Festplattengeschwindigkeitsfrage

Original geschrieben von Zalman
Das Schreiben fängt von außen nach innen an und ist außen am schnellsten.

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Original geschrieben von MDG
HÖ?

Es wird doch von Innen nach Außen geschrieben!!

Außen sind die Daten allerdings am schnellsten. Darum erreichen auch zB CD-brenner ihre maximalgeschwindigkeit erst am ende!

MDG

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http://www.tecchannel.de/hardware/458/3.html

Die kleinste von außen lesbare Einheit der Festplatte ist ein Sektor. Je nach Formatierung besitzt er eine Länge von 512 (Standard), 1024 oder 4096 Bytes. Die Anordnung der Sektoren besteht aus konzentrischen Datenkreisen. Ein Kreis wird als Spur bezeichnet und von außen nach innen durchnummeriert. Der äußerste Kreis der Magnetplatte ist Spur 0. Alle Spuren sind weiter in die einzelnen Sektoren unterteilt. Um einen bestimmten Sektor zu lesen, muss der Magnetkopf auf die entsprechende Spur positioniert werden und warten, bis der zu lesende Sektor unter dem Kopf vorbeikommt.

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Original geschrieben von sethesh
also wenn ich mich nicht täusche dann schreibt eine festplatte von aussen nach innen, und ist somit auch am "anfang" am schnellsten!

## seth ##

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http://www.pcguide.com/ref/hdd/geom/tracksZBR-c.htmlw

Zoned Bit Recording

One way that capacity and speed have been improved on hard disks over time is by improving the utilization of the larger, outer tracks of the disk. The first hard disks were rather primitive affairs and their controllers couldn't handle complicated arrangements that changed between tracks. As a result, every track had the same number of sectors. The standard for the first hard disks was 17 sectors per track.

Of course, the tracks are concentric circles, and the ones on the outside of the platter are much larger than the ones on the inside--typically double the circumference or more. Since there is a constraint on how tight the inner circles can be packed with bits, they were packed as tight as was practically possible given the state of technology, and then the outer circles were set to use the same number of sectors by reducing their bit density. This means that the outer tracks were greatly underutilized, because in theory they could hold many more sectors given the same linear bit density limitations.

To eliminate this wasted space, modern hard disks employ a technique called zoned bit recording (ZBR), also sometimes called multiple zone recording or even just zone recording. With this technique, tracks are grouped into zones based on their distance from the center of the disk, and each zone is assigned a number of sectors per track. As you move from the innermost part of the disk to the outer edge, you move through different zones, each containing more sectors per track than the one before. This allows for more efficient use of the larger tracks on the outside of the disk.


One interesting side effect of this design is that the raw data transfer rate (sometimes called the media transfer rate) of the disk when reading the outside cylinders is much higher than when reading the inside ones. This is because the outer cylinders contain more data, but the angular velocity of the platters is constant regardless of which track is being read (note that this constant angular velocity is not the case for some technologies, like older CD-ROM drives!) Since hard disks are filled from the outside in, the fastest data transfer occurs when the drive is first used. Sometimes, people benchmark their disks when new, and then many months later, and are surprised to find that the disk is getting slower! In fact, the disk most likely has not changed at all, but the second benchmark may have been run on tracks closer to the middle of the disk. (Fragmentation of the file system can have an impact as well in some cases.)

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