Fujistu ETERNUS DX Hardware Features & Architecture
Based on a unique and consistent system design, ETERNUS DX is a seamless family of disk storage systems ranging from entry to enterprise class. The main design principles of ETERNUS DX are scalability and flexibility. In order to provide an economic storage solution that satisfies the needs of smaller businesses which have tight budgets, the ETERNUS DX60 S2 supports all the basic functionalities. In the highly demanding enterprise segment, the ETERNUS DX8700 S2 has been enhanced to provide peak loads of up to 1 million IOPS. Its superior performance has been proven in various customer deployments and SPC benchmarks.
The scalable entry and mid-range segments have ETERNUS DX S3 models which are based on enhanced performance architecture. They provide unified block and files access. All models within the same generation use the same types of disks, disk shelves, racks, cables and other components. Only the controller module is unique to each model. The aim is to minimize the amount of work and costs involved in operations, training and migration. Furthermore, this family concept enables easy upgrading – from a smaller model to a bigger one – as you just have to change the controller module. All the other components can still be used.
Scalable Entry Models
The scalable entry models – ETERNUS DX100 S3 and ETERNUS DX200 S3 – are designed in a compact style to ensure an optimized footprint. They comprise the following hardware:
Controller Enclosure (CE): The CE contains the Controller Modules (CM) and Power Supply Units (PSU) in the rear as well as the disk drives installed in the front. The controller enclosure can be equipped with either one controller module (single controller model) or with two modules (dual controller model). A single controller model can be easily upgraded to a dual controller model by just installing an extra controller.
Drive Enclosures (DE): They contain disk drives installed in the front as well as power supplies and expanders in the rear. The SAS expander is a unit that controls the connection to the controller modules. The disk enclosures can be equipped with one or two expanders depending on the number of controller modules. The various types of disk drives are described in detail in the following sections.
The Controller Module (CM) runs the firmware-based operating system and contains host interface ports, drive interface ports, cache memory, a System Capacitor Unit (SCU), RAID control processors, RAID controller firmware, and Ethernet ports. Channel Adapters (CA), providing the connection to the host, are installed in each controller module and drive-side interfaces are installed on-board. The 2 CMs are interconnected via PCI Express. SAS interfaces between the CMs are cross-connected to provide a redundant path to the disks installed on CEs. A Drive Enclosure (DE) also has two independent interface ports that are directly connected to two CMs for path redundancy.
The mid-range models of the ETERNUS DX S3 (ETERNUS DX500 S3 and ETERNUS DX600 S3) are designed to provide the highest possible capacity, performance and reliability levels. They contain the following hardware:
Controller Enclosure (CE): The CE contains the Controller Modules (CM), Channel Adapters (CA), PCI Express Flash Module (PFM), Battery Backup Unit (BBU) and Power Supply Units (PSU). Unlike the entry-level models, the controller enclosure does not contain disk drives.
Drive Enclosures (DE): The minimum configuration consists of one DE in addition to the CE. Expansion drive enclosures can be added according to the capacity required. The same drive enclosures can be used in any ETERNUS DX S3 model, ensuring a smooth upgrade and full investment protection. Disk enclosures supporting 2.5” and 3.5” disk drives are available.
The basic architecture of the system consists of two interconnected CMs (via PCI Express), each having two Channel Adapters (CA), and two drive-side interfaces installed. It also supports high-speed PCI Express Flash Modules (PFM) as large capacity cache – the Extreme Cache (EXC) – which provide higher performance with less number of disk drives, optimizing costs and power consumption. The EXC supports hot-swapping. The system can host up to four modules providing up to 5.6 TB cache capacity for read operations. Unlike many implementations, the PFM modules are mounted in the controllers – not in the drive enclosures – providing some benefits, such as:
■ Short latency due to direct PCI Express connection to CPU
■ Better utilization of the drive enclosures, as no DE slots need to be dedicated for EXC
■ I/O performance of the drive enclosures are not impacted
The schematic architecture of the ETERNUS DX8700 S2 high-end model of the ETERNUS DX family is shown below as it differs slightly from other models. While most of the basic functional blocks are the same, the connection between the controller module and the disk drives located in the drive enclosures is realized using the back-end routers (BRT), which are not part of the controller, but rather separate modules installed according to the number of disk enclosures.
In order to ensure reliable operation and high availability, the ETERNUS disk storage systems have a fully redundant configuration and hot maintenance capability. The interconnection of the CMs is duplicated. A drive enclosure (DE) has also two independent interface ports that are directly connected to two CMs for path redundancy.
The use of redundant components and multiple controller-to-drive connections ensures exceptional reliability. Hardware components supporting hot-exchange and hot-expansion features not only enable firmware upgrades during system operation, but also provide capacity expansion together with the LUN expansion feature where DEs or HDDs are added as needed.
