Citrix MCS Storage Driver - OS Test
Machine Creation Services (MCS) Storage Optimization (MCSIO), is a new feature within MCS provisioning. MCSIO reduces I/O load through a two-tier caching system. An in-memory cache, known as the “temporary memory cache,” is used as the first storage tier. If the in-memory cache fills up, subsequent writes will be cached using an additional disk attached to the provisioned machine as the second tier - this is known as the “temporary disk cache.” To achieve this, MCSIO provisioned machines have an additional MCSIO driver to intercept and manage IO operations.
For improved I/O performance, both the storage tiers should be adequately sized, so that the likelihood of writes directly reaching the system disk reduces considerably. If the caches are not sized right, then they may soon run out of space for writes, causing the driver to direct writes to the system disk. This in turn will reduce cache hits, increase direct disk accesses, and thus, significantly degrade I/O performance. To avoid this, administrators should continuously monitor the I/O load on the MCSIO driver, understand how the driver uses the in-memory and disk cache for managing these I/O operations, and make sure that the caches are sized right to support these operations. This is where the Citrix MCS Storage Driver - OS test helps!
This test auto-discovers the virtual machines on the target virtual server and, for each virtual machine, tracks the I/O requests to the driver and reports the rate at which the driver reads from or writes into each of the caches and the system disks in order to process these requests. This way, the test reveals whether/not the caches are doing a good job of preventing direct disk accesses. Additionally, the test also closely monitors how the memory in the in-memory cache and the disk space in the cached disk is utilized, and proactively alerts administrators to any potential resource crunch in the caches. This way, the test provides useful sizing pointers to administrators.
This test is disabled by default. To enable the test, go to the enable / disable tests page using the menu sequence : Agents -> Tests -> Enable/Disable, pick the desired Component type, set Performance as the Test type, choose the test from the disabled tests list, and click on the < button to move the test to the ENABLED TESTS list. Finally, click the Update button.
Target of the test :A VMware vSphere VDI
Agent deploying the test : A remote agent
Outputs of the test : One set of results for each virtual desktop on the VMware vSphere VDI server being monitored
Parameter | Description |
---|---|
Test Period |
How often should the test be executed |
Host |
The host for which the test is to be configured |
Port |
The port at which the HOSTlistens. By default, this is NULL. |
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 discovering the VMs on the target ESX server and collecting performance statistics from it. These monitoring/discovery methodologies and their corresponding configuration requirements have been discussed hereunder:
VM discovery using the vCenter in the target environment: By default, the eG agent connects to each ESX server and discovers the VMs executing on 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 perform guest discovery using the VM information already available in vCenter. 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 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 Terminate Sessions (from vCenter 4.1, this is called the View and stop 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 New User. 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. |
Confirm password |
Confirm the password by retyping it here. |
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. On the other hand, if the eG agent has been configured to use the VMPerl API or CLI for monitoring (i.e., if the ESX USER parameter is set to none), then the status of the SSL flag is irrelevant. Like the ESX sever, the vCenter is also SSL-enabled by default. If you have chosen to use the vCenter for monitoring all the ESX servers in your environment, then you have to set the SSL flag to Yes. |
Webport |
By default, in most virtualized environments, the 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 ESX server directly, the eG agent, by default, connects to port 443 of the ESX server to pull out metrics, and while monitoring a non-SSL-enabled ESX server, the eG agent connects to port 80. Similarly, while monitoring an 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 SSLflag. 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 ESX server or vCenter in your environment listens so that the eG agent communicates with that port. |
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 discover the guests on the ESX server via vCenter, then select the IP address of the vCenter host that you wish to use for guest discovery 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 USERand 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 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 and VM information - then set the VIRTUAL CENTER parameter to ‘none’. |
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. |
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. |
Ignore winnt |
By default, the eG agent does not support the inside view for VMs executing on Windows NT operating systems. Accordingly, the ignore winnt flag is set to Yes by default. |
Inside view using |
By default, this test obtains the “inside view” of VMs using the eG VM Agent. Accordingly, the Inside view using flag is set to eG VM Agent by default. The eG VM Agent is a piece of software, which should be installed on every VM on a hypervisor. Every time the eG agent runs this test, it uses the eG VM Agent to pull relevant 'inside view' metrics from each VM. Once the metrics are collected, the eG agent then communicates with each VM agent and pulls these metrics, without requiring administrator privileges. Refer to Configuring the Remote Agent to Obtain the Inside View of VMs for more details on the eG VM Agent. |
Domain, Admin User, and Admin Password, and Confirm Password |
