Disk Space – Xen Test

This test reports the space usage of every volume group supported by the Citrix Hypervisor host.

Target of the test : A Citrix Hypervisor host

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each volume group on a Citrix Hypervisor host

Configurable parameters for the test
Parameter	Description
Test period	How often should the test be executed.
Host	The host for which the test is to be configured.
Xen User, Xen Password and Confirm Password	To enable the eG agent to connect to the XenServer API for collecting statistics of interest, this test should login to the target hypervisor as a root user. Provide the name of the root user in the Xen User text box. Root user privileges are mandatory when monitoring a XenServer 5.5 (or below). However, if you are monitoring XenServer 5.6 (or above) and you prefer not to expose the credentials of the root user, then, you have the option of configuring a user with pool-admin privileges as the Xen User. If you do not want to expose the credentials of a root/pool-admin user, then you can configure the tests with the credentials of a Xen User with Read-only privileges to the XenServer. However, if this is done, then the Xen Uptime test will not run, and the Xen CPU and Xen Memory tests will not be able to report metrics for the control domain descriptor. To avoid such an outcome, do the following before attempting to configure the eG tests with a Xen User who has Read-only privileges to the Citrix Hypervisor: Modify the target hypervisor's configuration in the eG Enterprise. For this, follow the Infrastructure -> Components -> Add/Modify menu sequence, pick Citrix Hypervisor as the Component type, and click the Modify button corresponding to the target hypervisor. In the MODIFY COMPONENT DETAILS page that then appears, make sure that the os is set to Xen and the Mode is set to SSH. Then, in the same page, proceed to provide the User and Password of a user who has the right to connect to the XenServer console via SSH. Then, click the Update button to save the changes. Once this is done, you can configure the eG tests with the credentials of a Xen User with Read-only privileges. The password of the specified Xen User needs to be mentioned in the Xen Password text box. Then, confirm the Xen Password by retyping it in the Confirm Password text box.
SSL	By default, the Citrix Hypervisor is not SSL-enabled. This indicates that by default, the eG agent communicates with the target hypervisor using HTTP. Accordingly, the SSL flag is set to No by default. If you configure the target hypervisor to use SSL, then make sure that the SSL flag is set to Yes, so that the eG agent communicates with the target hypervisor using HTTPS. Note that a default SSL certificate comes bundled with every Citrix Hypervisor installation. If you want the eG agent to use this default certificate for communicating with an SSL-enabled Citrix Hypervisor, then no additional configuration is required. However, if you do not want to use the default certificate, then you can generate a self-signed certificate for use by the target hypervisor. In such a case, you need to explicitly follow the broad steps given below to enable the eG agent to communicate with the target hypervisor via HTTPS: Obtain the server-certificate for the Citrix Hypervisor Import the server-certificate into the local certificate store of the eG agent For a detailed discussion on each of these steps, refer to the Troubleshooting section of this document.
Webport	By default, in most virtualized environments, the target hypervisor listens on port 80 (if not SSL-enabled) or on port 443 (if SSL-enabled). This implies that while monitoring an SSL-enabled Citrix hypervisor, the eG agent, by default, connects to port 443 of the server to pull out metrics, and while monitoring a non-SSL-enabled Citrix hypervisor, the eG agent connects to port 80. Accordingly, the webport parameter is set to 80 or 443 depending upon the status of the ssl flag. In some environments however, the default ports 80 or 443 might not apply. In such a case, against the webport parameter, you can specify the exact port at which the target hypervisor in your environment listens so that the eG agent communicates with that port.

