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Chapter 12. Working With Hosts
108
mysql> select id from cloud.host where name like '%h%';
4. This should return a single ID. Record the set of such IDs for these hosts.
5. Update the passwords for the host in the database. In this example, we change the passwords for
hosts with IDs 5, 10, and 12 to "password".
mysql> update cloud.host set password='password' where id=5 or id=10 or id=12;
12.9. Over-Provisioning and Service Offering Limits
(Supported for XenServer, KVM, and VMware)
CPU and memory (RAM) over-provisioning factors can be set for each cluster to change the number
of VMs that can run on each host in the cluster. This helps optimize the use of resources. By
increasing the over-provisioning ratio, more resource capacity will be used. If the ratio is set to 1, no
over-provisioning is done.
The administrator can also set global default over-provisioning ratios in the cpu.overprovisioning.factor
and mem.overprovisioning.factor global configuration variables. The default value of these variables is
1: over-provisioning is turned off by default.
Over-provisioning ratios are dynamically substituted in CloudPlatform's capacity calculations. For
example:
Capacity = 2 GB
Over-provisioning factor = 2
Capacity after over-provisioning = 4 GB
With this configuration, suppose you deploy 3 VMs of 1 GB each:
Used = 3 GB
Free = 1 GB
The administrator can specify a memory over-provisioning ratio, and can specify both CPU and
memory over-provisioning ratios on a per-cluster basis.
In any given cloud, the optimum number of VMs for each host is affected by such things as the
hypervisor, storage, and hardware configuration. These may be different for each cluster in the same
cloud. A single global over-provisioning setting can not provide the best utilization for all the different
clusters in the cloud. It has to be set for the lowest common denominator. The per-cluster setting
provides a finer granularity for better utilization of resources, no matter where the CloudPlatform
placement algorithm decides to place a VM.
The overprovisioning settings can be used along with dedicated resources (assigning a specific cluster
to an account) to effectively offer different levels of service to different accounts. For example, an
account paying for a more expensive level of service could be assigned to a dedicated cluster with an
over-provisioning ratio of 1, and a lower-paying account to a cluster with a ratio of 2.
When a new host is added to a cluster, CloudPlatform will assume the host has the capability to
perform the CPU and RAM over-provisioning which is configured for that cluster. It is up to the
administrator to be sure the host is actually suitable for the level of over-provisioning which has been
set.