首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
If you have lots of unused storage space on your hard disk, then why not share it with others on the Internet? The benefit could
If you have lots of unused storage space on your hard disk, then why not share it with others on the Internet? The benefit could
admin
2019-08-01
141
问题
If you have lots of unused storage space on your hard disk, then why not share it with others on the Internet? The benefit could be distributed storage for your own files, making them available any time via the web, even if you are nowhere near your computer—indeed, even if your computer is switched off. That idea is what a Zurich-based firm called Caleido is aiming to provide, with a free online storage service known as Wuala that was recently introduced to the public.
【R1】______In particular, its developers, Dominik Grolimund and Luzius Meisser, have used a clever mathematical trick to compensate for the fact that the participating computers will come and go from the internet in an unpredictable way.
【R2】______Copying costs participants both storage space and bandwidth.
Yet there have to be enough copies to ensure that there is at least one available most of the time. If, for example, each computer is online 25% of the time, then a quick calculation shows that you would have to copy each file to 100 different computers to ensure that 999,999 times out of a million there is at least one copy available when a user looks.
【R3】______Instead, Mr. Grolimund and Mr. Meisser plan to break each file into chunks, which can be scattered liberally around the hard disks of participating computers, and then to use a mathematical trick to reconstruct the original file from those chunks.
【R4】______The first step is to convert the file(which is, regardless of what it represents, simply a long string of ones and zeros)into a mathematical function called a polynomial. This is done by splitting it into 100 fragments, which are smaller binary numbers. It is these numbers that are used to define the polynomial. All you have to do is select a suitable number of points from along the polynomial and convert their values into the appropriate mathematical constructs. Scatter these around the host computers and, when someone wants to look at the file, he need recover only 100 of them to have enough data to reconstruct the file from scratch. To have 100 points available 999,999 times out of a million it turns out that you need to scatter a total of 600 of them around. That is an amount of data equivalent to six versions of the original file. Moreover, the system needs the computers linked to it to be available for only 17% of the time, rather than 25% , for this to apply.
【R5】______Most commercial online-storage services use centralized servers. Although these are generally reliable, they do sometimes fail. And when they do, the results are embarrassing.
Though some people may feel sick about scattering their data over hundreds of other computers(even though it will be encrypted), or storing unknown file fragments on their own, Mr Grolimund is sure that Caleido has learnt from other "peer-to-peer" file-sharing systems, and that Wuala is built to handle concerns about the illegal distribution of copyrighted or " inappropriate" content.
[A]This trick, known as Reed-Solomon error correction, is employed routinely to interpret the data on DVDs, but it has not been used before in the volatile world of private computers on the Internet.
[B]One of the characteristics of a polynomial is that a few numbers can nail it down precisely. If a simple polynomial is plotted out on a graph it forms a line.
[C]Online storage is a growing market, especially for backing up data, where reliability is a big concern.
[D]The challenge is how to minimize the number of copies of the same file that have to be distributed.
[E]It has been proved that for online data storage, Wuala is as good to give as it is to receive.
[F]Though the idea underlying it is simple, Wuala requires some nifty technology to make its distributed system work reliably.
[G]But copying every file a hundred times is hugely inefficient.
【R1】
选项
答案
F
解析
作者开篇就提出了网络存储的概念,并随后介绍了Caleido公司推出的被称为wuala的免费在线存储服务。在本段中,作者提到了wuala的开发者多米尼克·格罗里芒德和吕齐西·迈瑟使用了数学技巧来弥补参与电脑在上线下线方面的不可预知性。而[F]“虽然基本思想很简单,但是Wuala的实现还是需要极好的技术来保证其分布系统工作的可靠性”能够很好地承上启下,符合文章的逻辑关系,为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/7m2Z777K
0
考研英语一
相关试题推荐
Writeanessaybasedonthefollowingchart.Inyourwriting,youshould1)interpretthechart,and2)giveyourcommen
Writeanessaybasedonthefollowingchart.Inyourwriting,youshould1)interpretthechart,and2)giveyourcommen
Musicproducesprofoundandlastingchangesinthebrain.Schoolsshouldaddmusicclasses,notcutthem.Nearly20yearsago,a
UnderstandingwhatdistinguishespeoplewhobattlewithAlzheimer’sastheyagefromthosewhosementalacutenessremainsstrong
What’stheenginethatdrivesAmericanbusiness?Innovation?Sweat?Capital?Trycoffee.Fromtheshopfloortotheboardroom,J
Hopemaybethelovely,lyrical,inspiringthingmanypeoplebelieveitis—"thethingwithfeathers,"asEmilyDickinsoncalled
Themajortaskfacingadolescentsistocreateastableidentity.Therearesomedevelopmentaltasksthatenablethemtocreate
Throughouttheyears,musichasbeenacommonthreadthatunitesgenerationsandhadprovidedsocialcommentary,individualexpr
AnonymityisnotsomethingwhichwasinventedwiththeInternet.Anonymityandpseudonymityhasoccurredthroughouthistory.For
AnonymityisnotsomethingwhichwasinventedwiththeInternet.Anonymityandpseudonymityhasoccurredthroughouthistory.For
随机试题
A.潜伏期延长B.活跃期延长C.活跃期停滞D.第二产程停滞E.第二产程延长29岁初产妇,妊娠39周,于晨4时临产,10时自然破膜,20时20分查宫口开大2cm,此时应诊断为
行车中遇到盲人和其他行动不便的行人,应该减速慢行,必要时停车。
素有“契约之民”雅称的是()
对基因转录起负性调节作用的基本要素是
与膝关节屈曲动作相拮抗的最主要肌群是
下列不属于外科运用补法适应证的是
下列哪一项不会引起脑疝
关于试算平衡法,下列说法不正确的是()。
某公司测算,若采用银行业务集中法,增设收账中心,可使公司应收账款平均余额由现在的300万元减至250万元,每年增加相关费用8万元。假设该公司综合资金成本率为20%。要求:计算分散收账收益净额,并判断该公司可否采用银行业务集中法收账。
填入下列横线处的词语,最恰当的是()。以“直面医患关系”为宣传卖点的电视剧《心术》在各个卫视播出后,不但收视率不俗,且引起各界热议,主要是因为该剧所选取的题材令人__________。
最新回复
(
0
)