Samsung SP0211N Service Manual page 23

SAMSUNG HARD DISK DRIVE
2) The logical mechanism of hard disk
Hard disk consists of boot record, FAT, root directory, data field.
① Boot Record: Boot record is consists of sector 1, track 0, side 0.
Boot record is the one of most important parts. It has some information about the physical
structure of disk. If boot record is vanished, the disk is useless entirely.
The physical information mean, for example, the number of FAT, capacity of disk something
like that. Also has boot record also contains programs to make work the operating systems.
The program which is capable of working the operating systems is the definition containing
several specific information like the number of byte per sector, the total of sectors in disk.
② FAT: It says that quota information field: that is the memory field about where the file is
located in real data field. Just like we are known the rooms occupied or empty by a hotel
account book. Most files occupy several cluster not just one cluster. Cluster belong to a
files is scattered in many parts on disk, not existing constantly. If cluster is vanished
or destroyed, we don't know the linking state. So we can't read files properly.
③ Root Directory: All of disk have only one root directory. Root directory exist certainly
whether sub directory exist or not. Root directory is the memory field which remember the
files on disk and the list of sub directory. And sub directory is treated as files in root
directory. Using the disk is restricted when root directory is damaged like as file quota table.
3) Terms about hard disk
① Seek Time: Seek time is referred to the time that head in disk takes to located a particular
piece of data which has information the head want to read. Disk speed is getting faster
according to seek time speed. Strictly speaking, seek time of track vs track tell the more
accurate disk speed. Seek time of track vs track refer to the time that the disk head which is
in present location move to the just next side of sector of track.
② Access Time: The access time for disk drives includes the time it actually takes for the
read/write head to locate a sector on the disk (called the seek time). For example, the last
read head located on track 3 and the next information is located on track 4,the time to try
want read(access time) is the same for a seek time of track vs track. But we are not sure the
location of the next information we regard this as a average time. This is an average time
since it depends on how far away the head is from the desired data, it is similar to a time
that head takes to spin a half of the whole track.
④ Latency: In general, the period of time passing through the unreadable region.
Its time is similar to passing time across the half of hard disk circle.
⑤ Inter-Leave: The physical sector numbers among the continuous sectors logically on disk.
Logical sector is not corresponding to that of physical: the reason is that disk head needs
some time can read next sector from the first sector accepting data. Disk head has to keep
spinning the while. If a data in sector1 and next data in sector 2:1:1 inter-leave,
in sector 3:1:2 inter-leave. 1:1 isn't always efficiency because data of the sector1 receive
from memory then try to receive sector2, if the disk is already spun, need one more spin.
⑥ Partition : The logical region of disk. Normally disk divides logical region into
physical region. The former contains side,track,sector and the latter contains partition.
In dos systems, you can partition a disk and each partition will behave like a separate
disk drive.Dos recognize two sort of partitions.
PALO
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