VM Datastores Test

This test monitors the availability, usage, and I/O activity of every datastore allocated to every virtual machine on an ESX server. If users are unable to access a VM, then this test will enable administrators to determine whether it can be attributed to the non-availability of the datastore allocated to the VM, the lack of space in the datastore, or a high I/O latencies experienced by the datastore.

Target of the test : An ESX server host

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each datastore used by each VM configured on the ESX host being monitored.

Configurable parameters for the test

  1. Test period - How often should the test be executed
  2. Host - The host for which the test is to be configured.
  3. port - The port at which the specified host listens. By default, this is NULL.
  4. esx user and esx password - In order to enable the test to extract the desired metrics from a target ESX server, you need to configure the test with an ESX USER and ESX PASSWORD. The user credentials to be passed here depend upon the mechanism used by the eG agent for collecting performance statistics from the ESX server and its VMs. These monitoring methodologies and their corresponding configuration requirements have been discussed hereunder:

    • Monitoring using the web services interface of the ESX server: Starting with ESX server 3.0, a VMware ESX server offers a web service interface using which the eG agent collects metrics from the ESX server. The VMware VI SDK is used by the agent to implement the web services interface. To use this interface for monitoring, this test should be configured with an ESX USER who has “Read-only” privileges to the target ESX server. By default, the root user is authorized to execute the test. However, it is preferable that you create a new user on the target ESX host and assign the “Read-only” role to him/her. The steps for achieving this have been elaborately discussed in Creating a New User with Read-Only Privileges to the ESX Server section.

      ESX servers terminate user sessions based on timeout periods. The default timeout period is 30 mins. When you stop an agent, sessions currently in use by the agent will remain open for this timeout period until ESX times out the session. If the agent is restarted within the timeout period, it will open a new set of sessions. If you want the eG agent to close already existing sessions before it opens new sessions, then you would have to configure all the tests with the credentials of an ESX user with permissions to View and stop sessions (prior to vSphere/ESX server 4.1, this was called the View and Terminate Sessions privilege). To know how to grant this permission to an ESX user, refer to .

    • Monitoring using the vCenter in the target environment: By default, the eG agent connects to each ESX server and collects metrics from it. While this approach scales well, it requires additional configuration for each server being monitored. For example, separate user accounts may need to be created on each server for read-only access to VM details. While monitoring large virtualized installations however, the agents can be optionally configured to monitor ESX servers using the statistics already available with different vCenter installations in the environment.

    In this case therefore, the ESX USER and ESX PASSWORD that you specify should be that of an Administrator or Virtual Machine Administrator in vCenter. However, if, owing to security constraints, you prefer not to use the credentials of such users, then, you can create a special role on vCenter with ‘Read-only’ privileges.

    Refer to Assigning the ‘Read-Only’ Role to a Local/Domain User to vCenter section to know how to create a user on vCenter.

    If the ESX server for which this test is being configured had been discovered via vCenter, then the eG manager automatically populates the esx user and esx password text boxes with the vCenter user credentials using which the ESX discovery was performed.

    Like ESX servers, vCenter servers too terminate user sessions based on timeout periods. The default timeout period is 30 mins. When you stop an agent, sessions currently in use by the agent will remain open for this timeout period until vCenter times out the session. If the agent is restarted within the timeout period, it will open a new set of sessions. If you want the eG agent to close already existing sessions before it opens new sessions, then you would have to configure all the tests with the credentials of a vCenter user with permissions to View and stop sessions (prior to vCenter 4.1, this was called the View and Terminate Sessions permission). To know how to grant this permission to a user to vCenter, refer to Creating a Special Role on vCenter and Assigning the Role to a Local/Domain User section.

