IBM XIV Storage for the zEnterprise
Even with the latest rev, v3.1, IBM’s open XIV grid storage is not likely to replace DS8800 storage as its recommended zEnterprise storage. Still, with an InfiniBand backplane delivering 4x the performance, the inclusion of 3 TB drives, use of SSD caching (up to 6TB of fast-read SSD) to boost performance and reduce latency, and with 99.999% availability XIV boasts impressive storage chops that might indeed interest a mainframe shop, especially one that was moving toward hybrid computing.
XIV sports an impressive GUI of its own, one that is being ported to other IBM storage products, including the Storwize v7000, SONAS (Scale Out Network Attached Storage), and even the DS8000 lineup. XIV, which takes maximum advantage of built-in automation, had been considered pretty admin-friendly from the start. The latest GUI enhancements, such as the ability to search for any element across all managed systems or a reportedly fast, simple way to apply filters, only makes it easier. Mainframe shops can access the DS8000 GUI through Tivoli.
As z shops move inexorably toward cloud computing, especially private clouds, and hybrid computing XIV storage should increasingly come onto mainframe managements’ radar screen. For starters its extensive autonomic operations takes much of the management labor completely out of the process, meaning it can handle the speed, scale, and complexity of cloud provisioning, especially if a goal is to move to user self-service. In addition, it achieves very attractive price/performance. Finally, XIV scales linearly, with processors added along with the storage capacity, and it achieves 99.999% availability.
The autonomic operation should be particularly attractive. It eliminates sprawl by handling configuration, placement, and provisioning to achieve optimum results. It also eliminates the problem of hot spots due to over-subscription. And it is energy efficient; IBM reports $6445 in annual energy costs (no further details provided). However, in a price/performance benchmark IBM published, XIV beat the Hitachi USP-V. It also beat the DS8800 by a wide margin. Mainframe data center managers, take note.
In terms of throughput as measured in megabits per second (MBPS), however, the DS 8800 was tops at nearly 10,000 MBPS. The Hitachi USP V came next at about 8400 MBPS followed by the XIV Gen 3 at just under 8000 MBPS.
XIV constitutes a true storage grid. It consists of 15 cells, each with CPU, disk, DRAM, and SSD connected via a dual InfiniBand fabric. Each cell also includes a UPS and service modules. In terms of compute power, each XIV rack contains 60 CPU cores and 360 GB DRAM. You can choose 1, 2, or 3TB drives, which allows for a compact footprint. Data is dispersed automatically across all nodes, eliminating the need for RAID groups, and it uses independent parallel caches, which eliminates the need for a global cache. A patented distributed pre-fetch keeps a hot working data set in cache while extreme fault isolation between nodes ensures availability. Finally, performance scales linearly; each module added brings its own CPU, DRAM, SSD, and fast fabric.
Each host, however, sees XIV only a single large elastic block system with 24 8Gbit FC ports and 22 1Gbit iSCSI ports. Performance is boosted with SSD caching. Mainframe shops are not likely to ditch their DS8800 storage for XIV anytime soon. Those shops moving to private clouds and especially Linux on z or Linux on zBX blades, however, may find the XIV ease of operation quite appealing. Also, shops running hybrid workloads can benefit from XIV. Mainframe shops will probably manage XIV through Tivoli.