Free Windows Help Tutorials sponsored by inkjet printer cartridges dot org /title> <META HTTP-EQUIV="imagetoolbar" CONTENT="no"> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; CHARSET=ISO 8859-1"> <META name="description" Content="Hundreds of downloadable Windows help tutorials, articles and how-to guides sponsored by inkjet printer cartridges dot org."><style type="text/css">  </style> </head> <body bgcolor=#999999 vlink=blue link=blue> <span name = "INTRA" class="pg" style="top:0px; left:5px; width:714px; height:1010px"></span> <span name = "INTRA" style='top:0px; left:5px; height:1010px; width:714px' class='img'> <img src="pg0002im.png" height = "1010 width = "714" border="0"> </span> <span class='nav' style='left: 10px; top: 10px'><pre></pre></span><span name = "INTRA" style='top:48px; left:516px' class="ft2"><pre><font face='Helvetica'>Understanding Drive Technology</font></pre></span> <span name = "INTRA" style='top:88px; left:247px' class="ft0"><pre><font face='Arial'>Disk drives can often be in use for a considerable period of time, and sometimes</font></pre></span> <span name = "INTRA" style='top:101px; left:247px' class="ft0"><pre><font face='Arial'>additional storage is added rather than replacing the drive. The problem with</font></pre></span> <span name = "INTRA" style='top:114px; left:247px' class="ft0"><pre><font face='Arial'>replacement is that it necessitates complete reinstallation of operating systems and</font></pre></span> <span name = "INTRA" style='top:127px; left:247px' class="ft0"><pre><font face='Arial'>applications, which means you also need to back up and restore the data.</font></pre></span> <span name = "INTRA" style='top:147px; left:247px' class="ft0"><pre><font face='Arial'>1983 saw the introduction of the hard disk as a standard component in the fledgling</font></pre></span> <span name = "INTRA" style='top:160px; left:247px' class="ft0"><pre><font face='Arial'>PC, and comparing those early 5 MB drives to the 60 GB and greater drives of today</font></pre></span> <span name = "INTRA" style='top:172px; left:247px' class="ft0"><pre><font face='Arial'>makes little sense. Although the basic idea has changed little, the way it is imple </font></pre></span> <span name = "INTRA" style='top:185px; left:247px' class="ft0"><pre><font face='Arial'>mented had undergone a radical change. During that entire process the terminology</font></pre></span> <span name = "INTRA" style='top:198px; left:247px' class="ft0"><pre><font face='Arial'>has also changed, and it can almost be a full time task keeping up to date with the</font></pre></span> <span name = "INTRA" style='top:211px; left:247px' class="ft0"><pre><font face='Arial'>latest terms and ensuring that you do understand them. SCSI (Small Computer</font></pre></span> <span name = "INTRA" style='top:223px; left:247px' class="ft0"><pre><font face='Arial'>System Interface) is a perfect example of this, and we will see later how changes</font></pre></span> <span name = "INTRA" style='top:236px; left:247px' class="ft0"><pre><font face='Arial'>here have occurred even before products have been properly agreed through the</font></pre></span> <span name = "INTRA" style='top:249px; left:247px' class="ft0"><pre><font face='Arial'>standards bodies, leading to confusion over what should be implemented in the next</font></pre></span> <span name = "INTRA" style='top:261px; left:247px' class="ft0"><pre><font face='Arial'>generation of computers and servers.</font></pre></span> <span name = "INTRA" style='top:288px; left:247px' class="ft1"><pre><font face='Arial'><i><b>Inside</b></i> <i><b>The</b></i> <i><b>Drive</b></i></font></pre></span> <span name = "INTRA" style='top:310px; left:247px' class="ft0"><pre><font face='Arial'>A hard disk drive is made from a number of flat platters made from aluminium disk</font></pre></span> <span name = "INTRA" style='top:323px; left:247px' class="ft0"><pre><font face='Arial'>substrate or mylar, each side of which is coated with a magnetic material composed</font></pre></span> <span name = "INTRA" style='top:335px; left:247px' class="ft0"><pre><font face='Arial'>of small metallic particles made from either iron oxide or thin film metal media. This</font></pre></span> <span name = "INTRA" style='top:348px; left:247px' class="ft0"><pre><font face='Arial'>material is divided into a number of concentric circles called tracks, and then further</font></pre></span> <span name = "INTRA" style='top:361px; left:247px' class="ft0"><pre><font face='Arial'>sub divided into slices, creating areas known as sectors. If you were to pass a nail</font></pre></span> <span name = "INTRA" style='top:374px; left:247px' class="ft0"><pre><font face='Arial'>through the same sector on all the platters in a disk, you would end up with a</font></pre></span> <span name = "INTRA" style='top:386px; left:247px' class="ft0"><pre><font face='Arial'>cylinder. The data is read and written by means of heads mounted on an actuator</font></pre></span> <span name = "INTRA" style='top:399px; left:247px' class="ft0"><pre><font face='Arial'>arm. One of the key speed improvements over the last fifteen years has been in the</font></pre></span> <span name = "INTRA" style='top:412px; left:247px' class="ft0"><pre><font face='Arial'>performance of the actuator arm and its accuracy in positioning over the data area</font></pre></span> <span name = "INTRA" style='top:424px; left:247px' class="ft0"><pre><font face='Arial'>on the disk.