RHEV-M+H FAQ

RHEV Manager and Hypervisor  Frequently Asked Questions

When a VM needs memory and there is no physical memory, will RHEV-H take memory from a running VM that isn't using all of their allocated memory?

 ATM RHEV don't leverage balloon right now . But it also depends on which OS you are using. Windows zeros all pages on boot, which KSM can later merge as they are all zeros. Linux consumes memory only when needed.

So for both, you can use memory unused by other guests. But the difference between "unused" and balloon is that:

unused literally means unused. Caches are considered used.

Balloon will take memory from the guest, which will force it to reduce amount of caching for example.

Is there an option in the hypervisor boot menu to re-install it ?  I don't  mean upgrade, i.e. all settings should be wiped and it should boot  into  the configuration menu ?

 linux firstboot 

 Can the rhev-h nodes boot from NFS? 

No.  NFS does not support SELinux attributes, and RHEVH requires SELinux for node security.  RHEVH can boot from FC or iSCSI SAN however, but not NFS. 

  Are the communications between rhev-m and the vdsm agents encrypted? if so, are the agents public keys stored somewhere on the rhev-m machine?

yes. No its not stored anywhere it  use PKI - trusted root approach.
Is internet access still required during the RHEV-M installation for validation of an SSL certificate ?

Starting 2.2 GA internet access is not required for RHEVM installation.

 Do RHEV & RHEV-M & VDI (Spice incl. plugin) support IPv6 ? 

There is an RFE for running the RHEV infrastructure on IPv6 in Bz 637547

https://bugzilla.redhat.com/show_bug.cgi?id=637547

 Is it Possible to Boot RHEV Hypervisor from SAN ?

yes, You can select multipath device in the RHEV-H first boot menu.  you just need to make sure that disk selected for RHEV-H installation is also selected as the boot disk in HBA BIOS.

if you're also planning on installing RHEL as a hypervisor, do not
forget to add the 'mpath' boot arg (if it applies to your SAN topology)

Note that "mpath" boot parameter[1] is for 5.4-2.1 only, in 5.5-2.2 multipath is started by default, so you just use storage_init=/dev/mapper/<wwid>

What is VDSM?

The Virtual Desktop Server Manager (VDSM) is a management module that serves as a Red Hat Enterprise Virtualization Manager (RHEV-M) agent on RHEV-Hypervisor (RHEV-H) or Red Hat Enterprise Linux hosts. 

 If a Hypervisor is placed in maintenance mode from RHEV Manager UI , is there anyway from the console of that system to tell that is is in maintenance mode ?

If so and by console you mean locally on the RHEL machine, then no, there is no way, as maintenance is purely a RHEVM internal logical state.

Is it possible to  add a rhev-h host via the RHEV Manager UI ?
No, You need to install RHEV-H on the host either after the first boot it will come for registration on RHEV Manager Hosts Tab, Register and Approve it.

So what is "Add Host" under Hosts Tab in RHEV Manager?
This button is only to add  RHEL Host for example if you are using RHEL5.4 or Later Operating System as Hypervisor. 

How to Create Bootable RHEV Hypervisors Media on USB Devices?

  http://documentation-stage.bne.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html-single/Hypervisor_Deployment_Guide/index.html#sect-Deployment_Guide-Preparing_a_RHEV_Hypervisor_USB_storage_device-Making_a_bootable_RHEV_Hypervisor_USB_storage_device 

Is it possible to Create a Virtual Machine Pools for Servers in RHEV?
No, Pools are a desktop only feature, are a nice to have feature to deploy a bunch of VDI VMs, not for proper server loads, so they are limited to the sparse/qcow2 disks.

Does RHEV Desktop Pools support virtual machine image with raw/preallocated disks?
No Because Pools are Only for Desktops and Not for Server Work Loads.

Does RHEV Supports PCI-Pass through ?

Not ATM, But you can Present  ISCSI or NFS disk to the virtual machines .

Is it  Possible to manage two administrator groups on the same RHEV-M that is  Each group have admin rights only on their group owned VMs?

In 2.2 only role based permissions are possible.

Is there is any Backup tools I can integrate with RHEV  ? 

Acronis has certified their product called "Advanced Backup & Recovery 10 Virtual Edition" for RHEV. You will find more information on the below URL.

http://www.acronis.com/enterprise/support/updates/changes.html?p=5404

Which third party tools does RHEV Supports for P2V or V2V?

Acronis  "Advanced Backup & Recovery 10 Virtual Edition" for RHEV.