My train of thought is still rolling. I think the usual virtualization setups both in Enterprise and hosting environments have stopped short of where they should be.
I’ll go as far as saying
- On-Demand provisioning is stupid (creates massive process and labor overheads)
- On-Demand provisioning is unnecessary (if centralized management is in place)
- NPIV actually proves I’m right (if you think it through)
This is what the announcement said for the last station:
- VM as container
- Create all VMs right away
- Including the “outer rim”, i.e. firewall rules, mac address, SAN zoning
- Select storage arrays based on space / performance parameters so your SAN can scale out (instead of looking beautiful centralized and symmetrical on the paper)
- Prepare VLANs and VPN access already
- No need to actually allocate / activate things yet
- Create Nagios, Backup config for all VMs. Just turn off their checks / backup runs.
Have a pool of VMs ready for assignment
- Yes, you can thin provision them
- But don’t do it on everything or you’ll see your performance go to hell
- These have OS installed and are waiting for policy updates (that will customize them as needed)
When a customer books the VM
- Automatically select a pooled or prepared VM for him
- No VM provisioning should be left to be done
- Activate the customer dependent parts of the policy
- If not using a pool VM, boot up into the OS installer and then let the policy do its work
- The policy should now also enable the infrastructure items (Nagios, Backups, OS Installation)
- Storage assignment as per customers choice
- Extra IP / VLAN / VPN assignment as per customers choice (from a pool
most people get that last one right, some don’t. I know one guy who hacked his automated VLAN/IP pool allocation system within a day with the rest of his customer panel, and I’ve seen (multiple) places where they use excel files to manage IP addresses. And some (also, multiple ones) that will actually have multiple out-of-sync systems for managing the same IP.
This is where I think the issue with on-demand arises. If your processes have issues, you’re making them worse this way. Because you will be having changes of the “Excel management” tool (in fact: all changes related to phasing in a new system) each time, one-by-one for each VM. It won’t scale like an assembly chain because you don’t have dedicated people doing the exact same thing all day. Instead you get the typical context-switch behaviour and insane overhead of constantly distracted admins doing manual labor (an automated bulk change on 10000 VMs will take them only 1-10 times of a manual change of 1 VM).
if “done right” you’ll plan and run all your assignments in the start and get a higher quality result, too.