Re: [Xen-API] Which API for Xen performance metrics

[Mike McClurg <mike.mcclurg@xxxxxxxxxx>]

On 10/18/2011 07:41 AM, Vikas Aggarwal wrote:
> Hi all,
>
> I am trying to determine which is the preferred API to get performance
> metrics for the Xen hypervisor AND also, what is the complete list of
> performance metrics that are available for the Xen hypervisor (v5.6 and
> newer) - trying to write a XenServer monitor in java.
First of all, please note that the Xen hypervisor is not the same thing 
as XenServer or XCP. Xen is a component of XenServer/XCP, much like the 
kernel of an operating system. Xen has it's own low-level APIs which are 
distinct from those of XCP or XenServer.
XCP is an open source clone of XenServer, and documentation referring to 
XenServer will also apply to XCP. The current version of XCP, XCP 1.1, 
is equivalent to XenServer 5.6 SP2. Both XCP and XenServer are complete 
virtualization management appliances, which come bundled with the Xen 
hypervisor and the XCP/XenServer XenAPI [1].
> I saw a posting in April asking about this and the xend API going away, and
> using XCP, but isn't there a non-XCP API which can give hypervisor metrics
> for "normal XenServer" ?
xend is the Xen daemon for the Xen hypervisor, but this is not installed 
in XCP/XenServer, so you won't be using that API.
> Lots of searching yielded
> http://www.jansipke.nl/getting-xenserver-vm-metrics-in-java  but it seems a
> bit weird to be using RRD for performance counters. There seem to be a lot
> of well defined performance metrics for VMware, but cannot find a clean
> solution for XenServer.
>
> Any definitive answer would be great since I cannot seem to find one.
Yes, XCP and XenServer use RRD to capture performance metrics. The page 
you found above gives a decent explanation of how to capture performance 
metrics in XCP/XenServer. Unfortunately, this aspect of XCP/XenServer is 
not very well documented.
The best documentation I've found so far is this [2] page, which 
explains XCP/XenServer's RRD API, and how to use the metrics. Hopefully 
this page will answer your questions.
Mike

[1] http://docs.vmd.citrix.com/XenServer/6.0.0/1.0/en_gb/api/
[2] http://community.citrix.com/display/xs/Using+XenServer+RRDs

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