IBM Power L1124 (9856-42H)
The Linux-optimized sibling of the S1124: a high-throughput scale-out server for open-source databases and Red Hat OpenShift, with the same DCM processor ceiling as the S1124.
The 9856-42H is the machine type of the IBM Power L1124, the 4U Linux-first Power 11 system. It matches the 9824-42A S1124 on chassis, memory, storage and core count, and posts 25,718 CPW per core. The difference that decides whether you can buy it is a licensing cap, not a specification.
On the 9856-42H, IBM i and AIX are limited to 25 percent of activated cores. On a 60-core system that is 15 cores of IBM i, maximum, no matter what the hardware could do. That cap is the entire buying decision. Estates that are overwhelmingly Linux with a small IBM i remnant fit this machine type well and pay less for it. Anything else belongs on the S1124.
L1124 at a glance
Processor options
L1124 processor feature codes
| Feature Code | Cores | Clock Speed | CPW | rPerf |
|---|---|---|---|---|
| EP4C | 16-core | 3.4-4.2 GHz | 433,000 | Not published |
| EP4B | 24-core | 3.05-4.15 GHz | Not published | Not published |
| EP4J | 30-core | 2.8-3.95 GHz | Not published | 559 |
| EP4C | 32-core | 3.4-4.2 GHz | 823,000 | 1,117 |
| EP4B | 48-core | 3.05-4.15 GHz | 1,118,500 | 1,529 |
| EP4J | 60-core | 2.8-3.95 GHz | 1,345,900 | 1,737 |
Processor table verified against the IBM Power L1124 9856-42H product listing at Midland Information Systems.
IBM i and AIX on the L1124 remain capped at 25% of total activated cores, per Midland Information Systems' published licensing note for this machine type. Buyers planning primarily IBM i or AIX workloads should compare the S1124 instead.
IBM 9856-42H datasheet
IBM Power L1124 (9856-42H) published specifications
| Specification | Value |
|---|---|
| Machine type-model | 9856-42H |
| Generation | IBM Power 11 |
| Sockets | 2 |
| Maximum cores | 60 in the DCM configuration |
| Memory | 64 GB to 8 TB DDR5 across 32 DDIMM slots |
| Internal storage | 244.8 TB NVMe (16x 15.3 TB) or 102.4 TB (16x 6.4 TB) |
| PCIe | 4 direct slots, Gen4 x16 or Gen5 x8 mix |
| I/O expansion | 1 NED24 drawer and 2 Gen4 I/O drawers (24 slots each) |
| CPW per core | 25,718 |
| Operating system posture | Linux-first. IBM i and AIX limited to 25 percent of activated cores |
Figures are the published maximums for this machine type. A specific installed system is defined by its processor feature code and activated core count, not by the machine type alone.
How to confirm you have a 9856-42H
From IBM i
DSPSYSVAL QMODEL returns the model portion and DSPSYSVAL QPRCFEAT returns the processor feature code. Together those two values identify a 9856-42H build exactly, which is more than the L1124 name alone tells a vendor.
From AIX, Linux or VIOS
lsconf reports the machine type and model on the first lines of output. prtconf gives the same alongside processor implementation and clock speed.
From the HMC
Managed system properties shows the machine type-model and serial together, plus installed against activated cores. This is the view to screenshot when requesting a quote.
From the bezel
The 9856 prefix marks the Linux-focused L-series; the equivalent S1124 is 9824-42A. Both are 4U with sixteen NVMe bays, so the machine type on the label is the only reliable way to tell them apart.
Next steps for a 9856-42H
The feature codes sit alongside their S-series counterparts on the Power 11 CPU page, with the full listing at IBM Power L1124. If the IBM i share of the workload is above a quarter, price the 9824-42A S1124 instead.
Sources
- IBM Power 11 Scale-Out Servers Redbook ... IBM Redbooks
Reference Documents
Related
IBM Power S1124 (9824-42A)
A quad-socket-capable, high-performance 4U scale-out server offering up to 60 Power 11 cores and 8 TB of DDR5 memory, built for enterprises and regional data centers.
IBM Power L1122 (9856-22H)
The Linux-optimized sibling of the S1122: a dual-socket 2U server with the same hardware ceiling but licensed for Linux-first environments, with limited AIX/IBM i core use.
IBM Power S1112 (9242-21B / 9242-21T)
The entry point into the IBM Power 11 generation: a single-socket, half-width 2U rack or tower system built for branch, edge, and smaller IBM i, AIX, and Linux deployments.
IBM Power S1122 (9824-22A)
A dense, dual-socket 2U scale-out server offering up to 60 Power 11 cores and 4 TB of DDR5 memory, IBM's mainstream choice for growing IBM i, AIX, and Linux environments.
Frequently Asked
What are the IBM Power 11 model numbers?
There are seven current IBM Power 11 models: the entry S1112 (machine type 9242-21B rack, 9242-21T tower), the scale-out S1122 (9824-22A) and S1124 (9824-42A), the Linux-optimized L1122 (9856-22H) and L1124 (9856-42H), and the enterprise scale-up E1150 (9043-MRU) and flagship E1180 (9080-HEU). See our full Power 11 model directory for structured specs on each.
What is the difference between S-series and L-series Power 11 models?
S-series (S1112, S1122, S1124) and L-series (L1122, L1124) models share nearly identical hardware, but carry different machine-type licensing. L-series machines are Linux and Red Hat OpenShift-first, with IBM i and AIX capped at roughly 25% of activated cores. If your workload is primarily IBM i or AIX, choose the equivalent S-series model instead.
Can IBM i run on the Power L1122 or L1124?
Yes, but only on up to roughly 25% of the system's total activated cores ... the L-series machine-type licensing is built around Linux and OpenShift as the primary workload. If IBM i is your primary or majority workload, the equivalent S1122 or S1124 is almost always the better fit.