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IBM Storage

Hu Yoshidas blog

Enterprise Storage Systems in a Midrange package
Tue, 04 Dec 2018

High end enterprise storage systems are designed to scale to large capacities, with a large number of host connections while maintaining high performance and availability. That takes an architecture where a host can access any storage port and have direct access to a number of storage controllers which can service I/O requests and process their data services requirements. This takes a great deal of sophisticated technology and only a few vendors can provide such a high end storage system. Hitachi’s, high end, Hybrid Virtual Storage Platform (VSP) G1500 and All Flash VSP F1500 arrays provide this capability which is made possible through a switch architecture which dynamically connects front end ports with controllers and a global cache with backend device controllers.

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For the midrange user where cost is a key factor and massive scalability is not required, the architecture has to be changed to trade off scalability for reduced cost. However, that trade off often means that some advanced enterprise functions like distance replication and zero data loss recovery would be compromised. With recent advances in Intel multicore technology and PCIe extensions, it is now possible to scale down these systems to reduce costs while still providing these advanced enterprise functions. The recent models of the Hitachi Vantara VSP Hybrid G and All Flash F series storage arrays, now provide, cost efficient, scaled down versions of the G1500 and F1500 Enterprise storage arrays, without any loss in enterprise functionality. This was done by consolidating the VSP controller, cache memory, and interconnects onto a cost optimized, two controller architecture which utilizes Intel’s latest multicore processors with high speed PCIe interconnects. These two controllers are configured as Active/Active controllers, which means that any I/O can access any device through either controller.


Midrange storage arrays are configured with dual controllers for availability. However, there is a great deal of difference in how the two controllers are configured. Most are configured as Active/Passive or Asymmetric Logic Unit Access Asymmetric (ALUA). Very few are Active/Active. The configuration of the storage controllers is a key differentiator when it comes to the performance and functionality of the storage system. Here are the differences between the different types of controller configurations.

Active Passive.png




Active Active.png


The VSP’s Active/Active configuration is made possible through the concatenation of the cache that is attached to each controller. Both controllers work with the same cache image of the storage LUN. This configuration is also known as Active/Active Symmetric since both controllers can process the I/O request versus the prior asymmetric configuration above. This requires additional routing information that is provided by the Storage Virtualization Operating System that is available in all models of the VSP series. This Active/Active capability provides many benefits. We don’t need to worry about LUN ownership as in the case of asymmetric controllers. This provides the ability to use VMotion for live migration of running virtual machines between servers that don’t have identical primary failover controller assignments, with zero downtime, continuous service availability, and complete transaction integrity. This also provides the ability to load balance across a SAN without the worry of creating a performance issue on the storage. Since the VSP can virtualize external storage, this also makes it possible to process a cache image of a LUN from an externally attached storage system. This ability to virtualize external storage enables the extension of the useful life of legacy storage systems and the non-disruptive migration of data to and from an external systems as I posted in a previous blog.


The latest versions of our midrange offerings, the Hybrid VSP G350/G370 and All Flash VSP F350/F370 come in a cost effective 2U of rack space with the enterprise features of our high end and over 1 million IOPS for the VSP F370. All priced and packaged for the midrange.


On the higher end, which many refer to as the entry enterprise, we offer the Hybrid VSP G700/G900 and All Flash VSP F700/F900 that can scale to 2.4 million IOPS and comes in 4U of rack space. The differences in the model numbers is based on the number of Intel processors and cores. Both Hybrid and All Flash entry enterprise models have the same dual controller Active/Active design as the midrange models but with many more Intel cores, memory, front end ports, back end ports, and higher internal bandwidths. Here are the specifications for the Entry Enterprise Models.


VSP Data Sheet.png

The Hybrid VSP G1500 and All Flash VSP F1500 are included to show the full scale out capability of their switch architecture. The VSP G/F1500 is a multi-controller architecture in which the processors, memory modules, front end ports and back end ports are all connected through an internal non-blocking, cross bar, switch, which enables a LUN to be accessed directly through any port without the overhead of passing control between controllers.

Cross bar switch.png


There are other architectures which support more than two controllers, but those types of architectures involve a great deal of overhead and complexity. No matter how many controllers you hook together, I/O requests for a LUN have to be processed through one controller. So If your I/O request comes in from another controller port, the I/O has to be passed to the controller that owns the LUN. This overhead and complexity in managing these extra transfers and responses, creates more overhead than if you had a single controller.

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In the case of the VSP G/F1500 the switch architecture would allow the controllers, cache, and LUNs to be assigned dynamically. Having two controllers adds redundancy but if the two controllers are not configured as Active/Active controllers, you will not get the load balancing advantages of having the additional controller. Adding more controllers to a two controller architecture, just adds more overhead and more rack space without any benefits in cost and performance.


The VSP family of storage arrays, provides a choice of cost optimized configurations from midrange to high end scalable enterprise systems, all running the same software and providing the same functionality to help our customers preserve their investments in policies and procedures and leverage their ecosystem-related investments. Although there is a difference in architectures we are able to simulate the architectural differences in software so that all the models have the same functionality even when it is scaled down to the midrange price and packaging. Our dual controller architectures are fully Active/Active which differentiates us from many other midrange and entry enterprise systems.

Extending Democratization of Storage Services Through Virtualization
Wed, 14 Nov 2018

In my last blog post I explained how Hitachi Vantara’s All Flash F series and Hybrid G series Virtual Storage Platform (VSP) Systems can democratize storage services across midrange, high end, and mainframe storage configurations. Midrange customers can enjoy all the high end functions that are normally only available on high end systems since Hitachi’s VSP platform is powered by one Storage Virtualization Operating System RF (SVOS RF).