</font></pre></span> <span name = "INTRA" style='top:445px; left:247px' class="ft0"><pre><font face='Arial'>Another element in increasing the performance, and which has also improved the</font></pre></span> <span name = "INTRA" style='top:458px; left:247px' class="ft0"><pre><font face='Arial'>storage capacity, has been the increase in the number of heads on the actuator arm.</font></pre></span> <span name = "INTRA" style='top:470px; left:247px' class="ft0"><pre><font face='Arial'>Early drives used just one head per side, and this led to a number of performance</font></pre></span> <span name = "INTRA" style='top:483px; left:247px' class="ft0"><pre><font face='Arial'>issues. As data became more fragmented over the platter, the head needed to be</font></pre></span> <span name = "INTRA" style='top:496px; left:247px' class="ft0"><pre><font face='Arial'>moved a considerable distance in order to carry out any read or write operation.</font></pre></span> <span name = "INTRA" style='top:508px; left:247px' class="ft0"><pre><font face='Arial'>The early drives were also incapable of reading the data when it was very close to</font></pre></span> <span name = "INTRA" style='top:521px; left:247px' class="ft0"><pre><font face='Arial'>the head without having to rotate the surface to gain an accurate positioning, and</font></pre></span> <span name = "INTRA" style='top:534px; left:247px' class="ft0"><pre><font face='Arial'>this led to wasted effort and a reduction in performance. To reduce this, the data</font></pre></span> <span name = "INTRA" style='top:546px; left:247px' class="ft0"><pre><font face='Arial'>was not written contiguously to the surface, but was spaced out across the sectors.</font></pre></span> <span name = "INTRA" style='top:559px; left:247px' class="ft0"><pre><font face='Arial'>This was often referred to as the interleave factor , with a 3:1 factor indicating the</font></pre></span> <span name = "INTRA" style='top:572px; left:247px' class="ft0"><pre><font face='Arial'>need to rotate the disk three times in order to read the required data. Today's drives</font></pre></span> <span name = "INTRA" style='top:585px; left:247px' class="ft0"><pre><font face='Arial'>all work on a 1:1 ratio and use data buffers, therefore interleave factor is rarely</font></pre></span> <span name = "INTRA" style='top:597px; left:247px' class="ft0"><pre><font face='Arial'>mentioned any more.</font></pre></span> <span name = "INTRA" style='top:624px; left:247px' class="ft1"><pre><font face='Arial'><i><b>Heads</b></i></font></pre></span> <span name = "INTRA" style='top:646px; left:247px' class="ft0"><pre><font face='Arial'>With multiple heads on a single arm, the distance that needed to be traversed was</font></pre></span> <span name = "INTRA" style='top:659px; left:247px' class="ft0"><pre><font face='Arial'>much reduced with the inevitable performance gain. The heads have also been</font></pre></span> <span name = "INTRA" style='top:671px; left:247px' class="ft0"><pre><font face='Arial'>moved closer to the actual platter, and this has had two important benefits. The first</font></pre></span> <span name = "INTRA" style='top:684px; left:247px' class="ft0"><pre><font face='Arial'>is a reduction in the amount of power necessary to read and write, which means</font></pre></span> <span name = "INTRA" style='top:697px; left:247px' class="ft0"><pre><font face='Arial'>disk drives can be smaller, as the amount of heat that needs dissipating is reduced.</font></pre></span> <span name = "INTRA" style='top:710px; left:247px' class="ft0"><pre><font face='Arial'>With the reduction in power requirements we also saw more reliable notebook</font></pre></span> <span name = "INTRA" style='top:722px; left:247px' class="ft0"><pre><font face='Arial'>computers, since as storage power needs reduced, battery life was extended. The</font></pre></span> <span name = "INTRA" style='top:735px; left:247px' class="ft0"><pre><font face='Arial'>second benefit was that the amount of data stored on a platter could be significantly</font></pre></span> <span name = "INTRA" style='top:748px; left:247px' class="ft0"><pre><font face='Arial'>increased, as the heads were smaller and more accurate, and the material coating</font></pre></span> <span name = "INTRA" style='top:749px; left:62px' class="ft3"><pre><font face='Arial'><i> Every</i> <i>hard</i> <i>disk</i> <i>ships</i></font></pre></span> <span name = "INTRA" style='top:760px; left:247px' class="ft0"><pre><font face='Arial'>the platter was much finer than that previously used.