XenServer 7 has been launched, and following on from the recent blog post announcing the XenServer Health Check feature, I want to get into more detail about the main aspects of this feature. Chiefly, how a XenServer pool can be enrolled into Health Check, how the Health Check upload is performed and how the Health Check analysis results are made available to the XenServer users.
This is an opt-in feature, with enrollment done from XenCenter. There are a few settings required for the enrollment:
- Health Check upload schedule: the frequency, in weeks (defaulted to 2 weeks), day of the week and time when you prefer the Health Check report to be automatically uploaded to Citrix Insight Services (defaulted to a random day of the week and to a random time between 1AM and 5AM). This allows admins to schedule the Health Check uploads for different pools on different days of the week and at a time convenient to them.
- XenServer credentials: these are the credentials that the XenServer Health Check Service will use to connect to the XenServer pool in order to collect the Health Check report.
- Authentication with Citrix Insight Services (CIS): on enrollment into Health Check, XenCenter requires the user’s Citrix credentials in order to obtain an authentication token from CIS. This token is then used to obtain a series of other tokens used by the Health Check Service in order to upload the Health Check reports (the upload token) and by XenCenter to obtain the results of the CIS analysis on these reports (the diagnostic token).
The Citrix credentials are not saved by XenCenter or XenServer, only the upload and the diagnostic tokens are saved in XenServer.
By using this token system, the Citrix credentials are only required once, and users can also enrol multiple servers / pools into Health Check using an existing token, because XenCenter can detect a previous authentication and offer to reuse it.
The Health Check Service is installed by default with each installation on XenCenter 7.0, and is responsible for collecting the XenServer Health Check reports and uploading them to the Citrix Insight Services (CIS).
Once installed, it runs as a background service on the XenCenter machine, under the name Citrix XenServer Health Check Service.
Tip: In this model, with XenCenter facilitating the enrollment and the Health Check Service performing the upload, XenCenter does not need to stay open for the Health Check to function.
The Health Check Service periodically (every 30 minutes) connects to the pools enrolled in Health Check and checks if an upload is due. If that’s the case, then it collects the Health Check report and uploads it to the CIS (also including the XenCenter logs). This report is a pre-defined server status report – in the same format as the one that XenCenter is generating in the Server Status Report wizard – containing XenServer logs and configuration files that are used by the CIS to identify problems in the XenServer system. A list describing the content of this report can be found here.
If an upload fails, it will be retried weekly until it succeeds or until another scheduled upload succeeds.
XenCenter displays the status of the scheduled Health Check uploads as the date and time of the last successful upload (or the last failed upload if that is most recent).
Admins also have the option to do “on-demand” health checks, by requesting additional uploads for a pool already enrolled in Health Check. This upload is also performed by the Health Check service.
Tip: XenCenter and the Health Check Service can be installed on multiple machines that the IT admin uses to manage their XenServer pools. In this configuration any of these services can collect and upload the Health Check report for any of the pools managed on the respective machine. The Health Check Service uses a locking mechanism to ensure that only one service will process an upload for a given pool.
On the CIS side, there are more than one hundred plugins that analyse this report for Networking, Storage or Runtime errors, Security vulnerabilities, missing critical Hotfixes, etc. Each issue found by the CIS diagnostic plugins is given a severity ranging from low to severe.
Once a report is analysed by the CIS, XenCenter displays the number of issues found, their severity (highest severity among the issues found) as a Red-Amber-Green status and a link to the full analysis on the CIS website.
Following the link to the CIS analysis result, users can see more details for each issue, including a recommendation on how to fix the problem. This recommendation may also include a link to a KB article.
With the analysis results available in XenCenter and the CIS website, the loop is closed, the you can quickly check the state of your system in XenCenter from the same place where it all started by enrolling your XenServer pools into Health Check.
Try XenServer Health Check for yourself and see the added value it brings to supporting and maintaining your infrastructure!