DaanHoogland commented on a change in pull request #85: [WIP] Backup & Recovery Doc Guide URL: https://github.com/apache/cloudstack-documentation/pull/85#discussion_r386387670
########## File path: source/adminguide/virtual_machines.rst ########## @@ -268,296 +247,53 @@ Once a VM instance is created, you can stop, restart, or delete it as needed. In the CloudStack UI, click Instances, select the VM, and use the Stop, Start, Reboot, and Destroy buttons. -When starting a VM, admin users have the option to specify a pod, cluster, or host. - - -Assigning VMs to Hosts ----------------------- - -At any point in time, each virtual machine instance is running on a -single host. How does CloudStack determine which host to place a VM on? -There are several ways: - -- Automatic default host allocation. CloudStack can automatically pick - the most appropriate host to run each virtual machine. - -- Instance type preferences. CloudStack administrators can specify that - certain hosts should have a preference for particular types of guest - instances. For example, an administrator could state that a host - should have a preference to run Windows guests. The default host - allocator will attempt to place guests of that OS type on such hosts - first. If no such host is available, the allocator will place the - instance wherever there is sufficient physical capacity. - -- Vertical and horizontal allocation. Vertical allocation consumes all - the resources of a given host before allocating any guests on a - second host. This reduces power consumption in the cloud. Horizontal - allocation places a guest on each host in a round-robin fashion. This - may yield better performance to the guests in some cases. - -- Admin users preferences. Administrators have the option to specify a - pod, cluster, or host to run the VM in. CloudStack will then select - a host within the given infrastructure. - -- End user preferences. Users can not control exactly which host will - run a given VM instance, but they can specify a zone for the VM. - CloudStack is then restricted to allocating the VM only to one of the - hosts in that zone. - -- Host tags. The administrator can assign tags to hosts. These tags can - be used to specify which host a VM should use. The CloudStack - administrator decides whether to define host tags, then create a - service offering using those tags and offer it to the user. - -- Affinity groups. By defining affinity groups and assigning VMs to - them, the user or administrator can influence (but not dictate) which - VMs should run on separate hosts. This feature is to let users - specify that certain VMs won't be on the same host. - -- CloudStack also provides a pluggable interface for adding new - allocators. These custom allocators can provide any policy the - administrator desires. +A stop will attempt to gracefully shut down the operating system, via +an ACPI 'stop' command which is similar to pressing the soft power switch +on a physical server. If the operating system cannot be stopped, it will +be forcefully terminated. This has the same effect as pulling out the power +cord from a physical machine. +A reboot should not be considered as a stop followed by a start. In CloudStack, +a start command reconfigures the virtual machine to the stored parameters in +CloudStack's database. The reboot process does not do this. -Affinity Groups -~~~~~~~~~~~~~~~ - -By defining affinity groups and assigning VMs to them, the user or -administrator can influence (but not dictate) which VMs should run on -separate hosts. This feature is to let users specify that VMs with the -same “host anti-affinity” type won’t be on the same host. This serves to -increase fault tolerance. If a host fails, another VM offering the same -service (for example, hosting the user's website) is still up and -running on another host. - -The scope of an affinity group is per user account. - - -Creating a New Affinity Group -''''''''''''''''''''''''''''' - -To add an affinity group: - -#. Log in to the CloudStack UI as an administrator or user. - -#. In the left navigation bar, click Affinity Groups. - -#. Click Add affinity group. In the dialog box, fill in the following - fields: - - - Name. Give the group a name. - - - Description. Any desired text to tell more about the purpose of - the group. - - - Type. The only supported type shipped with CloudStack is Host - Anti-Affinity. This indicates that the VMs in this group should - avoid being placed on the same host with each other. If you see - other types in this list, it means that your installation of - CloudStack has been extended with customized affinity group - plugins. - - -Assign a New VM to an Affinity Group -'''''''''''''''''''''''''''''''''''' - -To assign a new VM to an affinity group: - -- Create the VM as usual, as described in `“Creating - VMs” <virtual_machines.html#creating-vms>`_. In the Add Instance - wizard, there is a new Affinity tab where you can select the - affinity group. - - -Change Affinity Group for an Existing VM -'''''''''''''''''''''''''''''''''''''''' - -To assign an existing VM to an affinity group: - -#. Log in to the CloudStack UI as an administrator or user. - -#. In the left navigation bar, click Instances. - -#. Click the name of the VM you want to work with. - -#. Stop the VM by clicking the Stop button. - -#. Click the Change Affinity button. |change-affinity-button.png| - - -View Members of an Affinity Group -''''''''''''''''''''''''''''''''' - -To see which VMs are currently assigned to a particular affinity group: - -#. In the left navigation bar, click Affinity Groups. - -#. Click the name of the group you are interested in. - -#. Click View Instances. The members of the group are listed. - - From here, you can click the name of any VM in the list to access all - its details and controls. - - -Delete an Affinity Group -'''''''''''''''''''''''' - -To delete an affinity group: - -#. In the left navigation bar, click Affinity Groups. - -#. Click the name of the group you are interested in. - -#. Click Delete. - - Any VM that is a member of the affinity group will be disassociated - from the group. The former group members will continue to run - normally on the current hosts, but if the VM is restarted, it will no - longer follow the host allocation rules from its former affinity - group. +When starting a VM, admin users have the option to specify a pod, cluster, or host. -Virtual Machine Snapshots +Deleting VMs ------------------------- -(Supported on VMware, XenServer and KVM (NFS only)) - -In addition to the existing CloudStack ability to snapshot individual VM -volumes, you can take a VM snapshot to preserve all the VM's data -volumes as well as (optionally) its