    When the eG agent is started/restarted, it first attempts to connect to the vCenter server and terminate all existing sessions for the user whose credentials have been provided for the tests. This is done to ensure that unnecessary sessions do not remain established in the vCenter server for the session timeout period.  Ideally, you should create a separate user account with the required credentials and use this for the test configurations. If you provide the credentials for an existing user for the test configuration, when the eG agent starts/restarts, it will close all existing sessions for this user (including sessions you may have opened using the Virtual Infrastructure client). Hence, in this case, you may notice that your VI client sessions are terminated when the eG agent starts/restarts.

  5. confirm password - Confirm the password by retyping it here.
  6. ssl - By default, the ESX server is SSL-enabled. Accordingly, the SSL flag is set to Yes by default. This indicates that the eG agent will communicate with the ESX server via HTTPS by default.

    Like the ESX sever, the vCenter is also SSL-enabled by default. If you have chosen to use the vCenter for monitoring, then you have to set the SSL flag to Yes.

  7. webport - By default, in most virtualized environments, the vSphere/ESX server and vCenter listen on port 80 (if not SSL-enabled) or on port 443 (if SSL-enabled). This implies that while monitoring an SSL-enabled vSphere/ESX server directly, the eG agent, by default, connects to port 443 of the vSphere/ESX server to pull out metrics, and while monitoring a non-SSL-enabled server, the eG agent connects to port 80. Similarly, while monitoring a vSphere/ESX server via an SSL-enabled vCenter, the eG agent connects to port 443 of vCenter to pull out the metrics, and while monitoring via a non-SSL-enabled vCenter, the eG agent connects to port 80 of vCenter. 

    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 vSphere/ESX server or vCenter in your environment listens so that the eG agent communicates with that port.

  8. VIRTUAL CENTER - If the eG manager had discovered the target ESX server by connecting to vCenter, then the IP address of the vCenter server used for discovering this ESX server would be automatically displayed against the vIRTUAL center parameter; similarly, the esx user and esx password text boxes will be automatically populated with the vCenter user credentials, using which ESX discovery was performed.

    If this ESX server has not been discovered using vCenter, but you still want to monitor the ESX server via vCenter, then select the IP address of the vCenter host that you wish to use for monitoring the ESX server from the vIRTUAL center list. By default, this list is populated with the IP address of all vCenter hosts that were added to the eG Enterprise system at the time of discovery. Upon selection, the esx user and esx password that were pre-configured for that vCenter server will be automatically displayed against the respective text boxes.

    On the other hand, if the IP address of the vCenter server of interest to you is not available in the list, then, you can add the details of the vCenter server on-the-fly, by selecting the Other option from the vIRTUAL center list. This will invoke the add vcenter server details page. Refer to Adding the Details of a vCenter Server for VM Discovery section.

    On the other hand, if you want the eG agent to behave in the default manner -i.e., communicate with each ESX server for monitoring it - then set the VIRTUAL CENTER parameter to ‘none’. In this case, the ESX USER and ESX PASSWORD parameters can be configured with the credentials of a user who has at least ‘Read-only’ privileges to the target ESX server.

  9. inside view using - By default, this test communicates with every VM remotely and extracts “inside view” metrics. Therefore, by default, the inside view using flag is set to Remote connection to VM (Windows).

    Typically, to establish this remote connection with Windows VMs in particular, eG Enterprise requires that the eG agent be configured with domain administrator privileges. In high-security environments, where the IT staff might have reservations about exposing the credentials of their domain administrators, this approach to extracting “inside view” metrics might not be preferred. In such environments therefore, eG Enterprise provides administrators the option to deploy a piece of software called the eG VM Agent (Windows) on every Windows VM; this VM agent allows the eG agent to collect “inside view” metrics from the Windows VMs without domain administrator rights. Refer to Configuring the eG Agent to Collect Current Hardware Status Metrics section for more details on the eG VM Agent. To ensure that the “inside view” of Windows VMs is obtained using the eG VM Agent, set the inside view using flag to eG VM Agent (Windows).