By default, these parameters are set to none. This is because, by default, the eG agent collects 'inside view' metrics using the eG VM agent on each VM. Domain administrator privileges need not be granted to the eG agent if it uses this default approach to obtain the 'inside view' of Windows VMs. |
Report by User |
This flag is set to Yes by default. The value of this flag cannot be changed. This implies that the virtual machines in VDI environments will always be identified using the login name of the user. In other words, in VDI environments, this test will, by default, report measures for every username_on_virtualmachinename |
Report Powered OS |
This flag becomes relevant only if the REPORT BY USERflag is set to ‘Yes’ If the REPORT POWERED OS flag is set to Yes (which is the default setting), then this test will report measures for even those VMs that do not have any users logged in currently. Such guests will be identified by their virtualmachine name and not by the username_on_virtualmachinename. On the other hand, if the REPORT POWERED OS flag is set to No, then this test will not report measures for those VMs to which no users are logged in currently. |
DD Frequency |
Refers to the frequency with which detailed diagnosis measures are to be generated for this test. The default is 1:1. This indicates that, by default, detailed measures will be generated every time this test runs, and also every time the test detects a problem. You can modify this frequency, if you so desire. Also, if you intend to disable the detailed diagnosis capability for this test, you can do so by specifying none against DD FREQUENCY. |
Detailed Diagnosis |
To make diagnosis more efficient and accurate, eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option. The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:
|
Measurement | Description | Measurement Unit | Interpretation |
---|---|---|---|
Cache memory data reads |
Indicates the rate at which data is read from the in-memory cache. |
KB/Sec |
|
Cache memory data writes |
Indicates the rate at which data is written to the in-memory cache. |
KB/Sec |
A steady drop in the value of this measure could indicate a writing bottleneck. One of the reasons for this could be the lack of enough memory. Check the value of the Cache memory utilization measure to determine whether/not there is a memory crunch. |
Cache memory data reads and writes |
Indicates the rate at which data is written to and read from the in-memory cache. |
KB/Sec |
A steady drop in the value of this measure is indicative of an I/O bottleneck. |
Cache memory reads |
Indicates the rate at which read operations are performed on the in-memory cache. |
Reads/Sec |
|
Cache memory writes |
Indicates the rate at which write operations are performed on the in-memory cache. |
Writes/Sec |
|
Cache memory IOPS |
Indicates the rate at which read and write operations are performed on the in-memory cache. |
Operations/Sec |
|
Cache memory target size |
Indicates the amount of memory that the MCS storage driver will aim to use. |
MB |
|
Cache memory used |
Indicates the amount of memory that the driver has actually used. |
MB |
|
Cache memory free |
Indicates the amount of memory that is unused. |
MB |
|
Cache memory utilization |
Indicates the percentage of memory that the driver has utilized. |
Percent |
A value close to 100% is a cause for concern as it indicates that the in-memory cache is rapidly running out of memory. You may want to allocate more RAM to the cache to make sure that the writes do not spill over to the cache disk. |
Cache disk data reads |
Indicates the rate at which data is read from the cache disk. |
KB/Sec |
|
Cache disk data writes |
Indicates the rate at which data is written to the cache disk. |
KB/Sec |
A steady drop in the value of this measure could indicate a writing bottleneck. One of the reasons for this could be the lack of enough disk space in the cache disk. Check the value of the Cache disk utilization measure to determine whether/not there is a space crunch. |
Cache disk data reads and writes |
Indicates the rate at which data is written to and read from the cache disk. |
KB/Sec |
A steady drop in the value of this measure is indicative of an I/O bottleneck. |
Cache disk reads |
Indicates the rate at which read operations are performed on the cache disk. |
Reads/Sec |
|
Cache disk writes |
Indicates the rate at which write operations are performed on the cache disk. |
Writes/Sec |
|
Cache disk IOPS |
Indicates the rate at which read and write operations are performed on the cache disk. |
Operations/Sec |
|
Cache disk size |
Indicates the current size of the cache disk. |
MB |
|
Cache disk used |
Indicates the amount of space that the driver has used in the cache disk. |
MB |
|
Cache disk free |
Indicates the amount of space that is unused in the cache disk. |
MB |
|
Cache disk utilization |
Indicates the percentage of space used in the cache disk. |
Percent |
A value close to 100% is a cause for concern as it indicates that the cache disk is running out of disk space. You may want to expand the capacity of the cache disk to make sure that the writes do not spill over to the system disks. |
Storage driver read requests |
Indicates the number of read requests that were received by the MCS storage driver since boot. |
Number |
|
Storage driver write requests |
Indicates the number of write requests that were received by the MCS storage driver since boot. |
Number |
|
Storage driver read and write requests |
Indicates the number of read and write requests that were received by the MCS storage driver since boot. |
Number |
This is a good indicator of the I/O load on the driver. |
System disk data reads |
Indicates the rate at which data is read from the system disks. |
KB/Sec |
|
System disk data writes |
Indicates the rate at which data is written to the system disks. |
KB/Sec |
|
System disk data reads and writes |
Indicates the rate at which data is written to and read from the system disks. |
KB/Sec |
|
System disk reads |
Indicates the rate at which reads are performed from the system disks. |
Reads/Sec |
|
System disk writes |
Indicates the rate at which writes are performed into the system disks. |
Writes/Sec |
|
System disk IOPS |
Indicates the rate at which I/O operations are performed on system disks. |
Operations/Sec |
A zero value is desired for this measure. |