I have an idea currently all the hosts in pool need to be powered up so that its manageable by Xen Orchestra, load balancing and/or High Availability (HA). For both business and home lab environments this can lead to high running costs, especially in electricity. This can be extremely wasteful and inefficient if the hosts don't have enough activity to be worth being powered on all of the time.

A power management plugin could be part of a piece of the puzzle to help manage these costs, by shutting down parts of a pool unless required.

In order to for this to occur yet still keep the pool in essence available there would be certain criteria as follows:-

• The host needs to have a configured remote power on setting assigned to it - Dell iDRAC, HPE iLO, WOL or IPMI etc
• The host's remote power on settings credentials need to be valid - will be checked
• The host needs to not have "don't allow power management shutdown" set for the host under XO possibly stored in XAPI or XO.
• The host must not be the current pool master
• The host must not be part of a configurable HA or LB buffer (with a minimum host number of 1, 2 or 3 - Vates and community can decide this)
• The host must not be required over a configurable period of time based on data from Xen Orchestra's metrics, load balancing and/or HA plugins or features

Hosts which meet the above criteria would be shutdown remotely by Xen Orchestra to be powered on and booted up when demand requires it, following automatically putting the host in maintenance mode. The powering on again would be performed through the remote power on settings configured in Xen Orchestra and/or as part of XAPI, with the host being taken out of maintenance mode automatically (if the host wasn't in maintenance mode manually - by the administrator or other appropriately role holding account).

The HA and/or LB plugins data wouldn't be taken into account if these plugins or features are unavailable (if running XOA) based on the edition utilised. Though if the edition of XOA is high enough or is done through Xen Orchestra from sources then this data will be taken into account as part of the eligibility criteria for the host.

For hosts in remote locations the necessary data would be encrypted and able to be carried by either site to site VPN and/or Xen Orchestra Proxy (XO Proxy).

Would being able to have Xen Orchestra being able to orchestrate the power states of the hosts help you with managing the costs of running your pools of servers?