This blog contains experience gained over the years of implementing (and de-implementing) large scale IT applications/software.

With SAP LaMa you can auto-save on your Azure Managed Disk Costs

By now, most people know that after you’ve moved your SAP landscape to the cloud, you could save hosting costs by shutting down SAP system VMs when they are expected to not be used.
(There are caveats around this as it depends on whether you’re paying for reserved instances).

But did you know there’s also an extra saving that can be had in the cloud?

For SAP to support your SAP systems in Microsoft Azure, you must use Premium tier storage.
The reason for this is primarily because Premium tier storage comes with an SLA from Microsoft, which means you are expected to receive a certain level of performance from those disks.
However, you pay more for this SLA and the proposed performance. Which is quite correct, when you’re using the disk but what about when you’re not using the disk?

Right now, in the Azure “West Europe” region, a Premium tier P10 disk (SSD, 128GiB in size with 500 IOPS and 100MB/s throughput), will cost you £16.16 per month, excluding any deals and discounts (such as Azure Managed Disk Reservation).
The P10 is probably the work-horse of the majority of mid-sized server estates. Microsoft recommend a P10 as the Linux root disk for SUSE Linux based HANA database M-Series Azure VMs.

At the other end, the cost of a Standard tier E10 disk (SSD, 128GiB with 500 IOPS and 60MB/s throughput) is £7.16 per month, with the only performance difference being the throughput and the SLA:

So for the same size disk, although with lower throughput, we pay £9 per month less (55% less). I am going to say this saving is roughly 30 pence per day.

(There is one caveat and that is for standard SSD disks like the E10, you pay a transaction fee of 0.1 pence (£0.001) on the disk for every 10,000 256KiB I/O operations.
However, we will see that this transaction fee will not impact us and our saving, in a moment.)

Here’s how we can save money on this Premium managed disk.

In Microsoft Azure, you can change the disk tier from Premium to Standard, when the VM on which the disk is attached is shutdown (deallocated).
It’s simple, you just use the Azure Portal to change the disk configuration once the VM is shutdown.

While this is nice for just a couple of disks, this is not something you’re going to want to do on a regular basis.
Don’t forget, before you start the VM you need to switch the disk tier back to Premium (to retain your SAP support).
So for mass-changes, you may want to use PowerShell to adjust the disks before starting the VMs.
This itself could become a bit of a burden, since you now lose the ability to mass-power-on VMs from the Azure Portal completely.  You would need to use PowerShell all of the time, or setup an Azure based operation schedule (a.k.a. Power Automate – previously Microsoft Flow).

This is where SAP Landscape Manager (LaMa) really comes into its own.
With SAP LaMa, your BASIS team can:

  • Perform the start-up & shutdown of the SAP relevant VMs.
  • Perform the start-up & shutdown of the SAP systems on the VMs once they have been started (or the reverse).
  • Use the inbuilt scheduling capability of SAP LaMa to schedule the VM and SAP system operations (full automation of start-up and shutdown operations of the whole stack).

The security capabilities of Azure, coupled with SAP LaMa mean that the BASIS team can only perform specific VM related operations on the SAP VMs. Which gives the cloud Ops team peace of mind.

Now for the best bit.
To be able to save money on managed disk costs in Azure, the SAP BASIS administrator has to merely tick a tickbox in the SAP LaMa cloud provider settings, to “Change Storage Type to save costs”:

The next time the VM is de-allocated, SAP LaMa automatically changes the disk configuration in Azure, to a lower cost disk tier.
As we mentioned earlier, since the start/stop is controlled by SAP LaMa, it knows to switch the disk back to Premium tier during the start-up operation.

How simple is that!

As mentioned, there are some complications around any reservation payments for managed disk, so you need to understand what you’re paying for, before just enabling the tick-box!

Here are my very basic calcs for our P10/E10 disk combination example:

  • Weekends per year: 52
  • Saving per weekend: 60 pence
  • Total possible saving per year for 1 disk if it was unused every weekend: £31.20

Now let’s imagine that saving opportunity was applied across your 100 server estate, whereby every server had at least 1x P10 disk.
You can’t shutdown production, because it’s 24/7, but you don’t do development & testing round-the-clock and you have no international locations, so we are going to imagine our SAP estate is maybe 70% applicable to this saving opportunity. That’s 70 servers x £31.20 equals a saving of £2,184 per year on managed disk, by ticking a tickbox.

These are obviously just best guesses, but it shows how costs can build up and can also be reduced.

Happy ticking.

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