CPU/memory state. This is useful for -quick restore of a VM. For example, you can snapshot a VM, then make -changes such as software upgrades. If anything goes wrong, simply -restore the VM to its previous state using the previously saved VM -snapshot. - -The snapshot is created using the hypervisor's native snapshot facility. -The VM snapshot includes not only the data volumes, but optionally also -whether the VM is running or turned off (CPU state) and the memory -contents. The snapshot is stored in CloudStack's primary storage. - -VM snapshots can have a parent/child relationship. Each successive -snapshot of the same VM is the child of the snapshot that came before -it. Each time you take an additional snapshot of the same VM, it saves -only the differences between the current state of the VM and the state -stored in the most recent previous snapshot. The previous snapshot -becomes a parent, and the new snapshot is its child. It is possible to -create a long chain of these parent/child snapshots, which amount to a -"redo" record leading from the current state of the VM back to the -original. - -After VM snapshots are created, they can be tagged with a key/value pair, -like many other resources in CloudStack. - -KVM supports VM snapshots when using NFS shared storage. If raw block storage -is used (i.e. Ceph), then VM snapshots are not possible, since there is no possibility -to write RAM memory content anywhere. - -If you need more information about VM snapshots on VMware, check out the -VMware documentation and the VMware Knowledge Base, especially -`Understanding virtual machine snapshots -<http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&externalId=1015180>`_. - - -Limitations on VM Snapshots -~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -- If a VM has some stored snapshots, you can't attach new volume to the - VM or delete any existing volumes. If you change the volumes on the - VM, it would become impossible to restore the VM snapshot which was - created with the previous volume structure. If you want to attach a - volume to such a VM, first delete its snapshots. - -- VM snapshots which include both data volumes and memory can't be kept - if you change the VM's service offering. Any existing VM snapshots of - this type will be discarded. - -- You can't make a VM snapshot at the same time as you are taking a - volume snapshot. - -- You should use only CloudStack to create VM snapshots on hosts - managed by CloudStack. Any snapshots that you make directly on the - hypervisor will not be tracked in CloudStack. - - -Configuring VM Snapshots -~~~~~~~~~~~~~~~~~~~~~~~~ - -The cloud administrator can use global configuration variables to -control the behavior of VM snapshots. To set these variables, go through -the Global Settings area of the CloudStack UI. - -.. cssclass:: table-striped table-bordered table-hover - -====================== ======================== -Configuration Description Type -====================== ======================== -vmsnapshots.max The maximum number of VM snapshots that can be saved for any given virtual machine in the cloud. The total possible number of VM snapshots in the cloud is (number of VMs) \* vmsnapshots.max. If the number of snapshots for any VM ever hits the maximum, the older ones are removed by the snapshot expunge job -vmsnapshot.create.wait Number of seconds to wait for a snapshot job to succeed before declaring failure and issuing an error. -====================== ======================== - - -Using VM Snapshots -~~~~~~~~~~~~~~~~~~ - -To create a VM snapshot using the CloudStack UI: - -#. Log in to the CloudStack UI as a user or administrator. - -#. Click Instances. - -#. Click the name of the VM you want to snapshot. - -#. Click the Take VM Snapshot button. |VMSnapshotButton.png| - - .. note:: - If a snapshot is already in progress, then clicking this button - will have no effect. - -#. Provide a name and description. These will be displayed in the VM - Snapshots list. - -#. (For running VMs only) If you want to include the VM's memory in the - snapshot, click the Memory checkbox. This saves the CPU and memory - state of the virtual machine. If you don't check this box, then only - the current state of the VM disk is saved. Checking this box makes - the snapshot take longer. - -#. Quiesce VM: check this box if you want to quiesce the file system on - the VM before taking the snapshot. Not supported on XenServer when - used with CloudStack-provided primary storage. - - When this option is used with CloudStack-provided primary storage, - the quiesce operation is performed by the underlying hypervisor - (VMware is supported). When used with another primary storage - vendor's plugin, the quiesce operation is provided according to the - vendor's implementation. - -#. Click OK. +Users can delete their own virtual machines. A running virtual machine +will be abruptly stopped before it is deleted. Administrators can delete +any virtual machines. -To delete a snapshot or restore a VM to the state saved in a particular -snapshot: +To delete a virtual machine: -#. Navigate to the VM as described in the earlier steps. +#. Log in to the CloudStack UI as a user or admin. -#. Click View VM Snapshots. +#. In the left navigation, click Instances. -#. In the list of snapshots, click the name of the snapshot you want to - work with. +#. Choose the VM that you want to delete. -#. Depending on what you want to do: +#. Click the Destroy Instance button. |Destroyinstance.png| - To delete the snapshot, click the Delete button. |delete-button.png| +#. Optionally both expunging and the deletion of any attached volumes can be enabled. - To revert to the snapshot, click the Revert button. |revert-vm.png| +When a virtual machine is **destroyed**, it can no longer be seen by the end user, +however, it can be seen (and recovered) by a root admin. In this state it still +consumes logical resources. Global settings control the maximum time from a VM +being destroyed, to the physical disks being removed. When the VM and its rooot disk +have been deleted, the VM is said to have been expunged. -.. note:: - VM snapshots are deleted automatically when a VM is destroyed. You don't - have to manually delete the snapshots in this case. +Once a virtual machine is **expunged**, it cannot be recovered. All the +resources used by the virtual machine will be reclaimed by the system, +This includes the virtual machine’s IP address. +Managing Virtual Machines +========================= Changing the VM Name, OS, or Group ----------------------------------- +------------------------------------- Review comment: over-underlining ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
