how much computing resources your Virtual Data Center consumes over time. This includes:
- CPU time - How long processors are used
- Memory time - How long memory (RAM) is allocated
- Storage space - How much disk space is used
- Backup storage - Space used for backups
- ISO storage - Space used for ISO images
The system records these metrics continuously and provides detailed reports showing consumption patterns.
CPU Usage
- Measured in core-hours (number of CPU cores × hours used)
- Example: A 4-core virtual machine running for 2 hours = 8 core-hours
Memory Usage
- Measured in GiB-hours (Gibibytes of memory × hours used)
- Example: A VM with 8 GiB RAM running for 3 hours = 24 GiB-hours
VM Storage
- Tracks disk space allocated to virtual machines
- Measured in GiB-hours (storage capacity × hours)
- Includes all virtual disks attached to VMs
Catalogue Storage
- Storage used for templates and catalogs
- Combined with VM storage in reports
- Space used to store VM backups
- Measured in GiB-hours
- Only counts while backups exist
- Space used for ISO images (installation media)
- Measured in GiB-hours
- Shared across the data center
The system uses a time-interval approach:
- Snapshot Recording: The system takes regular snapshots of resource states
- Interval Calculation: Usage between snapshots is calculated based on the previous state
- Accumulation: All intervals are summed for the reporting period
Scenario: A virtual machine with 2 CPU cores and 4 GiB RAM
| Time |
State |
Duration |
CPU Usage |
Memory Usage |
| 9:00 AM |
Started |
- |
- |
- |
| 10:00 AM |
Running |
1 hour |
2 core-hours |
4 GiB-hours |
| 12:00 PM |
Running |
2 hours |
4 core-hours |
8 GiB-hours |
| 1:00 PM |
Stopped |
1 hour |
2 core-hours |
4 GiB-hours |
| 3:00 PM |
Stopped |
2 hours |
0 core-hours |
0 GiB-hours |
Total Usage: 8 core-hours CPU, 16 GiB-hours Memory
-
Usage only accumulates when resources are active
- VMs accumulate CPU/Memory usage only when powered on
- Storage accumulates whenever space is allocated
-
Pro-rated calculation
- If a VM runs for 30 minutes, it counts as 0.5 hours
- Partial hours are calculated precisely
-
Historical tracking
- Deleted VMs still show in reports as "[Deleted] VM Name"
- This ensures complete usage history
¶ Understanding the Usage Report
-
Summary Section
- Total date range duration
- Current time and timezone
- VDC name and details
-
Visual Charts
- CPU usage over time
- Memory usage over time
- Shows consumption patterns
-
Detailed Tables
Resources Tab
- VM-by-VM breakdown
- Start/stop times for each period
- Individual CPU and memory hours
Storage Tabs
- Storage policy usage
- Backup storage consumption
- ISO storage allocation
Duration: Total time in the reporting period (e.g., 720 hours for 30 days)
CPU Hours: Sum of (CPU cores × hours running) for all VMs
Memory Hours: Sum of (Memory GiB × hours running) for all VMs
Status Indicators:
- 🟢 Started: VM is running and consuming resources
- 🔴 Stopped: VM is powered off, no CPU/memory consumption
A: The report shows the last state change. If a VM was running earlier in the period before being stopped, it accumulated usage during the running time.
¶ Q: What's the difference between allocated and consumed resources?
A:
- Allocated: Resources reserved for your VDC (shown as capacity)
- Consumed: Resources actually used (shown as usage)
A: Usage data is recorded in real-time when VMs change state (start/stop) and when storage is modified.
A: To maintain accurate historical records, VMs that were deleted during the reporting period still show their usage before deletion.
A:
- Resource usage (CPU/Memory): Only counts when VM is running
- Storage usage: Counts continuously while space is allocated
A: Yes, usage reports can be exported for further analysis or record-keeping.
A: All calculations use UTC time internally. The display can show both UTC and your local timezone.