The Difference Between IBM Power Systems S922, S914, and S924

Richie Palma, Tech Solutions Consultant

For IBM i shops, IBM’s POWER9 scale-out family consists of three main server models.  To say these servers can “scale-out” is a massive understatement. At the end of the day we could talk about the enterprise POWER9 family all day but the large majority of IBM i clients are rocking the POWER9 Scale-Out servers. So, I am going to focus my attention in this article on the beautiful, scalable, and rock-solid servers in the POWER9 Scale-out family.

The first thing you need to know is what the model names themselves can tell you.  Let’s use S914 as an example.  The “S” stands for scale-out, the “9” stands for Power9, the “1” represents the number of sockets (In this case, a single socket), and the “4” which represents the number of rack U’s of physical space the server will take up.

You can see in the chart below the different models and correlation to the naming convention logic.  You will also see that each of the servers were given a little refresh with the release of the “G-model” servers.

Let’s dive into the individual server models and the options available for each.

9009-41G – S914

The Power9 S914 1 socket 4U system with options for 4, 6 or 8 cores. The 4 and 6 core options are 2.3 to 3.8GHz cores and the 8 core option is 2.8 to 3.8GHz cores. It comes with 8 full height PCIe Gen4 slots with one slot consumed for the required base LAN adapter. There are multiple backplane options available.

At this point, I am going to touch on the 4-core server and the 6/8-core options separately because the 4-core has some major differences that need to be acknowledged.

Let’s start with the 6/8-core models.

Both the 6/8-core S914 servers support up to 16 memory DIMMs, at either 16GB, 32GB, or 64GB per feature.  With 16x 64GB memory DIMM’s we can max the S914 out at 1TB of memory.  The 6/8-core options have multiple backplane options but for most IBM i shops running internal disk, the 18 drive backplane delivers big storage without the need for expansion drawers.

The 41G model with 6/8-cores also supports NVMe with a maximum of 4 NVMe U.2 drives in the storage backplane itself, and 7 card slots that can have NVMe adapter cards inserted.  This will provide extremely fast I/O performance, with quite a lot of storage capacity.  The 6/8-core servers both are P10 SW tier for IBM i shops.

Now let’s talk about the 4-core model

The 4 core provides the CPU performance and throughput for smaller IBM i shops that want to remain in the P05 SW tier, which carries a much lower cost for OS, LPP, and maintenance.  It is limited to 64GB of memory via 2 or 4 x 16GB or 2 x 32GB DIMMs.  The 4-core unit supports a maximum of 10 disk drives, but SSD’s are limited by size to a max size per unit of 387GB.  Alternatively, the 4-core unit can support a maximum of either two U.2 NVMe PCIe devices in place of the 10 SAS drives, or two NVMe adapters.  These NVMe adapters can be a max of 3.2TB each.

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9009-42G – S924

As you can see, the S924 looks a lot like the S914 and you would be 100% correct.  The S924 populates the second socket and additional PCIe slots that are actually visible when looking under the covers of the S914.

The S924 is a 1 or 2 socket 4U system that supports up to 24 cores. The core options are 8 or 16 (2nd socket activated) cores at 3.8 – 4.0 GHz, 10 or 20 (2nd socket activated) cores at 3.5 – 3.9 GHz, the brand new 11 or 22 (2nd socket activated) cores at 3.45 – 3.9 GHz, or 12 or 24 (2nd socket activated) cores at 3.4-3.9 GHz.

For memory, the S924 has 16 slots per socket for a maximum of 32. It supports 16GB, 32GB, 64GB and 128GB DIMMs providing for a maximum of 2TB per socket or a maximum total of 4TB for the system. With both sockets populated the S924 can support 11 full height PCIe Gen4 slots. One slot is for the required base LAN adapter.  As with the S914, there are multiple backplane options including the split backplane and NVME options.

9009-22G – S922

The S922 is a 1 or 2 socket 2U system that supports up to 22 cores. The S922 is capable of supporting one or two sockets each with 11 cores at 2.8-3.8 GHz, 10 cores at 2.9-3.8 GHz, or 8 cores at 3.4-3.9 GHz. For IBM i shops, the big advantage to the S922 is that it provides a two-socket 22 core server that is still in the P10 software tier, which means IBM i and other licensed software is priced in the much more approachable p10 tier level.  IBM i is only supported when running under VIOS and each IBM i partition is limited to 4 cores. There is also a 1 core model of the S922, which can run IBM i natively without VIOS, but is limited to 64GB Memory, 8 disk drives, and 25 users.

The S922 has 16 memory slots per socket for a total of 32 slots maximum. Just like the S924, it supports 16GB, 32GB, 64GB, and 128GB DIMMs providing for a maximum of 2TB per socket or a maximum total of 4TB for the system. With both sockets populated the S922 comes with 11 low profile PCIe Gen4 slots. One slot is for the required base LAN adapter. If only one socket is populated there are 8 slots of which two are CAPI capable.

With the release of the upgraded G-model servers, IBM finally delivered a replacement for the single-core S812 that offered an entry-level option for the smaller IBM i shops. Instead of building this on a dedicated server model, IBM is serving it up as an option under the S922 family.  It is a one socket server with a single core at 2.8 to 3.8GHz. The single-core option is a cost-effective system that runs IBM i natively (no VIO server) and has a maximum of 64GB of memory. It cannot be upgraded later to add cores or memory and it does not support I/O expansion drawers.

At the end of the day, it comes down to the amount of performance you need to run your business and these three servers with their many socket/core, memory, and storage offer both small and large IBM i shops a rock-solid environment to support their business-critical applications.

Below is a CPW chart that further represents the scalability of the scale-out family.

I hope you got some value from this article and please reach out to me or anyone on the iTech team with any questions you have.  We are always here to help.  Ready to buy, give us a call and we will design the perfect POWER9 system for you.

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