IBM 9242-21B / 9242-21T
The 9242-21B and 9242-21T machine types are the rack and tower forms of the IBM Power S1112, the compact single-socket entry system IBM added to the Power 11 line in July 2026.
The 9242-21B is the rack form of the IBM Power S1112 and the 9242-21T is the deskside tower form of the same machine. They are the smallest Power 11 systems IBM sells, added to the line in July 2026, a year after the rest of the family. If you are looking up either number you are almost certainly pricing an entry IBM i refresh, because the 4-core build is the only Power 11 configuration that sits in software tier P05.
What makes this machine type worth understanding is the gap between what the platform holds and what IBM i can use on it. The chassis takes 512 GB of memory and 10 cores, but IBM i on the S1112 is bounded at 4 cores and 64 GB with mirrored internal storage. That is not a defect, it is the definition of the machine: a precise fit for a small IBM i footprint, and the wrong box the moment native IBM i growth becomes the real question.
IBM 9242-21B datasheet
IBM Power S1112 (9242-21B / 9242-21T) published specifications
| Specification | Value |
|---|---|
| Machine type-model | 9242-21B (rack) / 9242-21T (tower) |
| Generation | IBM Power 11 |
| Sockets | 1 |
| Maximum cores | 10 |
| Memory | 512 GB DDR5 DDIMM platform maximum. 256 GB usable for AIX, Linux and VIOS; 64 GB usable for IBM i at P05 |
| Internal storage | 12.8 TB NVMe U.2 across 4 slots |
| PCIe | 4 non-hot-plug PCIe Gen4 slots: 2x x16, 2x x8 |
| I/O expansion | Can use half of a Gen4 I/O expansion drawer when rack-mounted |
| Management | Embedded BMC plus a dedicated 1 GbE HMC port. Requires HMC v11 on a 7063-CR2 or vHMC |
| Operating systems | IBM i, AIX, Linux, VIOS |
| Software tier | P05 with the EJMT feature, P10 with the EJSV feature |
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.
Processor feature codes for the 9242-21B
S1112 processor options
| Feature | Cores | Clock (GHz) | CPW | rPerf ST / SMT2 / SMT4 / SMT8 | Tier |
|---|---|---|---|---|---|
| EJMT | 4 | 3.6 ... 4.0 | 117,300 | 39.9 / 81.8 / 119.9 / 148.8 | P05 |
| EJSV | 10 | 3.05 ... 4.0 | 116,500 | 95.4 / 185.6 / 247 / 298.7 | P10 |
Both options are entry single-chip modules. The EJMT build is the straight entry IBM i refresh configuration; the EJSV build is a much stronger mixed-workload and non-IBM-i platform in the same chassis, and it moves the whole system to P10.
The rack and tower numbers are not interchangeable in a parts lookup or a quote. 9242-21B is the half-width 2U rack chassis; 9242-21T is the deskside tower. The processor, memory and storage options are the same across both.
How to confirm you have a 9242-21B
From IBM i
DSPSYSVAL QMODEL returns the model portion and DSPSYSVAL QPRCFEAT returns the processor feature code. Together those two values identify a 9242-21B build exactly, which is more than the S1112 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
A 9242-21T is a floor-standing tower and a 9242-21B is a half-width 2U rack unit, so the two are impossible to confuse physically. The full machine type-model and serial are on the label at the front of the chassis.
Next steps for a 9242-21B or 9242-21T
Processor feature codes across the whole family are compared on the Power 11 CPU page, and the full model listing with CPW and rPerf detail is at IBM Power S1112. For configuration ceilings see the Power 11 specs page, for cost drivers see Power 11 pricing, and when you are ready to source one the quote checklist lists what a vendor needs from you.