Measurements made by the test
Measurement	Description	Measurement Unit	Interpretation
Total physical extents	Indicates the total number of physical extents on this volume group	Number	For the Total descriptor, this measure will report the total number of physical extents across all volume groups on the XenServer host.
Used physical extents	Indicates the number of physical extents allocated to this volume group.	Number	For the Total descriptor, this measure will report the total number of physical extents allocated to all volume groups on the XenServer host.
Free physical extents	Indicates the number of allocated extents that are still unused by this volume group.	Number	For the Total descriptor, this measure will report the total number of unused physical extents in all volume groups on the XenServer host. Ideally, the value of this measure should be high.
Physical extent size	Indicates the current size of the physical extents in this volume group.	MB	For the Total descriptor, this measure will report the total size of the physical extents in all volume groups on the XenServer host.
Disk space in use by VMs	Indicates the space in this volume group that is used by VMs.	GB	For the Total descriptor, this measure will report the total space used across all volume groups on the XenServer host. A high value indicates excessive utilization of a volume group. If the value of this measure is high for the Total descriptor, it indicates that the usage across volume groups is very high.
Space available for allocation to new VMs	Indicates the amount of free space on this volume group.	GB	This measure reports the difference between the Total disk capacity measure and the Disk space in use by VMs measure. Ideally, the value of this measure should be high. A very low value could indicate that one/more vMs are utilizing the allocated disk space excessively. To confirm this, check the value of the Disk space in use by VMs measure; if this value is very high, it indicates that the VMs are eroding disk space. For the Total descriptor, this measure will report the total disk space that is free across all volume groups, and can be allocated to new VMs.
Usage of allocated space	Indicates the percentage of space allocated from this volume group that is used by VMs.	Percent	A value close to 100% is a cause for concern, as it indicates that one/more VMs are draining the disk space. If the situation persists or aggravates, VMs will experience a severe space crunch, which can bring all VM operations to a halt. To avoid this, you will have to isolate the VMs that are eroding the allocated disk space, clear unnecessary files from the disks of those VMs, and make additional space. Else, you should allocate more space to such VMs. For the Total descriptor, this measure will report the percentage of the total space allocations from all volume groups that is currently utilized by all VMs on the host. If the Total descriptor of this measure reports a high value, it indicates that the VMs on the host are consuming too much space that is allocated to them. You can then compare the value of this measure across volume groups to know which volume group is being used excessively.
Usage of disk capacity	Indicates the percentage of the capacity of this volume group that is currently in use.	Percent	Ideally, the value of this measure should be low. A very high value indicates that the volume group is running out of space. Under such circumstances, you may want to check the value of Disk capacity allocated to VMs and the Disk space in use by VMs measures to know what is causing the space erosion – is it due to over-allocation of space to VMs? Or abnormal usage of space by the VMs? For the Total descriptor, this measure will report the percentage of the total disk capacity across all volume groups that is currently used. If the Total descriptor of this measure reports a high value, it indicates excessive usage of storage space across all volume groups. You can then compare the value of this measure across volume groups to know which volume group is being used excessively.
Total disk capacity	Indicates the total capacity of this volume group.	GB	For the Total descriptor, this measure will report the total disk capacity of the host across all volume groups.
Disk capacity allocated to VMs	Indicates the total disk space in this volume group that has been allocated to all VMs on the host.	GB	For the Total descriptor, this measure will report the total space that is allocated to all VMs from all volume groups on the host.
Disk capacity available for allocation	Indicates the total disk space in this volume group that is yet to be allocated to VMs.	GB	For the Total descriptor, this measure will report the sum of the space in all volume groups that is still to be allocated to VMs.
Disk space allocated to VMs	Indicates the percentage of disk space in this volume group that has been allocated to VMs.	Percent	A very high value for this measure indicates that too much disk space has been allocated to the VMs. In such a situation, the host may not have enough disk space for its own operations, and this may cause the host’s performance to deteriorate. For the Total descriptor, this measure will report the percentage of the total disk space across all volume groups that is allocated to all VMs on the host. If the Total descriptor of this measure reports a high value, it indicates that overall, too much storage space has been allocated to VMs. You can then compare the value of this measure across volume groups to know from which volume group the maximum space has been allocated.
Usage of allocated space	Indicates the percentage of space allocated from this volume group that has been used by the VMs.	Percent	A high value for this measure indicates excessive usage of a volume group by the VMs. For the Total descriptor, this measure will indicate what percentage of the total allocated disk space (across all volume groups) that has been utilized by the VMs.