  10. exclude vms - Administrators of some virtualized environments may not want to monitor some of their less-critical VMs - for instance, VM templates - both from ‘outside’ and from ‘inside’. The eG agent in this case can be configured to completely exclude such VMs from its monitoring purview. To achieve this, provide a comma-separated list of VMs to be excluded from monitoring in the exclude vms text box. Instead of VMs, VM name patterns can also be provided here in a comma-separated list. For example, your exclude vms specification can be: *xp,*lin*,win*,vista. Here, the * (asterisk) is used to denote leading and trailing spaces (as the case may be). By default, this parameter is set to none indicating that the eG agent obtains the inside and outside views of all VMs on a virtual host by default. By providing a comma-separated list of VMs/VM name patterns in the exclude vms text box, you can make sure the eG agent stops collecting ‘inside’ and ‘outside’ view metrics for a configured set of VMs.
  11. ignore vms inside view - Administrators of some high security VMware environments might not have permissions to internally monitor one/more VMs. The eG agent can be configured to not obtain the inside view of such ‘inaccessible’ VMs using the ignore vms inside view parameter. Against this parameter, you can provide a comma-separated list of VM names, or VM name patterns, for which the inside view need not be obtained. For instance, your ignore vms inside view specification can be: *xp,*lin*,win*,vista. Here, the * (asterisk) is used to denote leading and trailing spaces (as the case may be). By default, this parameter is set to none indicating that the eG agent obtains the inside view of all VMs on an ESX host by default.

    Note:

    While performing VM discovery, the eG agent will not discover the operating system of the VMs configured in the ignore vms inside view text box.

Measurements made by the test

Measurement Description Measurement Unit Interpretation

Availability of datastore for the VM:

Indicates whether/not this datastore is available.

Percent

While the value 0 indicates that the datastore is not available, the value 100 indicates that the datastore is currently available. If a datastore becomes unavailable, then VMs that are currently using that datastore could be rendered inaccessible to users.

Portion of datastore space used by VM:

Indicates the storage space on this datastore that is actually being used by this virtual machine.

MB

Comparing the value of this measure across VMs will enable you to quickly identify the VM that is consuming maximum datastore space.

Datastore space used by other files of the VM:

Indicates the percentage of space on this datastore that is being consumed by this VM.

Percent

If a datastore is experiencing a space crunch, then you can compare the value of this measure across VMs to identify which VM is responsible for it.

Datastore space used by other files of the VM:

Indicates the total space on this datastore that is being used by files such as configuration, suspend data, NVRAM, screenshots and others. This does not include Virtual Disks, snapshots or swap files.

MB

If a datastore is being rapidly drained of space, then, you can compare the value of the Other VM space and Space used measure for each VM, so as to quickly isolate what type of files associated with which VM are occupying too much space.

Space used by VM in datastore:

Indicates the percentage of space used on this datastore by other files.

Percent

If a datastore is being rapidly drained of space, then, you can compare the value of the Percent other VM space and Percent space used measures across VMs, so as to quickly isolate what type of files associated with which VM are occupying too much space.

Uncommitted space of VM in datastore:

Indicates the additional storage space potentially used by this virtual machine on this datastore.

MB

Additional space may be needed for example when lazily allocated disks grow, or storage for swap is allocated when powering on the virtual machine.

If the virtual machine is running off delta disks (for example because a snapshot was taken), then only the potential growth of the currently used delta-disks is considered.

Unshared space of VM in datastore:

Indicates the storage space, in bytes, occupied by the virtual machine on this datastore that is not shared with any other virtual machine.

MB

 

Provisioned space of VM in datastore:

Indicates the amount of space on this datastore that has been provisioned for this VM.

MB

This is typically the sum total of the disk space used by the VM and the uncommitted space for this VM on this datastore.

Number of virtual disks:

Indicates the number of virtual disks in this datastore.

Number

 

Swap file space:

Indicates the amount of space in this datastore that is occupied by the swap file of this VM.

MB

A swap file is created by the ESX/ESXi host when a virtual machine is powered on. If this file cannot be created, the virtual machine cannot power on. By default, the swap file is created in the same location as the virtual machine’s configuration file.

