3. Data Center Overview
3.6. Active Components / Network Hardware
3.6.2. IT Infrastructure Basics (Server and Storage Systems)
Active components, if they are network-compatible, have LAN interfaces of various types. These are specified by the technology used for the transmission (transmission protocol, e.g. Ethernet), speed (100 Mbit/s, 1/10 Gbit/s), media support (MM/SM, copper/fiber) and interface for the physical connection (RJ45, LC, etc.).
There are two types of latencies (delay) in the transmission of data for network-compatible devices: • Transfer delay (in µs/ns, based upon medium and distance)
• Switching delay (in ms/µs, based upon device function, switching/routing)
One must therefore pay special attention to the latency of active components to ensure that the delay in the data communication is as low as possible. This does not imply, however, that cabling quality does not have an effect on data transmission.
On the contrary: Other factors like crosstalk, attenuation, RL, etc. play an important role in a clean signal transmission.In addition, distances between signals are becoming smaller as a result of continually growing transmission rates and other factors, while signal levels are becoming smaller as a result of enhanced modulation types. Therefore, transmissions are becoming more susceptible to interference, i.e. transmissions are becoming more sensitive to outside influences. In addition, performance reserves which can stand up to future data rates are in demand more and more for cabling components.
In the final analysis, the typical investment period for cabling extends to over 10 years, as compared to 2 to 3 years for active components. Wanting to save costs in data center cabling would therefore certainly be the wrong investment approach, especially since the percentage of this investment to total investments for a data center is very small (5 % to 7 %) In addition, having to replace cabling is tied to enormous expenditure and, in the case of switches for example, leads to a minor interruption in the data center if redundancy does not exist.
Decision makers must be aware here that the cabling structure in the data center, along with all of its components, represents the basis of all forms of communication (e-mail, VOIP, etc.)–for a long period of time!
Server (Single Server)
This term denotes either a software component (program), in the context of the client/server model, or a hardware component (computer) on which this software (program) runs, in the context of this concept. The term “host” is also used in technical terminology for the server hardware component. So whether a server is meant to denote a host or a software component can only be known from context, or from background information.
Server as software:
A server is a program which provides a service. In the context of the client/server model, another program, the client, can use this service. Clients and servers can run as programs on different computers or on the same computer.
In general, the concept can be extended to mean a group of servers which provide a group of services. Examples are mail servers, (extended) web servers, application servers and database servers. (also see section 1.2)
Server as hardware:
The term server for hardware is used…
• …as a term for a computer on which a server program or a group of server programs run and provide basic services, as already described above.
• …as a term for a computer whose hardware is adapted specifically to server applications, partly through specific performance features (e.g. higher I/O throughput, higher RAM, numerous CPUs, high reliability, but minimal graphics performance).
Server Farm
A server farm is a group of networked server hosts that are all of the same kind and connected to one logical system. It optimizes internal processes by distributing the load over the individual servers, and speeds up computer processes by taking advantage of the computing power of multiple servers. A server farm uses appro- priate software for the load distribution.
Virtual Server
If the performance provided by a single host is not enough to manage the tasks of a server, several hosts can be interconnected into one group, also called a computer cluster. This is done by installing a software component on all hosts, which causes this cluster to appear as a single server to its clients. Which host is actually executing which part of a user’s task remains hidden to that user, who is connected to the server through his/her client. This server is thus a distributed system.
The reverse situation also exists, in which multiple software servers are installed onto one high-performance host. In this case, it remains hidden to users that the different services are in reality being handled by only a single host.
Examples of well-known providers of virtualization solutions include VMware, Citrix and Microsoft.
Rack Server
Rack servers combine high performance in a small amount of space. They can be employed in a very flexible manner, and are therefore the first choice for constructing IT infrastructures that are scalable and universal. In June of 2010, Tec-Channel created a list of the most popular rack servers from its extensive, detailed database of products:
• HP ProLiant DL380 • IBM System x3950 • Dell PowerEdge R710 • HP ProLiant DL370 G6 • HP ProLiant DL785 • Dell PowerEdge 2970 • Dell PowerEdge R905 • Dell PowerEdge R805 • Dell PowerEdge R610
As an illustration, the key performance features of the first three models are listed below:
HP ProLiant DL380 IBM System x3950 Dell PowerEdge R710
Construction 2U rack 4U rack 2U rack
Main memory (max.) 144 GByte 64 GByte 144 GByte
Processor Intel Xeon 5500 series;
Intel Xeon 5600 series Intel Xeon 7400
Intel Xeon 5600 series; Intel Xeon 5500 series
Storage (max.) 16 TByte 2.35 TByte 6 TByte
Network ports 4 x Gbit Ethernet 2 x Gbit Ethernet 2 x 10 Gbit Ethernet
Power supply 2 x 750 watt power
supplies 2 x 1,440 watt power supplies 2 x 570 watt power supplies Pizza Box
The term pizza box, when used in a server context, is generally a slang term for server housing types with 19-inch technology and a single height unit.
