01-04-2020-Oxford_English_for_Infomation_Technology (1171844), страница 22
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Harddisks are becoming cheaper, but data storagerequirements are higher, so it's better to plan forHSM than assume disks can continually be addedto systems.HSM is essentially the automatic movement ofdata between media, the media type useddepending on when it was last accessed. Manysoftware and hardware vendors have HSMsolutions, and all are based on the same basictechniques.The most common HSM setup is where there'sonline storage (the hard disk), near-line storage(some sort of fast media from where a file can bequickly retrieved), and offline storage (slowermedia that might take some time for files to berecovered, but it is cheaper for a long-termstorage). This arrangement is the major thrust oftoday's systems. Most of the time these systemswill comprise optical media for near-line andtape media for offline storage.Data is automatically moved from the onlinedisk to the near-line optical media if it hasn'tbeen accessed for a definable period of time.This is typically three months (depending onyour business).
This near-line system is likely tobe erasable optical disks in some form of jukebox.The system has to operate on the basis that auser won't know that a file has been moved intonear-line storage. Therefore some marker is leftin the directory structure on the disk so that theuser can still see the file. If the user then tries toopen it, the file will automatically be copiedfrom near-line to online storage, and opened forthe user. All the user notices is a slight timedelay while the file is opened.Moving data from near-line to offline storage canbe done using a similar mechanism, but moreoften the marker left in the directory for the userto see will just contain a reference.
This givesthe user the facility to request the file back fromthe systems administrator, and could haveinformation like ' This file has been archived tooffline media' and a reference to the tapenumber that the file is on. This is then sent tothe systems administrator and the file can berecovered from tape in the usual way.Some modern systems have the ability to keepmultiple tapes in a tape changer or jukeboxUNIT 19 Data Security 2system, so retrieval from offline to onlinestorage can be automatic. However, it is morelikely that when a file goes into offline storage itwill never be recovered, as it has probably beenuntouched for several months (again dependingon the business).
Therefore the requirement torecover from offline to online is reasonablyinfrequent.The choice of storage media type is a crucialaspect of HSM. The cheapest is undoubtedly tape(be it digital, analogue or digital linear), so thistends to be used for offline storage. However,tape has no guarantee of data integrity beyondone or two years, whereas optical systems, suchas CDs, WORMs and MO disks, have much betterdata integrity over a longer period of time.Depending on the precise application, archivingsystems are usually based on the media typethat has the best integrity.
The major supplierswithin the HSM market are totally open about themedia that can be used with their software.Current HSM systems support most hardwaredevices, so you can mix and match media to suitrequirements. Given the fact that media choicedepends on the length of time you want yourdata to remain intact, and also the speed atwhich you want to recover it, the choice formany system managers is as follows.Tape is used for backup systems where largeamounts of data need to be backed up on aregular basis.
Tape is cheap, integrity is goodover the short to medium term, and retrievalfrom a backup can be made acceptable with goodtape storage practices.Near-line storage should be based on erasableoptical disks. This is because access is random,so the access speed to find and retrieve aparticular file needs to be fast, and data integrityis also good.Archiving systems should probably be CD- orWORM-based, as again access speeds are good,media costs are reasonably cheap and,importantly, the integrity of the media over themedium to long term is good.One important thing to remember with archivingsystems is the stored data's format.
The datamight be held perfectly for 10 or 15 years, butwhen you need to get it back, it's essential thatyou maintain appropriate hardware and softwareto enable you to read it.[Adapted from 'Backup HSM and media choice' by Phil Crewe,Tape Backup, PC Magazine, May 1996]0139Re-read the text to find the answers tothese questions.1 Mark each of the following statements withTrue or False:abcdefghIjHard disks are still very expensive.Near-line storage needs to have a quickaccess speed.Near-line storage is usually some form ofjukebox.Offline storage needs to have a fast accessspeed.Users are aware that their files have beenmoved to near-line storage.The movement of files between near-line andonline storage is automatic.The user sometimes has to request filesfrom the systems administrator.Files are frequently recovered from offlinestorage.Tape has much better data integrity thanoptical media.It is usually possible to use whatever mediayou want in an HSM system.UNIT 20INTERVIEWex-hackerSTARTERFind the answers to these questions as quickly as you can.1Which group hacked into Hotmail?2Who was 'The Analyser' and what did he do?3Which hacker was sent to jail for fraud?4What was the effect of the 1996 raid on Scotland Yard?5Which of the cases reported here involved teenagers?6What did hackers do to the Yahoo! website?7What crime was Raphael Gray accused of?Kevin Mitnick is the hackers' hero.
