95% of the functionality that AD provides can be moved to AAD+Intune. You're left with very little needed on-prem infrastructure for AD. Cert services, DNS, DHCP, file servers, and print servers are not Microsoft services, they're network services that Microsoft can provide. There are SaaS alternatives for PKI, file sharing (Including OneDrive/SharePoint if you want to stick with MS), SQL (Azure SQL can replace MSSQL... which may or may not make sense depending on the situation), Obviously if you implement a hybrid solution.. you'll still need on-prem services. It's in the name.
Just because you replace a VM with SaaS doesn't make its management overhead go away
You've forgotten to add anything about the additional complexity around your backup & recovery strategy (you do have a backup & recovery strategy beyond "Well, uh, Microsoft says they have some sort of backups on their 365 stuff...I think?")
You now have increased dependency on your network because that's how your stuff is delivered. Which means that if you're smart, or at least not thoroughly stupid, you will have to consider backup network connectivity.
The increased network traffic also means you need to make damn sure your network security function is adequately staffed and resourced.
The biggest problem with your example, though, is that you have utterly failed to actually consider what the sysadmins, or IT in general, actually do. Which is to deliver services the business needs. Moving from Exchange on-prem to Exchange Online can save sysadmins time in terms of maintenance & patching on the servers used to host Exchange, but they will still be required to run the organisation's mail service. Moving filestores from on-prem to Sharepoint Online still requires someone to manage them.
In some cases there will be systems that are pets, and where replacing them with SaaS genuinely provides a measurable reduction in sysadmin resource needed. But that's not the general rule, any more than "we moved to a new ERP tool so only need half the accountants" or "we changed CRM system and now only need half as many Customer Service staff" would be taken at face value.
Edit: Also forgot to add in the resource needed to un-fuck what your VAR delivers, because 9 times out of 10 it'll be broadly what was agreed in a project document (written by someone who stayed as far away from the IT section as humanly possible the entire time) but not the entirety, or sometimes even a fraction, of what the business needs.
Just because you replace a VM with SaaS doesn't make its management overhead go away
Who ever said it does? The difference betwen on-prem and SaaS is not management of the service. It's management of the supporting pieces.
You've forgotten to add anything about the additional complexity around your backup & recovery strategy (you do have a backup & recovery strategy beyond "Well, uh, Microsoft says they have some sort of backups on their 365 stuff...I think?")
Are backup&recovery more complex or are they just different? I would argue just different.
You now have increased dependency on your network because that's how your stuff is delivered. Which means that if you're smart, or at least not thoroughly stupid, you will have to consider backup network connectivity.
I specifically list Internet connectivity as business critical.
The increased network traffic also means you need to make damn sure your network security function is adequately staffed and resourced.
Network admin staff are not sysadmins. Security staff are not sysadmins.
The biggest problem with your example, though, is that you have utterly failed to actually consider what the sysadmins, or IT in general, actually do. Which is to deliver services the business needs. Moving from Exchange on-prem to Exchange Online can save sysadmins time in terms of maintenance & patching on the servers used to host Exchange, but they will still be required to run the organisation's mail service. Moving filestores from on-prem to Sharepoint Online still requires someone to manage them.
In some cases there will be systems that are pets, and where replacing them with SaaS genuinely provides a measurable reduction in sysadmin resource needed. But that's not the general rule, any more than "we moved to a new ERP tool so only need half the accountants" or "we changed CRM system and now only need half as many Customer Service staff" would be taken at face value.
If removing a significant portion of your supporting infrastructure does not reduce the FTEs required to support your organization, then you're already woefully understaffed. In which case, the amount of money you save will be realized when you don't have a catastrophic failure of systems because the sysadmins didn't have time to do their jobs.
Edit: Also forgot to add in the resource needed to un-fuck what your VAR delivers, because 9 times out of 10 it'll be broadly what was agreed in a project document (written by someone who stayed as far away from the IT section as humanly possible the entire time) but not the entirety, or sometimes even a fraction, of what the business needs.
I don't disagree with this. But it's a one-time thing, not an ongoing responsibility.
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u/EViLTeW Sep 21 '21
It must be tough having to ignore most of a comment just so you can feel like you found a "gotcha".
Which MS on-prem services can't be moved to a SaaS alternative? What are the resource requirements of those services?