Symmetric Multi-Processing and 64-bit Operating System
ETERNUS DX S3 systems use powerful Intel® multi-core processors to provide leading performance. Symmetric multi-processing is a technology that allows controlling multiple processor cores by one operating system. Combined with using the latest 64-bit operating system, it offers many benefits, such as:
■ Memory resources are better utilized
■ Performance is dramatically increased as the core sufficiency ratio is improved by sorting required transactions flexibly even when cores are increased
■ Better resource optimization as resources are not bound to cores
■ Higher flexibility and processing performance as 64-bit operating system CPU can handle high-volume data
The figure below shows the benefit of symmetric multi-processing, as many different tasks can be executed in parallel, resulting in significant performance increase.
The ETERNUS DX S3 provides different types of host interfaces, offering customers full flexibility in selecting the most appropriate data center infrastructure. Fibre channel is the most widely used storage networking technology as it is highly reliable, efficient and secure. Up to 16Gbit/s bandwidth is supported, offering the highest possible bandwidth.
1Gbit/s & 10Gbit/s iSCSI are also supported for connecting to IP networks. They are simple to operate and hence preferred by many customers. 10Gbit/s FCoE (Fibre Channel over Ethernet) is a new networking technology that encapsulates FC frames over Ethernet networks, which allow using the FC protocol over existing Ethernet networks combining the benefits of both technologies. The backend interfaces are realized by 12Gbit/s SAS.
Types of disk drives
As the storage requirements differ according to the type of data and the frequency of its usage, various types of disk drives need to be supported in order to allocate the right disks for each type of data. Some data is mission-critical; it has to be accessed immediately in order to avoid revenue loss or productivity degradation. This data must be stored on drives with very high performance, such as SSD (Solid State Drives). On the other hand, some types of data do not require very high performance, but need to be stored for longer periods; it can thus be stored on more cost-efficient, high-capacity disks, such as Nearline SAS disk drives, enabling the customer to balance speed, capacity and costs.
In addition, 2.5” and 3.5” enclosures can be mixed in the same storage configuration. SSD, SAS and Nearline SAS disks can be mixed in the same 2.5” drive enclosures. 3.5” enclosures can host Nearline disk drives, which provide up to 4TB capacity.
In addition to manual tiering of data into the appropriate type of disk drives, the ETERNUS DX product family supports Automated Storage Tiering (AST) as described in this site “ETERNUS SF Management Suite”.
Low-power, highly reliable and high-performance Solid State Drives (SSD)
Solid State Drives (SSD) use semiconductor memory to store data. They contain no motors or moving parts, and thus have a much higher read/write access speed and reduced power consumption.
They benefit those applications with high random access requirements, such as databases. In addition, with no motors or moving parts, they are more reliable than disk drives. These features make SSD ideal for Tier 0 storage use. The SSD used in ETERNUS DX have enterprise-class performance and reliability. While maintaining compatibility with traditional disk drives, they support low-power consumption and highspeed operation. If a power failure occurs, SSD in ETERNUS DX can move any data in the volatile memory of the SSD (high-speed DRAM cache) to the flash memory and ensure a safe system halt.
Online SAS disk drives
For data volumes that are frequently accessed, but still do not require the very high performance of SSD, SAS disk drives are used, providing a balanced mix of performance and capacity, while keeping costs at a moderate level.
Cost-efficient, high-capacity Nearline SAS disk drives
Storing infrequently accessed data on high-performance storage devices generates unnecessary costs. To meet the growing demand for cost effective storage of less frequently accessed data, Fujitsu provides high capacity, highly reliable, yet cost-optimized Nearline disk drives in its ETERNUS DX disk storage systems.
This combination of on-line disk drives and Nearline disk drives in the same drive enclosure enables ETERNUS DX disk storage systems to support cost-effective operations, such as disk-to-disk backup and long term storage of reference data.
High-density drive enclosures
High-density drive enclosures are available in order to meet the growing demand for more capacity. They house up to 60 3.5” disk drives in one DE, which can provide up to 240 TB in 4 rack units.
Energy savings – Eco-mode
Power consumption is one of the biggest contributors to the OPEX of any company. It is also a heavy burden on the environment. The disk drives used in all the ETERNUS DX products have Eco-mode support using MAID technology. MAID is an acronym for Massive Array of Idle Disks. This technology extends the life of the disk drives and reduces power consumption bystopping spindle rotation on less frequently accessed disk drives.
Eco-mode reduces power consumption because the disks are powered off during periods of inactivity. This time-controlled mode, based on the scheduled use of specific disks, can be set up for individual RAID groups and backup operations.
Rotations stop when scheduled disks are not accessed for specific periods and then restart when a data access order is received. Full rotation is restored within seconds.
Furthermore, two options are supported to control the power-off of idle disk drives:
■ Scheduled control: disk drives that are inactive for 3 minutes will be powered off
■ Software control: disk drives are synchronously controlled with the accessing server applications