His latestspell in jail was a 46-month sentence for fraudrelating to breaking into the systems of severalmultinational corporations. He was released oncondition that he did not have any contact witha computer.Hotmail, Microsoft's free email service, washacked into last September, exposing thecorrespondence of more than 40m users. A groupcalling itself Hackers Unite posted a Web addresswith details of how to access any Hotmailaccount.
The service was shut down for five hours.In March 2000, a Welsh teenager allegedly stoleinformation from more than 26,000 credit cardaccounts across Britain, the US, Japan, Canadaand Thailand, and published the details on theInternet. FBI agents and British police raidedthe home of Raphael Gray,18, and arrested himand his friend. He has been charged with 10counts of downloading unauthorised information.The UK Department of Trade and Industry hastwice been prey to hackers, once in 1996 andagain in 2000 when a DTI computer wasprogrammed to reroute email.
The Home Officeinvestigated nine cases of hacking last year, one ofwhich was the leaking of a report on a murder. InAugust 1996 hackers ran up a £lm phone bill forScotland Yard but did not access flies.In 1998 Washington revealed that an Israelihacker called 'The Analyser' was responsible for'the most organised attempt to penetrate thePentagon's computer systems'. He turned out tobe Ehud Tenenbaum, 18, who had planted a list ofhis own passwords in the Pentagon system andpassed them to other hackers.In 1997 the son of a fraud squad detectivewalked free from a court in London aftercharges of breaching the security of the US airforce were dropped. Three years earlierMathew Bevan, then 19, and a friend, RichardPryce, 16, used the Internet to gain access toseveral US military bases.
Pryce was fined£1,200 after admitting several other offences.In ] 997 hackers got into the Yahoo! website,replacing the homepage with a ransom notedemanding the release of their hero, KevinMitnick. Unless the demand was met, the notesaid, a virus would be released in all Yahoo!'scomputers. The company dismissed the threatas a hoax, but the 'Free Kevin' slogancontinued to appear on other hijacked sites.Think about these questions before you listen.LISTENING1 How could you hack into a system?2 How could you stop people hacking into a system?Mow listen to Part 1 of the recording to check youranswers to Task 2 and to find the answers to these questions:12345678What was Ralph arrested for?What does he do now?Why does he say people are too trusting?What passwords does he suggest for trying to get into a system?What does a firewall do?What is the advantage of a callback system?To prevent hacking, what sort of passwords should you avoid?What do event logs show?Now listen to Part 2 of the recording and find the answersto these questions:1How did Ralph start thinking about computer security?2How did he find the most senior ID in the American company'ssystem?3According to Ralph, why do people hack?4Why did he and his friend hack?5How did the police find him?6 Why does he say companies should use his services?7Do hackers know each other?8What's the difference between Hollywood hackers and the realworld?9How risky is credit card use on the Internet?10What advice does he give for people intending to use creditcards over the Internet?142UNIT 20 The ex-hackerNow listen to both parts again to find the answers tothese questions:12345678What evidence did Ralph and his friend leave to show that theyhad hacked into the American company's system?What is a 'white hat' hacker?What two ways does Ralph give for hacking into a system?What terms does Ralph use to describe someone obsessed bycomputers?How does he maintain contact with the policeman who arrestedhim?How does he describe his lack of enthusiasm for the Hollywoodhacker?What does he mean by 'It's the retailers who get done'?What's the problem with using smart cards for Internetpurchases?LANGUAGE WORKA phrasal verb is a verb + prepositioncombination.
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