“Well, time to open robbed!” Song Lan (a pseudonym) has long been waiting for a long time sitting in front of the computer to see the time is 0:00 to 11 November 2011, could not wait to join in Taobao’s annual large-scale network purchase of promotional activities – “Taobao” Shopping Carnival. Song Lan do not know, in the minutes at 0:00 on the 11th after this, there are 342 million people and with her into Taobao. Of course, she do not know, at this moment, in Taobao’s Hangzhou headquarters of an office,, Taobao technology Ministry of the core system is responsible for people and Senior Fellow, Zhang Wen Song and Taobao group technology expert who, being on the board have to write down the note, see Who is the most accurate guess “the Taobao dual 11″ CDN traffic peak and full-day total amount of transactions.

However, under an atmosphere of seemingly effortless, Zhang Wen Song and his colleagues in their heart how much some apprehension: the net purchase event Taobao various service systems are the first great test, in which the greatest test is yes Zhang Wen Song responsible, just on the line, new structures based on the Intel Atom (ATOM) customization of the processor low-power server CDN system. What would happen because, although there were tested the CDN system can cope with large traffic, but after all the test results, the real, none of the end.

Transaction amount so that after 24 hours, up to 5.2 billion and Taobao Taobao Mall the Taobao laughed, and the heart of Zhang Wen Song finally settled.

Since the energy saving of the required

Internet-related technologies are more familiar with people probably are aware of the CDN. CDN full name Content DeliveryNetwork, content distribution network. Its purpose is to add a new layer of network infrastructure in the existing Internet, the site’s content is released to the closest to the user of the network “edge”, so that users can conveniently obtain the required content, improve the response speed of the user to access the site .

Taobao, Zhang Wen Song said, in order to protect the nearly four hundred million Taobao user shopping experience, the company’s entire network deployment 103 is used to accelerate the CDN node, single-node service capacity greater than 10Gbps, more than 4,000 the number of the CDN the Web the Cache Server .

Of course, support the day-to-day operations of the Taobao far more than several thousand CDN webcache server. The daily power consumption of these servers is very alarming, in the Taobao operating costs accounted for a significant proportion is increasing year by year. Therefore, to save server power consumption, has become have to consider the issue. The most direct way is to meet the performance requirements under the premise, the use than traditional server power-saving low-power servers.

The reason why low-power server power-saving than traditional servers, mainly lies in using a low-power CPU. At the same time a low-power, low-power CPU, also a loss of processing speed. Therefore, consumes less CPU resources used low-power server scenarios. Happens to be CDN WebCache server from the the Taobao entire server system, to meet this requirement, and ultimately, the company decided to try to use a custom low-power servers to replace the traditional server in the CDN node, and at the end of 2009 the official launch of the green low-power server custom items. “Is not just to save a machine”

Custom low-power server, ostensibly save the machine, but in fact is not so simple. “Zhang Wen Song told reporters.

Traditional low-power processors on the market, its power-saving principle, while simplifying the processing logic module out of order on the basis of the original high-performance processor, by controlling the frequency and power consumption of the processor in the leisure to reduce unnecessary consumption. However, the approach is limited by high-performance architecture, the overall reduction in power consumption is not obvious, especially in the IO-intensive business. Taobao is used to accelerate static content CDN WebCache server, the main function is static web pages and images to read and write operations are IO intensive business.

“Therefore, for IO-intensive business, we need to find different from the traditional, lower-power processors and server programs.” Said Zhang Wen Song.

Start at the beginning of the project, select a well-known supplier of chip platform Taobao as a partner, and a prototype was produced in June 2010, but unfortunately, the prototype can not through the online test. Therefore, in August 2010, Taobao more experienced in the whole solution Advanced Micro Devices Inc. and Intel. Ultimately, the efforts of the tripartite customized based on the Atom processor D525 low-power server is successful, the implementation of large-scale deployment began in June 2011 in Taobao.

In Hangzhou, China number of the engine room, responsible for the customization of the server product manager He Yanfeng led reporters toured the one built by the low-power server CDN node cluster. Among them, a 2U space to put Taiwan Ling dynamic low-power servers (8 servers to share a chassis) and single server power consumption of only 25W, that is, the overall power consumption of the eight low-power server only 200 watts. 200 watts is what concept? He Yanfeng, pointing to a server in the CDN node cluster, and told us that that is a common server on the market, is mainly responsible for the scheduling function, the power consumption of 150W, accounting for the 1U space. Two relatively high-density low-power, low-power server advantages are clear.

It is worth mentioning that Zhang Wen Song and his colleagues found that Taobao CDN cache object has the feature is: 80% of 18KB below the object number of the total number of, but storage capacity is only less than 40%; at the same time, 80% was access to the object storage space occupied by less than 20%. Means “hot data” (access to the high frequency content) accounts for the space is actually very small, and “cold data” (access to low-frequency content) required to store a large amount. Therefore, Taobao specifically for the low-power server to the introduction of tiered storage mechanism, a single low-power server’s hard disk by a 80GB SSD disk and two 500GB SATA drives. In this way, the “hot data” stored in the SSD drive, the “cold data” stored in the SATA disk, thereby taking into account the speed, capacity and cost. Tiered storage scheduling software from the Taobao independent development.

