Ovirt

Whats new in RHEV 3 ?

by

May be this is one of the question which I keep answering since rhev 3 release, so thought of blogging about it.. Instead of copy-paste, why can’t I point directly to http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Virtualization/3.0/html/Manager_Release_Notes/sect-whatsnew.html ?

Glossary of RHEV/Ovirt terms ( Data Center, Storage Domain, SPM , Cluster, Hypervisor, VDSM..etc)

by

Data Center (DC):

It is the logical entity which consists of different clusters .. Clusters are made by number of hypervisors.. You can have more than 1 cluster in a DC.

 

Cluster:

As mentioned Cluster built by group of hypervisors.. The cluster has to be defined for a particular ‘processor’ type. For ex: You can not mix INTEL and AMD  hypervisors in the same cluster as of now.

 

RHEL or RHEV- hypervisor :

Refer #https://humblec.com/difference-between-kvm-and-rhevovirt/

RHEV-M ( RHEV Manager) : 

You got the answer from above URL.

VDSM:

The service running on RHEL or RHEV-Hypervisor which talks to RHEV Manager . This service listens on port 54321.

rhevm or jboss service :

The main service running on RHEV manager..

STORAGE DOMAIN :

This is the shared storage in a RHEV setup where Virtual Machines are hosted.. There are different protocols supported in a RHEV environment to create a storage domain.. NFS/ISCSI/FC ..etc.. When you create a storage domain there is a volume group created ( in case of FC/ISCSI) with NFS it is a file ..

STORAGE POOL MANAGER:  ( SPM)

In simple terms, there should be one server who controls access to the common/shared storage .  The SPM server do this job. There should be only one SPM per DC.  Any of the active host can be elected as a SPM server..

 

I am putting  “.” Here..  Let me know if you need anything need to be expanded or explained..

 

Additional Info:

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Virtualization/3.0/html-single/Installation_Guide/index.html

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Virtualization/3.0/html/Technical_Reference_Guide/chap-Technical_Reference_Guide-Storage_Architecture.html

www.ovirt.org/wp-content/uploads/2011/11/ovirt-vdsm-storage.pdf

 

 

 

 

 

 

 

 

“Image Locked” status in ovirt/RHEV-M GUI

by

This is just an informational note :

 

As you know, it is possible to perform lots of operations on virtual machines through ovirt/rhev-m gui.. Before performing such operations, the VM storage has to be locked to avoid further damage/data corruption.. That said, all storage operations, such as create/delete VM/Template/Snapshot, will lock the VM image to perform the same. The storage operations (ex: snapshot ) depends the VM disk image size and the data on it. The time needed to perform these operations  vary.  So you may see “image locked” status on this time.. If the “VM” is continuing in “Image Locked” status for long time ( It depend on the operation) it could be something wrong with it, need to analyse further..

Should I use RHEL hypervisor or RHEV-Hypervisor ?

by

It is possible to use both ( RHEL and RHEV) hypervisors in an environment.. How-ever there are couple of things to consider.’1)  VDSM hooks are NOT supported with RHEV hypervisor, currently it is only supported with RHEL hypervisor. Refer below URL for more details on that. http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Virtualization/3.0/html/Administration_Guide/VDSM_Hooks.html 2) RHEV hypervisor is a dedicated appliance, it …

Read more

Difference between KVM and RHEV/OVIRT

by

Does the subject make any sense? hmmmm.. I don’t know. It is up to your decision because this is one of the questions which I get normally from people when they hear about Ovirt/RHEV ( RHEV is downstream/product offering from Red Hat based on upstream or community project called ovirt) or if you explain about it.

I will try to put these components in simple terms, if I fail, poke me with your comments.

KVM is a hypervisor, well yeah.. strictly speaking, I have to tell that, KVM makes/turns a Linux system as a hypervisor. Thus allows you to run virtual machines inside it. Sure, maybe you have heard that .. but then what is ‘libvirt’?

Libvirt is an API that allows you to talk with your hypervisor. The applications like ‘virt-manager‘ can take help from Libvirt to talk to the hypervisor ( ex: KVM). Thus manage virtual machine life cycle ie nothing but creation, managing and additional features like migration..etc.

From the above explanation, you may understand that, if you have a Linux kernel running in your system/machine KVM can host VMs ( virtual machines), and applications like ‘virt-manager’ can be used to administer it with the help of a library or API called `libvirt`.

Then, how Ovirt/RHEV is related to KVM? well, if you take a picture of an Ovirt/RHEV environment in my mind, it would look like this.

[Hypervisor 1] <——> [ Ovirt Manager/RHEV-Manager] <——-> [Hypervisor 2]

How these hypervisors are made? again KVM makes this hypervisor .. These hypervisors contact/talk to RHEV/Ovirt-Manager server. What is the communication channel between these hypervisors and Ovirt/RHEV-manager? It is a service called “vdsm” Ok.. sounds good. In that case, no “libvirt”? hmmm.. RHEV3 or the latest version of Ovirt makes use of Libvirt service. In RHEV3 context “vdsm”, trigger libvirt for VM life cycle operations. but still, vdsm is the communication agent between ovirt/rhev hypervisor and RHEV-Manager/Ovirt-Manager

RHEV hypervisor can be a RHEL system with KVM modules loaded. Otherwise a ‘live CD’ image called RHEV-H can act as a hypervisor. RHEV-H does not differ from a RHEL hypervisor in terms of KVM or vdsm. Just think RHEV-H as a live CD image with minimal size. It is a dedicated appliance and not supposed to run other applications like RHEL hypervisor.

We talked about Ovirt-Manager/RHEV-Manager Or Ovirt-M/RHEV-M, but what is it?

In simple terms, it is the managing server. Think of it in terms of an ‘administration’ server. In fact a GUI installed server 🙂

Finally, Do you want a ‘windows server’ in a RHEV environment? hmmm.. RHEV-Manager in RHEV 2 required it., but the latest version of RHEV-3/Ovirt does not require the ‘windows’ server. You can install RHEV3/ovirt Manager in a Linux system with a simple command,

[terminal]
#rhev-m setup
[/terminal]

I am stopping here.. but please feel free to ask your queries, if any. I would try to explain it in detail. This is a simple wrap up on KVM and RHEV/Ovirt…

ps# RHEV2 setup was not using ‘libvirt’ in RHEV hypervisor,

rhevm-manage-domains command to configure Active Directory or IPA in RHEV3

by

Unlike early rhev3 beta releases, the authentication server configuration ( Active Directory or IPA)  has been moved to seperate utility called ‘rhevm-manage-domains’. Installing rhev3 is that easy now.. It is as simple as that, firing ‘rhevm-setup’ command in a linux system.. Refer: rhevm-setup Once you ran above command, you have to configure authentication setup ( …

Read more

Network ports need to be opened in your firewall in context of RHEV

by

Below services or operations happens on below mentioned ports.. So make sure that, those are opened..
54321                                : vdsm

22                                       : ssh

5634 – 6166                        : guest console access ports

49152 – 49216                   : VM migration port range

32023                                : Spice  usb redirection

 

It is already mentioned here .

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Hypervisor_Deployment_Guide/chap-Deployment_Guide-Security_topics.html