‫جلسه هشتم‬
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‫‪‬‬
‫اولين ابزار ذخيره سازي اطالعات بصورت مغناطيس ي در سال ‪ 1978‬توسط‬
‫شرکت ‪ Seagate‬تحت استاندارد ‪ ST506‬به بازار عرضه کرد‪ .‬اين‬
‫استاندارد بالفاصله ويرايش و عنوان ‪ ESDI‬به خود گرفت‪.‬‬
‫ويژگي هاي اين دو استاندارد‪:‬‬
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‫بورد کنترلر ابزار از آن جدا بوده و بصورت يک کارت در اسالتها نصب مي شود‪.‬‬
‫ارتباط ابزار با بورد کنترلر از طريق دو کابل ‪ 20‬و ‪ 34‬پين (سيم) برقرار مي شود‬
‫هر بورد کنترلر حداکثر دو ابزار را پشتيباني مي کند‪.‬‬
‫ظرفيت اين گونه ابزارها و سرعت خواندن و نوشتن آن پايين است‬
‫وابستگي مستقيم به اطالعات حافظه باياس مادربورد‬
‫زمانهاي دستيابي بسيارباال‬
‫استفاده از موتورهاي پله اي براي حرکت‬
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‫سال ‪ 1986‬استاندارد جديد ‪ )Integrated Drive Electronics( IDE‬که اسم‬
‫واقعيتر آن ‪ )AT Attachment( ATA‬است به بازار عرضه شد‪ .‬تکنولوژي غالب‬
‫بوده و در سه نسخه ‪ MCA 16Bit – XT 8Bit – AT 16Bit‬عرضه شد که‬
‫امروزه فقط ‪ AT‬در مادربوردها موجود است‪.‬‬
‫ويژگيها‪:‬‬
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‫بورد اينترفيس يا کنترلر بر روي خود ابزار است‬
‫ارتباط ابزار يا کنترلر ابزار با مادربورد از طريق يک کابل ‪ 40‬رشته يا جديدا ‪ 80‬رشته‬
‫هر اينترفيس از دو ابزار پشتيباني مي کند‪.‬‬
‫وابستگي مستقيم به اطالعات حافظه باياس مادربورد‬
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‫‪ – 96-1986 :ATA-1‬سرعت ‪ 8.33‬مگابايت در ثانيه‬
‫‪:ATA-2‬قابليت اتصال ابزارهاي ديگر را دارد‪ .‬ظرفيت باالي ‪)EIDE(GB137‬‬
‫‪ :ATA-3‬استفاده از قابليت ‪S.M.A.R.T.‬‬
‫‪ :ATA-4‬داراي قابليت ‪)UDMA/33( ATA Packet Interface‬‬
‫‪ :ATA-5‬حداکثر سرعت ‪66‬مگابايت(‪80‬رشته) و ‪ 40‬رشته سيم‪)UDMA/66( .‬‬
‫‪ :ATA-6‬براي ‪ P4‬و‪ PIII‬بود و تا ‪ 100‬مگابايت سرعت دارد(‪)PB144‬‬
‫(‪)UDMA/100‬‬
‫‪ : ATA-7‬براي ‪ P4‬طراحي شد و تا ‪ 133‬مگابايت سرعت دارد‪)UDMA/133( .‬‬
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‫محدوديتهاي ظرفيت درايوها (‪ )CHS - LBA‬مربوط به باياس و استاندارد‬
‫است‪ .‬مثال در باياس وقفه ‪ 1024 – 13‬سيلندر‪ 256 ،‬هد و ‪ 63‬سکتور پشتيباني‬
‫مي کند‪ .‬در حالي که استاندارد از ‪65536‬سيلندر‪16 ،‬هد و ‪255‬سکتور پشتيباني‬
‫مي کند‬
‫حذف مانع ظرفيت ‪ 8.4‬گيگابايت (‪ 98‬به بعد تا ‪ 264‬بايت) به کمک‬
‫تکنولوژي ‪ EDD‬شرکت فونيکس در سال ‪ 98‬استاندارد شد‪.‬‬
‫انتقال سريعتر اطالعات‪ :‬به کمک ‪ PIO‬مدهاي ‪ 0‬تا ‪- 4‬‬
‫مدهاي انتقال ‪ :DMA‬دونوع ‪ DMA‬و ‪Bus Mastering DMA‬‬
‫استاندارد ‪ : ATA Packet Interface‬براي پشتيباني از ابزارهاي‬
‫مختلف مانند درايوهاي ‪ ،CD/DVD‬درايو ‪ ، ZIP‬درايوهاي‪، Jaz‬‬
‫ديسکهاي‪ LS120‬و ‪...‬‬
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‫يک استاندارد براي انتقال سرعت باالست که در سال ‪ 2002‬براي سيستمهاي با ‪ ATA‬سريال‪ ،‬درايوها و‬