Blade Server
Blade systems (blade, blade server, blade center) are one of the most modern server designs and are the fastest growing segment of the server market.
However, they do not differ from traditional rack servers in terms of operation and the execution of applications. This makes it relatively easy to use blades for software systems that already exist. The most important selection criteria for blade servers are the type of application expected to run on the server and the expected workload. In consideration of their maintainability, provisioning and monitoring, blades on the whole deliver more today than their 19-inch predecessors, yet are economical when it comes to energy and cooling. For example, a Blade Center,an IBM term, provides the infrastructure required by the blades connected inside it.In addition to the power supply, this includes optical drives, network switches, Fibre Channel switches (for the storage connection) as well as other components.
The advantage of blades lies in their compact design, high power density, scalability and flexibility, a cabling system that is more straightforward with significantly lower cable expenditure, and quick and easy maintenance. In addition, only a single keyboard-video-mouse controller (KVM) is required for the rack system.
A flexible system management solution always pays off, especially in the area of server virtualization. Since in this situation multiple virtual servers are usually being executed on one computer, a server also requires multiple connections to the network. Otherwise, one must resort to costly processes for address conversion, similar to what NAT (Network Address Translation) does. In addition, the level of security is increased by separating networks. Many manufacturers allow up to 24 network connections to be provided for one physical server for this purpose, without administrators having to change the existing network infrastructure. This simplifies integration of the blade system into the existing infrastructure.
TecChannel created the following list of the most popular blade servers from its extensive, detailed product database:
• 1st place: IBM BladeCenter S
• 2nd place: Dell PowerEdge M610
• 3rd place: Fujitsu Primergy BX900
• 4th place: Fujitsu Primergy BX600 S3
• 5th place: Fujitsu Primergy BX400
• 6th place: IBM BladeCenter H
• 7th place: Dell PowerEdge M910
• 8th place: Dell PowerEdge M710
• 9th place: HP ProLiant BL460c
• 10th place: Dell PowerEdge M710HD
This list of manufacturers must also be extended by Oracle (Sun Microsystems), Transtec, Cisco with its UCS systems (Unified Computing System) and other popular manufacturers.
The key performance features of the first three models are listed below:
IBM BladeCenter S Dell PowerEdge M610 Fujitsu Primergy BX900
Construction 7U rack 10U rack 10U rack
Server blade module BladeCenter HS22 PowerEdge M610 Primergy BX920 S1
Front mounting slots 6 x 2 CPU plug-in unit and others
16 x half height or 8 x full height
18 x half height or 9 x full height
Processor Intel Xeon 5500 Intel Xeon 5500 and 5600
series Intel Xeon E5500 series
Network ports 2 x Gbit-Ethernet and TCP/IPOffloadEngineTOE
2 x Gbit Ethernet (CMC); 1
x ARI (iKVM) 4 x Gbit Ethernet
Power supply 4 x 950 / 1,450 watts 3 x non-redundant or
6 x redundant, 2,360 watts 6 x 1,165 watts
Mainframes
The mainframe computer platform (also known as large computer or host) that was once given up for dead has been experiencing a second life. At this point, IBM, with its System-z machines (see image to left), is practically the only supplier of these monoliths.
The mainframe falls under the category of servers as well.
System i (formerly called AS/400 or eServer, iSeries or System i5) is a computer series from IBM.
IBM’s System i has a proprietary operating system called i5/OS and its own database called DB2, upon which a vast number of installations run commercial applications for managing typical company business processes, as a server or client/server application. These can typically be found in medium-sized companies.
TheSystemialsofallsundertheservercategory.Someofthesesystems can be installed in racks.
Storage Systems
Storage systems are systems for online data processing as well as for data storage, archiving and backup. Depending upon the requirements for their application and for access time, storage systems can either operate as primary components, such as mass storage systems in the form of hard disk storage or disk arrays, or as secondary storage systems such as jukeboxes and tape backup systems.
There are various transmission technologies available for storage networks:
• DAS – Direct Attached Storage
• NAS – Network Attached Storage
• SAN – Storage Area Networks
• FC – Fibre Channel (details in section 3.8.3)
• FCoE – Fibre Channel over Ethernet (details in section 3.8.4)
Someofthesestoragearchitectureshavealreadybeenmentionedinsection1.2thatdescribesthebasicelements of a data center.
