This week’s blog was written by Nancy Uthke-Schmucki, with assistance from Kris Whitney. Nancy is the IBM i Business Architect covering IBM i I/O Strategy and Architecture. Kris is a software developer on the IBM i team who works on virtual I/O and SAN development. Thanks, Nancy and Kris!
I want to tell you about a recently announced enhancement to IBM i 7.1 that allows you to natively attach entry-level external storage even to a Power Systems Express Model 710 or 720. Some of the supported configurations do not require a switch. This gives you a low-cost entry point into an external storage configuration that is a building block for some of the newer Power Systems and IBM i technologies, and gives an option for adding additional storage to the Power Systems Express systems that cannot attach an additional I/O drawer.
Before I continue with more details, let me review some terms to help you better understand this announcement.
First, you need to know that there are three types of I/O attachment to IBM i partitions: native attach, native attach with iVirtualization, and Virtual I/O Server (VIOS) attach.
1. Native attach - IBM i owns and uses the adapter to attach storage without the need for VIOS:
In this diagram there are two IBM i partitions on a system. Each of them has a native attach configuration for a set of disk storage. Each IBM i partition owns the adapter configuration and service, and has the use of the adapter and storage devices to which it is natively attached.
2. Native attach with iVirtualization - One IBM i partition has a native attachment and therefore owns and uses the adapter and storage without the need for VIOS, and other IBM i partitions can also be part of an iVirtualization configuration to use the storage as virtual clients:
In this diagram the first IBM i partition has a native attachment to a set of disk storage. The other two IBM i partitions are configured as virtual clients of the storage natively attached to the first partition. The first partition owns the adapter configuration and service, and has the use of the adapter and storage devices. The other two partitions are virtual clients that can use that same physical adapter to access part of the disk storage to which the adapter is attached. In essence, the partitions are sharing the adapter simultaneously, but each partition is configured to have sole access to a portion of the storage to which the adapter is connected.
3. VIOS attach - VIOS owns the adapter and other Power partitions can use the adapter and storage as virtual clients.
In this diagram the first partition is a VIOS partition that has the attachment to a set of disk storage. The other three partitions are one of each of the Power Operating System types that are configured as virtual clients of the storage attached to the VIOS partition. The VIOS partition owns the configuration and service of the adapter since it has the native attachment. The other three partitions are virtual clients that can use the same physical adapter to access part of the disk storage to which the VIOS partition is attached. In essence, the partitions are sharing the adapter simultaneously, but each partition is configured to have sole access to a portion of the storage to which the adapter is connected.
The second set of terms I’d like to review is “fabric attach” vs. “direct attach.” For any of the three types of configurations described above -- native attach, native attach with iVirtualization, and VIOS attach -- the system may or may not have a switch between the adapter and the disk storage. Fabric attach means that the configuration contains a switch, which gives flexibility to attach the disk storage to multiple systems. Direct attach means that the adapter port is directly connected to a port on the storage resource without the use of a switch. A direct attach configuration is therefore lower cost because it does not have the switch hardware.
Now on to the details of the May 28th announcement...
Back in February, IBM i announced additional support for VIOS attachment for fabric attach configurations that include IBM SAN Volume Controller (SVC) and IBM Storwize V7000, IBM Storwize V3700, and IBM Storwize V3500 Storage Systems. Although that February announcement provides better virtualization configurations for the entry and midsized external storage systems, they still required VIOS and switches, which are an additional level of complexity and cost that may not be acceptable for all IBM i customers. At the same time, many newer technologies such as FlashCopy, PowerHA for i, and VIOS advanced functions such as Suspend/Resume and Live Partition Mobility all require external storage configurations. Some customers are indeed looking for a smaller first step on the road to make use of these newer technologies.
Now the May announcement gives that smaller first step with additional options of creating configurations for IBM i that have native attachment to that same set of storage systems, thereby removing the need for VIOS. This native attachment support includes all POWER7 and POWER7+ rack systems that support IBM i, namely model numbers 710, 720, 730, 740, 750, 760, 770, 780 and 795. Load source support is included, as is enablement for the full use of PowerHA functions. As with all native attachment options for disk storage, having native attachment means that iVirtualization configurations are also supported.
IBM i 7.1 Technology Refresh PTF Group Level 6, along with permanently applied PTFs MF56600, MF56753 and MF56854 are needed for the IBM i partition. Resave level RS-710-H is also available and includes all those PTFs. You also need SVC code level 18.104.22.168 or later. Although native attach support is not available for IBM i 6.1 partitions, an IBM i 7.1 partition with native attachment to SVC or Storwize storage systems may have either IBM i 6.1 or IBM i 7.1 partitions as virtual clients in iVirtualization configurations.
Fabric attach configurations are supported. The supported adapters include 8 Gb PCIe Fibre Channel feature numbers 5735 and 5273, as well as 4 Gb Fibre Channel feature numbers 5774 and 5276. The switches that are supported at this time include 8 Gb and 16 Gb IBM SAN b-type switches.
Direct attach configurations are also supported, allowing for an even lower cost entry configuration option. The supported adapters include 4 Gb PCIe Fibre Channel feature numbers 5774 and 5276.
For more information about this announcement, including compatibility and availability information for specific configurations, and best practices for configuration, see the IBM i Technology Updates wiki.
See this techdoc for a summary of IBM i supported storage: IBM i POWER External Storage Support Matrix Summary