</font></pre></span> <span name = "INTRA" style='top:773px; left:62px' class="ft3"><pre><font face='Arial'><i>with</i> <i>a</i> <i>potential</i> <i>storage</i></font></pre></span> <span name = "INTRA" style='top:781px; left:247px' class="ft0"><pre><font face='Arial'>This led to another advance in the way that the data was actually stored on the disk</font></pre></span> <span name = "INTRA" style='top:793px; left:247px' class="ft0"><pre><font face='Arial'>platter. Each track on the platter is further divided into segments, rather like a cake,</font></pre></span> <span name = "INTRA" style='top:797px; left:62px' class="ft3"><pre><font face='Arial'><i>capacity,</i> <i>but</i> <i>formatting</i></font></pre></span> <span name = "INTRA" style='top:806px; left:247px' class="ft0"><pre><font face='Arial'>called sectors. Older drives were very wasteful in the way they created the sectors</font></pre></span> <span name = "INTRA" style='top:819px; left:247px' class="ft0"><pre><font face='Arial'>on the disk because each track was split into an equal number of sectors. This meant</font></pre></span> <span name = "INTRA" style='top:821px; left:62px' class="ft3"><pre><font face='Arial'><i>programs</i> <i>determine</i> <i>how</i></font></pre></span> <span name = "INTRA" style='top:832px; left:247px' class="ft0"><pre><font face='Arial'>that the storage capacity of the disk was constrained by the amount of data that</font></pre></span> <span name = "INTRA" style='top:844px; left:247px' class="ft0"><pre><font face='Arial'>could be stored in a sector at the centre of each platter. This was replaced by a</font></pre></span> <span name = "INTRA" style='top:845px; left:62px' class="ft3"><pre><font face='Arial'><i>much</i> <i>data</i> <i>will</i> <i>be</i> <i>stored</i></font></pre></span> <span name = "INTRA" style='top:857px; left:247px' class="ft0"><pre><font face='Arial'>technique called MZR (Multiple Zone Recording), which takes into account the fact</font></pre></span> <span name = "INTRA" style='top:870px; left:247px' class="ft0"><pre><font face='Arial'>that, as you move out from the centre of a platter, tracks are bigger. By using a fixed</font></pre></span> <span name = "INTRA" style='top:869px; left:62px' class="ft3"><pre><font face='Arial'><i>in</i> <i>any</i> <i>given</i> <i>sector. </i></font></pre></span> <span name = "INTRA" style='top:882px; left:247px' class="ft0"><pre><font face='Arial'>amount of space to indicate the size of a sector, the outer tracks can be split into more</font></pre></span> <span name = "INTRA" style='top:895px; left:247px' class="ft0"><pre><font face='Arial'>sectors than the inner tracks, allowing a more effective use of the drive. There are</font></pre></span> <span name = "INTRA" style='top:950px; left:52px' class="ft2"><pre><font face='Helvetica'>Update 152:July 2001</font></pre></span> <span name = "INTRA" style='top:943px; left:263px' class="ft4"><pre><font face='Arial'><b>PC</b> <b>Support</b> <b>Advisor</b></font></pre></span> <span name = "INTRA" style='top:950px; left:612px' class="ft2"><pre><font face='Helvetica'>File: B1047.2</font></pre></span> <span name = "INTRA" style='top:962px; left:52px' class="ft2"><pre><font face='Helvetica'>page 14</font></pre></span> <span name = "INTRA" style='top:962px; left:518px' class="ft2"><pre><font face='Helvetica'>Buying and Evaluating:Hardware</font></pre></span> <span name = "INTRA" style='top:967px; left:284px' class="ft5"><pre><font face='Helvetica'><b>www.pcsupportadvisor.com</b></font></pre></span> <span name = "INTRA" class='nav' style='left: 357px; top: 1010px'><pre><a href='page0001.htm'><</a> Next page <a href='page0001.htm'>></a></pre></span> <span name = "INTRA" style='top:1050px; left:50px' class="ft4"><pre><b><font color="#FF0000" size="3" face="Arial">New!</font><font color="#FF0000" size="3" face="Arial Narrow"> </font><font size="2" face="Arial">The best sites for quality <a href="http://www.inkjet-printer-cartridges.org">inkjet printer cartridges</a> and the best sites for <a href="http://www.cheap-inkjet-cartridges.com">cheap inkjet cartridges</a></font></b></pre></span></body> <span name = "INTRA" style='top:1100px; left:300px' class="ft4"><pre><b><font color="#FF0000" size="3" face="Arial"><a href="../index.html">Windows Help Desk Home</a> </font></b></pre></span></body></html>