Storage Networks
NAS andSANare the best-known approaches for storing data in company networks.New SAN technologies like Fibre Channelover Ethernethave been gaining in popularity, because with FCoE the I/O consolidation from merging with Ethernet LAN is attractive for infrastructure reasons (see section 3.7.2.). Nevertheless, all storage solutions have disadvantages as well as advantages, and these need to be considered in order to implement future-proof storage solutions.
DAS – Direct Attached Storage
DirectAttachedStorage(DAS) or ServerAttachedStorage is a term for hard disks in a separate housing and that are connected to a single host.
The usual interfaces for this implementation are SCSI (Small Computer System Interface) and SAS (Serial Attached SCSI). The parallel SCSI interface with its final standard Ultra-320 SCSI was the forerunner to SAS. However, it represented the physical boundaries of SCSI, since the signal propagation delay of individual bits on the parallel bus were too different. The clock rate on the bus had to be limited so that the slowest and fastest bit could still be evaluated at the bit sample time. However, this process conflicted with the goal of continuously increasing bus performance. As a result, a new interface was designed, one that was serial and therefore offered greater performance reserves. Since the Serial ATA (S-ATA) serial interface had already been introduced into desktop PCs a few years earlier, it also made sense to keep SCSI’s successor compatible with S-ATA to a great extent, in order to reduce development and manufacturing costs through its reusability.
Nevertheless, all block-oriented transmission protocols can be used for direct (point to point) connections.
NAS – Network Attached Storage
Network Attached Storage (NAS) describes an easy to manage file server. NAS is generally used to provide independent storage capacity in a computer network without great effort. NAS uses the existing Ethernet network with a TCP/IP protocol like NFS (Network File System) or CIFS (Common Internet File System), so computers that are connected to the network can access the data media. They often operate purely as file servers.
An NAS generally provides many more functions than just assigning computer storage over the network. In contrast to Direct Attached Storage, an NAS is therefore always either an independent computer (host) or a virtual computer (Virtual Storage Appliance, VSA for short) with its own operating system, and is integrated into the network as such. Many systems therefore also possess RAID functions to prevent data loss arising from defects.
NAS systems can manage large volumes of data for company uses. Extensive volumes of data are also made quickly accessible to users through the use of high-performance hard disks and caches. Professional NAS solutions are well-suited for consolidating file services in companies. NAS solutions are high-performance, redundant and therefore fail-safe, and represent an alternative to traditional Windows/Linux/Unix file servers.
Due to the hardware they use and their ease of administration, NAS solutions are significantly cheaper to imple- ment than comparable SAN solutions. However, this is at the expense of performance.
SAN – Storage Area Networks A Storage Area Network (SAN) in a data processing context denotes a network used to connect hard disk subsystems and tape libraries to server systems.
SANs are designed for serial, conti- nuous, high-speed transfers of large volumes of data (up to 16 Gbit/s). They are currently based on the imple- mentation of Fibre Channel standards for high-availability, high-performance installations. Servers are connected into the FC-SAN using Host Bus Adapters (HBA).
The adjacent graphic shows a typical network configuration in which the SAN network is being run as a separate network by means of Fibre Channel. With the continued development of FCoE (Fibre Channel over Ethernet), this network will merge with Ethernet- based LAN in the future.
FC and the migration to FCoE is shown in sections 3.7.2 and 3.8.3 as well as 3.8.4.
Server
LAN aggregation
& core switch
FC SAN
switch
LAN
access
switch
Ethernet
Ethernet
FC Storage
FC
FC
FO
Copper
Storage Solutions
The demand for storage capacities has been steadily growing as a result of increasing volumes of data as well as require-ments for data backup and archiving. Cost efficiency in the area of company storage is therefore still a central theme for IT managers. Their goal is to achieve high storage efficiency by using their existing means and hardware in combination with storage virtualization, Cloud Storage (Storage as a Service) and consolidation.
The popularity of the Unified Storage approach, a system that supports all storage protocols, has been picking up speed in new storage acquisitions.
Racks that contain only hard disks are finding their way into more and more data centers and are being supplied preassembled by solution providers such as:
• NetApp • EMC • HDS Hitachi Data Systems
• HP • IBM • Oracle (Sun Microsystems)
Secondary storage solutions like jukeboxes and tape backup systems no longer play a part in current storage solutions.However, IT managers must not ignore the conventional backup as well as data storage that is legally required – key word compliance – for all the storage technologies they use.