Tags

User Tags

You can create a user tag on a host by using resourceType=HostVO. For example,
CreateUserTag tag=largeMemoryHost resourceUuid=0a9f95a659444848846b5118e15bff32 resourceType=HostVO

System Tags

Host Capacity Reservation

You can use system tags to reserve a portion of memory on hosts for system software.

ZStack provides various system tags and global settings to realize fine-grained memory reservation policies.
  • Hypervisor Global Level

    If you do not have settings with other levels, you can apply the global level :ref:`kvm.reservedMemory` to all KVM hosts.

  • Zone Level

    For information about the zone level, see zone host::reservedMemory. If you do not have settings of other levels, you can apply the zone level to all hosts in the zone. This value will override the global level.

  • Cluster Level

    For information about the cluster level, see cluster host::reservedMemory. If you do not have settings of other levels, you can apply the cluster level to all hosts in the cluster. This value will override the zone level and global level.

  • Host Level
    Tag Description Example Starting Version
    reservedMemory::{capacity} The reserved memory on the host. reservedMemory::1G 0.6

    The host level can override all the above levels.

For example, assume that you have three KVM hosts, namely zone->cluster1->{host1, host2, host3}:
  • By default, the memory reservation for the three hosts is controlled by the global setting :ref:`kvm.reservedMemory` with the default value 512M.
  • If you create a system tag host::reservedMemory::1G on zone1, the memory reservation of all the three hosts will be changed to 1G.
  • If you create a system tag host::reservedMemory::2G on cluster1, the memory reservation of all the three hosts will be changed to 2G.
  • If you create a system tag reservedMemory::3G on host1, the memory reservation on host1 will be changed to 3G, but still 2G on both host2 and host3.
Host Metadata Information
Tag Description Example Starting Version
capability:liveSnapshot If this tag exists, the hypervisor of the host will support live volume snapshot. capability:liveSnapshot 0.6
os::distribution::{distribution} The operating system provider of the host. os::distribution::Ubuntu 0.6
os::release::{release} The operating system release version of the host. os::release::trusty 0.6
os::version::{version} The operating system version of the host. os::version::14.04 0.6
hostCpuModelName::{hostCpuModelName} The CPU model of the host. hostCpuModelName::Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz 3.1.0
systemProductName::{systemProductName} The server model. systemProductName::ProLiant DL388 Gen9 3.1.0
cpuGHz::{cpuGHz} The CPU clock speed of the host. Unit: GHz.
Note: Round 2 decimal places for this tag.
 cpuGHz::2.20 3.1.0
Note:
Statements on the following three system tags: hostCpuModelName::{hostCpuModelName}, hostCpuModelName::{hostCpuModelName}, and cpuGHz::{cpuGHz}.
  • These three system tags belong to the HostVO. You can obtain these tags by using the original API QuerySystemTag. In addition, you can obtain specified system tags by using the fuzzy search ~=.
  • Cluster and KVM Host have defined the following two system tags: clusterCpuModelName::{clusterCpuModelName} and cpuModelName::{cpuModelName} (such as cpuModelName::Broadwell) to be used by libvirt in migration scenario or others. Exercise caution that both the system tags are different from hostCpuModelName::{hostCpuModelName}.
KVM Host Metadata Information
Tag Example Example Starting Version
qemu-img::version::{version} The qemu-img version. qemu-img::version::2.0.0 0.6
libvirt::version::{version} The libvirt version. libvirt::version::1.2.2 0.6
hvm::{flag} The host hardware virtualization flag.
  • vmx: the Intel CPU.
  • svm: the AMD CPU.
 hvm::vmx 0.6
cpuModelName::{cpuModelName} The CPU model of the host. cpuModelName::Broadwell 0.6