In February 2011, the Atom low-power server into volume production. Then, Taobao is busy start to the system optimization. Zhang Wen Song told reporters, without optimization, the single low-power server QPS (queries per second rate) is about 900 or so, almost from their stated goal (1000QPS). However, when they will be hard to access mode to ACHI / RAID, the QPS immediately jumped to 1300; and then by optimizing the work of the IO, network, and the SMP the affinity, the QPS number reaches 1700, far exceeding the original expectations.

“We are rewriting a lightweight Cache software, the OPS number can be raised to 1900.” Said Zhang Wen Song.

It is reported that Taobao total deployment of more than a dozen low-power CDN node cluster deployed a total of about 800 Atom low-power servers. Most of the Atom node services to the 10Gbps uplinks limit -, at this time of a single low-power server services QPS 1200, the CPU load does not exceed 70%, overall I / O However, about 50%, and overall cache service response time below 20 milliseconds.

“The Amoy Po ‘Double 11′ shopping carnival, our CDN to withstand more than 90% of the entire network traffic, this day of CDN bandwidth, peak to reach more than 800 Gbps can be said to truly passed the test.” Said Zhang Wen Song. After Taobao “double 12″, brought a greater flow “peak”, the Taobao CDN is also safely withstand.

He Yanfeng also revealed that they also got the Intel SandyBridge (15W) low-power processors (Intel’s flagship processor in the micro-server one) samples and the performance test, and the CDN cache applications.

“SandyBrige low power consumption (15W) processors using dual-core architecture, clocked at only 1.2GHz, have 3MB L3 cache. If you look at the frequency of words, it is difficult to imagine that such a processor, how superior performance, test results but unexpectedly, the performance of a single server to 4500QPS almost this low-power server 3 times, while consuming less than 2W. “He Yanfeng said.

Therefore, as long as the paragraph appropriate processor price, Taobao SandyBrige (15W) in the next-generation low-power server processor.

Environmentally conscious and practicing the open source

“We customize the server is not the same as with traditional custom, the traditional custom is a buyout in the form, for example, I told you (manufacturers) customized server, you can not be sold to a third party and we Taobao is an open source mentality We feel that despite this low-power server CDN demand for Taobao customized, but the low-power server environment protection and energy, while the CDN system is the foundation of the entire Internet service, Taobao will it open source to go out and to encourage manufacturers to this products sold to someone else, on the one hand, promote the development of “green” the entire Internet server industry, on the other hand, highlight the development strategy of Taobao. “He Yanfeng told reporters.

It should be noted that the Taobao low-power server custom projects in the industry is fairly advanced, and its value is self-evident. On the other hand, although at home and abroad, many research institutions, companies are developing low-power servers, low-power server project (design, specifications and application data) such as Taobao selfless open source, using the words of Zhang Wen Song: “The world is also the first”.

And Taobao does not simply its low-power server custom project open source, but as a starting point, and Intel, AMD and other vendors, jointly launched the “Open Source Green Computing Project (http://www. greencompute.org /). Zhang Wen Song stressed that the project’s goal is to promote the Internet as a whole hardware infrastructure (servers, network devices, IDC room, rack and power), energy saving and environmental protection.

In the open-source Green Computing website, there are only Atom low-power server, a custom of the “green” products, Zhang Wen Song earnestly hope that the more peers to join in, and jointly promote the development of the industry of “green computing”.

Interview Notes] two emotion

Taobao, people not only personal experience of domestic Internet users, IT technical strength strong trigger reporter hearts of the two emotion:

First, Taobao, Tencent and other domestic Internet users have about gradually with IT vendors, the strength of the IT industry. For example, Zhang Wen Song said, Intel no MicroServer (micro-server) strategy, the Atom processor was originally not for servers, it is Taobao green low-power server custom project is a direct impact on the advanced Intel MicroServer strategy. Currently, there are news, Intel plans to launch new Atom processor for network-attached storage and entry-level server product line in the second quarter of 2012.

Second, the bright future of low-power servers. Taobao’s practice has proved that do not require too much CPU of the I / O type applications, such as CDN caching services, site storage and backup services, enterprise logging system using low-power server can harvest better performance / power ratio and cost-effective. Therefore, low-power server is bound to exist as a new branch in the server category.

At the same time, a focus on low-power server war is also ready. Intel the MicroServer strategy, and AMD also have plans, mobile chip, the field of “big brother” ARM is a step by step, trying to cut into the server market by low-power server is well-known fact. The war which side wins, the industry have different views. However, I think the ARM chip software weak ecological environment has always been insurmountable obstacles in the short term. For example, in green and low-power server Taobao custom project, Taobao was initially considered the ARM chip, but to take into consideration the cost of software migration finally dropped. Intel With strong R & D and marketing capabilities, as well as upstream and downstream vendors, users between good and deep relationship, will be able to occupy a favorable position.