VM Details – Xen Test
This test monitors the amount of the physical server's resources that each guest on an XenServer is taking up. Using the metrics reported by this test, administrators can determine which virtual guest is taking up most CPU, which guest is generating the most network traffic, which guest is taking up the maximum memory utilization, which guest has the maximum disk activity, etc. Note that the amount of resources taken up by a virtual guest will be limited by the resource allocations that have been made by administrators. For example, an administrator could cap the amount of memory that a specific guest may take. Also, virtual guests can be organized into resource pools, and allocation of resources can be made at the resource-pool level. In this case, virtual guests allocated to the same resource pool contend for the resources allocated to the resource pool.
Target of the test : A XenServer host
Agent deploying the test : An internal/remote agent
Outputs of the test : One set of results for each guest configured on the XenServer host
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Measurement | Description | Measurement Unit | Interpretation | ||||||
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Is VM powered on? : |
Whether the virtual machine is currently running on the XenServer host or no. |
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While the test reports a wide variety of other metrics too for virtual machines that are alive, only the powered on status is indicated for virtual machines that are currently not available. The value Yes for this measure indicates that the guest is up and running. The value No could indicate that the guest has been powered-off; it could also indicate that XenMotion has moved the guest to a different server. The numeric values that correspond to each of the powered-on states discussed above are listed in the table below:
Note: By default, this measure reports Yes or No to indicate VM status. The graph of this measure however, represents the status of a VM using the numeric equivalents - 0 or 1. |
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Physical CPU usage: |
Indicates the percentage of physical CPU used by the guest. |
Percent |
A high value for this measure indicates a virtual machine that is using a lot of the processor - possibly because one or more processes on this VM are taking a lot of CPU. |
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Free physical memory: |
Indicates the amount of memory available for use with the guest.
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MB |
Ideally, this value should be high. A low or consistent decrease in this value denotes that the application(s) executing on the guest are consuming memory excessively. You might want to consider increasing the memory allocated to the guest. XenServer Enterprise and XenServer Standard allow that a Linux/Windows VM can use up to 32GB of memory. Moreover, Xen has implemented a balloon driver concept for each domain, enabled independently, that allows the operating system to adjust its current memory allocation up to the maximum limit configured. This allows “unused” allocation to be consumed in other areas, potentially allowing for stable over-commitment of memory resources. Because of this constantly changing memory allocation, memory is allocated and freed dynamically at a granularity of the page-level. |
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Total physical memory allocated: |
Indicates the amount of physical memory currently allocated to the guest. |
MB |
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Used physical memory: |
Indicates the amount of memory used by the guest. |
MB |
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Usage of allocated memory: |
Indicates the percentage of allocated memory that is being used by the guest. |
Percent |
High memory consumption over long periods can deplete the free memory on the guest, causing prolonged delays in the execution of the application(s) hosted by the guests. |
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Disk capacity: |
Indicates the total allocated disk space of the guest. |
MB |
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Disk read rate: |
Indicates the rate at which the guest read from the disk. |
Kbytes/Sec |
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Disk write rate: |
Indicates the rate at which the guest wrote data to the disk. |
Kbytes/Sec |
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Network data received: |
Indicates the network I/O reads performed by the guest. |
Mbps |
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Network data transmitted: |
Indicates the network I/O writes performed by the guest. |
Mbps |
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Virtual CPU utilization: |
Indicates the percentage of allocated CPU resources that this VM is currently using. |
Percent |
Comparing the value of this measure across VMs will enable you to accurately identify the VMs on which CPU-intensive applications are executing. |
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Virtual CPUs: |
Indicates the number of virtual CPU cores allocated to this VM. |
Number |
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Disk read and write rate: |
Indicates the rate at which read-write requests were processed by this VM. |
Kbytes/Sec |
Compare the value of this measure across VMs to know on which VM I/O activity was abnormally high. |
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Network data sent and received: |
Indicates the rate at which network I/O is processed by this VM. |
Mbps |
Compare the value of this measure across VMs to know on which VM network I/O activity was abnormally high. |
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Total IOPS: |
Indicates the rate at which I/O operations are performed by this VM. |
Requests/Sec |
This measure is a good indicator of the I/O processing capacity of the VM. A high value is hence desired for this measure. A consistent drop in this value could indicate a processing bottleneck. In such a situation, you can compare the value of the Read operations and Write operations measures of the corresponding VM to figure out where the bottleneck lies – in reading data from the VM? or in writing to the VM? |
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Read operations: |
Indicates the rate at which this VM services read requests. |
Requests/Sec |
Ideally, the value of this measure should be high. A steady drop in this value indicates a slowdown in processing read requests. Compare the value of this measure across VMs to know which VM is the slowest in responding to read requests. |
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Write operations: |
Indicates the rate at which this VM services write requests. |
Requests/Sec |
Ideally, the value of this measure should be high. A steady drop in this value indicates a slowdown in processing write requests. Compare the value of this measure across VMs to know which VM is the slowest in responding to write requests. |
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Time spent waiting for I/O: |
Indicates the percentage of time the host’s CPU was waiting for this VM to complete I/O processing. |
Percent |
A high value for this measure indicates that the VM is taking too long to complete I/O processing. This hints at a probable processing bottleneck with the VM. |
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Average queue size: |
Indicates the average number of I/O requests to this VM that are in queue for processing. |
Number |
If the value of this measure grows consistently, it indicates that the VM is unable to process requests quickly enough to clear the queue. The VM with the maximum number of queued requests could be experiencing a serious I/O processing bottleneck. To identify this VM, compare the value of this measure across VMs. |
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Current requests in flight: |
Indicates the number of I/O requests to this VM that are currently being processed. |
Number |
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Current sessions: |
This measure is relevant only for monitoring of virtual desktops (i.e., for Citrix XenServer - VDI servers). When reporting metrics for specific users, this metric indicates the number of sessions that each user has currently logged into; this measure will be available only if the test reports measures per currently logged in user. |
Number |
This is a good indicator of how busy the user is. The detailed diagnosis of this measure, if enabled, reveals the guests to which the user is currently logged on to. |
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Virtual CPUs full run: |
Indicates the percentage of the time that the vCPUs were running on this VM. |
Percentage |
A high value for this measure indicates that the vCPUs are using a lot of the physical CPU resources for prolonged duration. |
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Virtual CPUs partial run: |
Indicates the percentage of time that some of the total vCPUs were running, and others were blocked on this VM. |
Percentage |
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Virtual CPUs idle: |
Indicates the percentage of time that the vCPUs were blocked or offline on this VM. |
Percentage |
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Virtual CPUs concurrency hazard: |
Indicates the percentage of time that some of the total vCPUs were running, and other vCPUs were waiting for the physical CPU. |
Percentage |
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Virtual CPUs full contention: |
Indicates the percentage of time that the vCPUs on this VM were waiting for the physical CPU. |
Percentage |
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Virtual CPUs partial contention: |
Indicates the percentage of time that some of the total vCPUs were waiting for the physical CPU, and others were blocked. |
Percentage |