2.1 Gdps -
The Gaussian filter defined in ISO 16610-21 (colloquially known as 2.1 GDPS) changed the game. Unlike 2RC filters, the Gaussian filter has zero phase shift. It uses a weighted average based on the normal distribution (the Gaussian bell curve) to remove waviness while preserving the true shape of primary surface features.
Key characteristics of the 2.1 GDPS standard:
For IBM i partitions, the hallmark of 2.1 GDPS is HyperSwap. Historically, if a primary storage volume failed, the system required an IPL (Initial Program Load). With HyperSwap, the IBM i operating system (via the DS8000 Multipath Driver) instantly redirects I/O to the secondary copy. In a 2.1 environment, HyperSwap is triggered automatically when GDPS detects a storage path failure, without disrupting active jobs. 2.1 gdps
Major OEMs (Automotive: VW, Tesla; Aerospace: Boeing, Airbus) are now updating their GEOMETRIC PRODUCT SPECIFICATION (GPS) standards to ISO 16610-21. If your supplier quality report does not mention "Filter: Gaussian (2.1)," you will likely fail the PPAP (Production Part Approval Process).
There are three persistent myths surrounding the 2.1 standard: The Gaussian filter defined in ISO 16610-21 (colloquially
Myth 1: It works with any storage.
False. 2.1 GDPS requires DS8880 or DS8900 series. It will not work with IBM FlashSystem (unless using SVC-based Metro Mirror, which is a different, non-2.1 architecture) or third-party arrays like Dell EMC or NetApp.
Myth 2: It replaces PowerHA (IBM i HA).
False. PowerHA manages application-level restarts and logical replication. 2.1 GDPS manages storage block-level consistency. In a mature environment, you run both: GDPS for site failover, PowerHA for LPAR failure within a site. Key characteristics of the 2
Myth 3: It requires dedicated fiber between sites.
Partially true. Metro Mirror (synchronous) requires low-latency dark fiber or DWDM (typically 10km to 25km). However, the 2.1 specification allows for "stretched cluster" over IP using FCIP, though performance will degrade.