In the event of a space crunch, you may want to compare the values of the Swap file space, Virtual disk file space, and Snapshot file space measures to figure out which file is contributing to the space contention.

Swap file space usage:

Indicates the percentage of space in this datastore that is occupied by the swap file of this VM.

Percent

Snapshot file space:

Indicates the amount of space in this datastore that is used for storing a snapshot of this VM.

MB

A snapshot captures the entire state of the virtual machine at the time you take the snapshot. Snapshots are useful when you need to revert repeatedly to the same state but you do not want to create multiple virtual machines.

A snapshot includes the following information:

  1. Contents of the virtual machine’s memory
  2. Virtual machine settings
  3. State of all the virtual machine’s virtual disks

In the event of a space crunch, you may want to compare the values of the Swap file space, Virtual disk file space, and Snapshot file space measures to figure out which file is contributing to the space contention.

Snaphot file space usage:

Indicates the percentage of space that is used for creating a snapshot of this VM in this datastore.

Percent

Virtual disk file space:

Indicates the amount of space in this datastore that is occupied by the virtual disk file of this VM.

MB

A virtual machine uses a virtual hard disk to store its operating system, program files, and other data associated with its activities. A virtual disk is a large physical file, or a set of files, that can be copied, moved, archived, and backed up as easily as any other file. To store virtual disk files and manipulate the files, a host requires dedicated storage space.

In the event of a space crunch, you may want to compare the values of the Swap file space, Virtual disk file space, and Snapshot file space measures to figure out which file occupies the maximum space in a datastore.

Virtual disk file space usage:

Indicates the percentage of space available for the virtual disk of this VM in this datastore.

Percent

 

Is thin provisioned:

Indicates whether this datastore is thin provisioned or not.

Number

This measure reports either Yes or No while indicating whether this datastore is thin provisioned or not.

The numeric values that correspond to those states are as follows:

State Numeric Value

Yes

0

No

1

Note:

By default, this measure reports the above-mentioned states while indicating whether this datastore is thin provisioned or not. However, the graph of this measure will be represented using the corresponding numeric equivalents of the states as mentioned in the table above.

Percentage of saved space:

Indicates the percentage of space saved by this VM in this datastore.

Percent

 

Average write requests rate:

Indicates the average number of write commands issued per second to this datastore by this VM during the collection interval.

Commands/Sec

 

Average read requests rate:

Indicates the average number of read commands issued per second to this datastore by this VM during the collection interval.

Commands/Sec

 

Write latency:

Indicates the average amount of time taken for a write by this VM from the perspective of this datastore.

Secs

A high value indicates that the VM is taking too long to write to the datastore. Compare the value of this metric across VMs and datastores to know which VM registered the maximum write latency with respect to which datastore.

Read latency:

Indicates the average amount of time taken for a read by this VM from the perspective of this datastore.

Secs

A high value indicates that the VM is taking too long to read from the datastore.

Compare the value of this metric across VMs and datastores to know which VM registered the maximum read latency with respect to which datastore.

Read rate:

Indicates the rate at which data is read from this datastore.

MB/Sec

A high value is desired for these measures. A low value or a consistent dip in the value is indicative of an I/O latency.

Write rate:

Indicates the rate at which data is written to this datastore.

MB/Sec

Total latency:

Indicates the total amount of time taken to read from and write into this datastore from the perspective of guest operating system.

Secs

A high value or a consistent rise in the value of this measure is a cause for concern, as it indicates a current/potential I/O processing bottleneck with the datastore.

Throughput:

Indicates the rate at which the data is read from or written into this datastore.

 

MB/Sec

Ideally, the value of this measure should be high. A sudden or steady drop in this value could indicate a gradual deterioration in the performance of the datastore, probably owing to a processing bottleneck.

Total IOPS:

Indicates the total number of write commands issued and read commands issued per second to this datastore by this VM.

Commands/Sec