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In that post I shared the CRN interview with Dell’s Vice Chairman Jeff Clarke, where he announced their plan to consolidate four disparate midrange products and focus on one. That plan immediately drew questions from other vendors as to how they would manage the migration when they transition from the old to the new. This plan was also limited to midrange products and did not extend to high end where features like active/active metro clustering (VPLEX) and SRDF replication are only available on their VMAX and PowerMax systems. SRDF replication is used to provide non disruptive migration for VMAX systems, but is not available on their midrange products.

In other words, their storage plans do not go far enough and do not address the key question of migration for their midrange storage. Hitachi Vantara can provide a solution for EMC Dell users by virtualizing their current EMC Dell storage arrays and democratize the use of Hitachi VSP high end enterprise storage services, making them available to all EMC DELL users, whether they are midrange, high end or mainframe. This capability is not limited to EMC Dell but is applicable to any vendor’s fibre channel or iSCSI attached storage arrays. As the name implies, the signature feature of our VSP is virtualization. Our approach to storage virtualization is unique in the industry since we do the virtualization in our Virtual Storage Platform (VSP) controllers with a Storage Virtualization Operating System RF (SVOS RF). Hitachi storage virtualization can greatly simplify storage management, particularly when used to consolidate and virtualize arrays from multiple storage vendors or multiple storage array architectures from the same vendor. We announced storage virtualization in 2004 with our Universal Storage Platform (USP). Hitachi was one of the first to announce storage virtualization and has carried that forward in our latest VSP Hybrid (G Series) and All Flash (F Series) storage systems.

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While other vendors approached storage virtualization through the use of appliances sitting on the Storage Area Network (SAN), Hitachi’s unique storage architecture enables the virtualization to be done in the storage controller. The advantage of this approach ensures that Hitachi storage virtualization would have the same reliability, availability, scalability, and performance of an enterprise class storage system, rather than the limited capabilities of an appliance sitting on the SAN. Externally attached, fibre channel or iSCSI, heterogeneous storage is presented as a common pool of storage to the VSP controller and benefits from all the Hitachi enterprise features of the VSP such as Active/Active Metro Clustering, three data center disaster recovery, predictive analytics, and automated management of common workflows. Other vendors’ midrange and enterprise storage, which lack these features, are immediately upgraded with these services when they attached to the VSP. Our approach to storage virtualization is a perfect complement for server virtualization and we were the first storage virtualization vendor to certify with VMware.


Virtualized third party storage can also benefit from VSP’s Storage Plug-in for Containers. Containers are a new form of lightweight and portable operating system virtualization without the overhead of an operating system image. All the necessary executables are inside a container; binary code, libraries, and configuration files to run microservices and larger applications. Containers were designed to be stateless which means that its disk files go away when the container goes away. In order to persist the data and make it easier to manage storage, Docker introduced a set of commands for volume management. This enables storage vendors to create plugins to expose their storage functionality into the Docker ecosystem. Hitachi Storage Plug-in for Containers lets you create containers and run stateful applications by using Hitachi VSP series volumes, including externally virtualized volumes, as dynamically provisioned persistent volumes. Hitachi Storage Plug-in for Containers utilizes built-in high- availability to enable a Docker swarm manager or a Kubernetes master node to orchestrate storage tasks between hosts in a cluster. Storage Plug-in for Containers can also be used in non-clustered environments.


Since external storage uses the licensed services of the host VSP, there is no need to have separate licenses for the external storage. This not only reduces license fees, but also reduces the operational cost of managing features and licenses on the attached storage systems. Virtualization can further reduce costs by extending the life of legacy systems that have already been capitalized or reduce costs by non-disruptively migrating systems when a refresh is required.


According to legacy systems are the Achilles heel for digital transformation. “Unfortunately, many businesses today are hard-coded in technology investments of the past: legacy systems – containing the data that they need to make decisions today and drive insights. Now more than ever, reliance on legacy systems is one of the biggest hurdles in the digital transformation journey.”


When it comes to upgrading legacy infrastructure, the biggest challenge is the upgrade of storage systems. Unlike compute and network infrastructure, storage is stateful, because it has data that must be moved from the old to the new storage system. This movement of data takes time and as the amount of data continues to increase, the data migration extends into days, weeks, and even months. The least disruptive and easiest way to move data is through storage virtualization. Virtualization of legacy storage ensures that applications can continue to access the data while it is being moved in the background. The VSP's bidirectional FC and sSCSI ports allow simultaneous host and external storage connectivity without the need for dedicated "eports" and host ports. Logical device migrations are able to proceed while the original logical device remains online to the hosts and the VSP will seamlessly switch over the mapping from the source logical device to the target logical device when completed. No changes to host mapping are required.


Appliance based virtualization systems, can move data in the back ground, but performance, reliability, and scalability are limited by the capabilities and resources of the appliance compared to a fully functional enterprise virtualization engine with its large cache and large number of bi-directional ports. Utilizing an enterprise storage controller also leverages the built-in security features of the controller and management interfaces such as antivirus, role based access for secure management, authentication and authorization, audit logging, and directory services.


So, if your storage vendor is planning to consolidate their storage platforms without a plan for migration, or you are struggling with a number of legacy storage platforms and would like to upgrade to the latest enterprise capabilities without ripping and replacing your storage estate, please consider using Hitachi’s VSP storage platform to help you with the migration and consolidation. Our VSP systems can come without any internal storage attached in the event that you already have enough capacity in your legacy storage and you want to virtualize and extend the useful life of your current storage, or you want to use it as a sling box to move data across storage systems. However, the biggest benefit would be to leverage all the capabilities that are available in the VSP/SVOS RF