Monitoring Large-scale Cloud Infrastructures with OpenNebulaSimon BouletOpenNebula ConsultantCo-founder of the Cloudnorth.com Projectsimon@nostalgeek.com

Goals

1. Show how to configure OpenNebula to achieve sub-1 minute monitoring interval

2. Demonstrate the use of OpenNebula in large-scale cloud infrastructures

3. Suggest enhancements to OpenNebula performance and monitoring

How Big Exactly is Large-scale?

How many hosts?1,000? 2,000? 10,000 VMs?

Monitoring in OpenNebula

● Detects when a VM or host changes status (Running, Stopped, etc.)

● Built-in metrics: CPU, memory and network usage

● You can add as many metrics as you like by customizing driver

● Can be used to perform various tasks (auto scaling, high-availability redeployment, etc.)

Don't Expect the Default Configuration to Perform Optimally

● Database: Use MySQL database backend, not the default SQLite

● Logs: Use Syslog log system, and disable debug logging (debug_level=1)

● Number of threads: Adjust the number of drivers threads (see -t option to your *MAD config options)

Use OpenNebula >= 4.0

Prior versions did monitoring in two phases:1. The IM Monitor action monitored Hosts2. The VMM Poll action monitored VMs

100 Hosts + 1,000 VMs * 15 seconds interval = 4,400 actions per minute

Since OpenNebula 4.0, the IM Monitor action is capable of returning the information of VMs running on the monitored host

Monitoring History

By default OpenNebula keeps 24h of monitoring history

15 seconds interval X 24h = 5760 records per VMAverage record size: 4KB23MB of monitoring history per VM

100 VM = 2.3GB10,000 VM = 230GB

HOST_MONITORING_EXPIRATION_TIME and VM_MONITORING_EXPIRATION_TIME config options

Monitoring History (continued)

● Reduce history to 30 minutes (1800 seconds)

● Use MySQL MEMORY storage engine for vm_monitoring and host_monitoring tables

It's OK to lose monitoring history when MySQL is restartedMost recent monitoring values are stored in VM templateSet MySQL max_heap_table_size large enough to hold all your monitoring history

Watch your Load Average

As of 4.2, the maximum number of simultaneous XML-RPC API connections is limited to 15Overloaded OpenNebula = Slow XML-RPC API response = API Limit / Timeout

● Reduce load at deployment time by adjusting number of VMs simultaneously deployed by scheduler

● Watch next release (4.4) forXML-RPC API concurrencyenhancements

Local Caching Nameserver

OpenNebula use DNS name for monitoring hosts (unless you named your hosts using their IP address instead of name)

● Use a local caching nameserver to speed up DNS lookup (such as dnsmasq).

Beware of SSH Transport

Most OpenNebula drivers (KVM, Xen, etc.) use SSH connections to perform actions

OK for deploying new VM, but expensive when doing VM monitoring

Meet Ganglia<< Ganglia is a scalable distributed system monitor tool for high-performance computing systems such as clusters and grids. >>- Wikipedia

OpenNebula has built-in support for GangliaBy default Ganglia and OpenNebula must run on the same machine

Set GANGLIA_HOST in /var/lib/one/remotes/im/ganglia.d/ganglia_probe and /var/lib/one/remotes/vmm/kvm/poll_ganglia

Meet Ganglia (continued)

Ganglia Driver Limitations

1. Currently only 1 Ganglia Collector is supported

2. Need to run script on each host to export OpenNebula-specific metric (OPENNEBULA_VMS_INFORMATION)

3. Ganglia as a maximum length of 1392 bytes for string metrics

Host sFlow<< The Host sFlow agent exports physical and virtual server performance metrics using the sFlow protocol. The agent provides scalable, multi-vendor, multi-OS performance monitoring with minimal impact on the systems being monitored.>>- http://host-sflow.sourceforge.net/

Exports a standard set of hypervisor and VM metricsOfficial support for Xen, KVM and Hyper-V, but uses Libvirt to gather metrics (and Libvirt has support LXC, OpenVZ, VMWare, etc.)

Host sFlow (continued)

Source: http://blog.sflow.com/2012/02/ganglia-33-released.html

Host sFlow (continued)

Sample MetricsHosts Metrics

VMs Metrics

Not currently supported in OpenNebula. Contact me if you're interested.

vnode_mem_total Hypervisor Total Memory

vnode_domains Hypervisor VM Count

<VM ID>.vcpu_state VM State (Running, Stopped, etc.)

<VM ID>.vmem_util VM Memory Utilization

<VM ID>.vdisk_free VM Free Disk Space

4,000 VMs at Sub-1 Minute Interval

OpenNebula 4.2 + xml-rpc patch (upcoming in 4.4)Experimental Host sFlow Driver1 OpenNebula Core (EC2 High-CPU XLarge instance)1 Sunstone Web Server (EC2 Standard Medium instance)1 Ganglia Collector (EC2 Standard Medium instance)100 Hosts (EC2 High-CPU Medium instances)~40 VMs per Host~4,000 VMs (OpenVZ)15 - 60 second monitoring interval

4,000 VMs at Sub-1 Minute Interval

4,000 VMs at Sub-1 Minute Interval

4,000 VMs at Sub-1 Minute Interval

Looking Forward

There’s room for optimizations

● The command line tools can get very slow when returning very large result sets (but not the API…)

● Distributed driver, for example using ZeroMQ for distributing tasks to multiple workers

● Investigate PoolSQL locks being held for long period and blocking other threads (discussed in bug #1818)

● Gather metrics about OpenNebula internals: locks wait, effective monitoring interval, memory footprints, etc.

● Investigate very large Sunstone memory usage

Thank you!

Questions?

“OpenNebula captured my interest for several technical reasons besides the fact that it is truly open. It's architecture is very elegant; it has C++ bones, ruby muscles and bash tendons. It's extensible and understandable. It has no peer as far as I can tell.”

Christopher Barry, Infrastructure Engineer, RJMetrics, September 2012

http://opennebula.org/users:testimonials