‫کارتهاي داخلي به وجود آمدند‪.‬‬
‫به جاي ‪ 40‬و ‪ ،80‬تعداد ‪ 7‬رشته رسيم دارد‪.‬‬
‫داراي سه مد انتقال ‪ 300-150‬و ‪ 600‬مگابايت در ثانيه‬
‫تفاوتهاي آن با ‪:ATA‬‬
‫◦ عدم نياز به جامپر براي انتخاب مستر و اسليو‬
‫◦ حداکثر طول کابل ‪1‬متر( قبلي کمتر از ‪ 0.5‬متر بوده است)‬
‫◦ کانکتور برق ‪ 4‬يا ‪ 15‬پين( اختياري) به صورت استاندارد صنعتي‬
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‫توجه به نوع کابل‬
‫توجه به نوع وسيله و ‪ Master‬يا ‪ Slave‬بودن آن(ست کردن آن)‬
‫اگر کابل ‪80‬رشته اي است از حالت ‪ CS‬استفاده نکنيد‬
‫دقت در نصب کابلها و توجه محل نصب آنها‬
‫سيم قرمز کابل ‪ IDE‬به سمت کابل برق باشد‬
‫تنظيم شناسايي ‪ IDE‬ها بصورت ‪ Auto‬توصيه مي شود‪.‬‬
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‫تعريف هارد‪ :‬يکي از مهمترين قطعات براي نگهداري اطالعات بصورت دائم است‪.‬‬
‫يک هارد از ‪:‬‬
‫‪‬‬
‫‪ 25‬سال از عمر آنها مي گذرد‪.‬‬
‫ظرفيتهاي اوليه در حدود ‪ 10‬تا‪ 30‬مگابايت بوده اما امروز مرز ترابايت را ردکرده‬
‫سرعت انتقال از ‪ 85‬کيلو به ‪ 1‬گيگا رسيده است‬
‫قيمت از ‪ 150‬سنت به کمتر از يک سنت به ازاي يک مگابايت‬
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‫بورد کنترلر‬
‫هدهاي خواندن و نوشتن‬
‫بازوي هدها‬
‫موتور چرخاننده بازوها‬
‫صفحات دايره هاي که اطالعات بر روي آنها نوشته مي شود‪.‬‬
‫بدنه فلزي‬
‫کاور‬
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Information is recorded in a circular fashion in what are
called tracks.
A cylinder is a vertical stack of tracks on multiple
platters..
Tracks are divided into sectors.
A cluster is the smallest unit that DOS uses to store
information (also called an Allocation Unit).
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‫فرمت کردن ‪:‬‬
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‫پارتيشن بندي‬
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‫صفحات هارد ديسک (‪ 3.5‬و ‪2.5‬اينچ) امروزه اغلب ‪ 2‬صفحه هستند‬
‫هدهاي خواندن و نوشتن‬
‫مکانيزم حرکت (سرعت –عدم حساسيت به گرما‪ -‬دقت در موقعيت – عدم لرزش)‬
‫◦ فيزيکي‬
‫◦ منطقي‬
‫◦ ‪ : Fat 16‬حداکثر ‪ 2‬گيگابايت‬
‫◦ ‪ : Fat 32‬حداکثر ‪ 2‬ترابايت‬
‫◦ ‪ :NTFS‬اندازه فضا و فضاي براي ذخيره سازي فايلها‬
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‫◦ موتور پله اي – حرکت با مقدار ثابت ‪ -‬توقف در وسط گام ميسر نيست‪ -.‬در چاپگر – فالپي و‪ ....‬کاربرد دارد‪.‬‬
‫◦ حرکت حلقه صوتي‪ :‬براي سرعتهاي باال و چگالي فشرده – بر اساس نيروي الکترومغناطيس کار مي کند‪ .‬وجود فيدبک از محل هد‬
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‫مکانيزم سروو (مجزا ‪ -‬مخفي – اختصاص ي)‬
‫پارک اتومات هدها‬
‫فيلترهاي هوا‬
‫موتورهاي اسپيندل‬
‫بوردهاي منطقي‪ :‬براي کنترل موتور اسپيندل – سيستم حرکت هدها و خواندن و نوشتن و مديريت اطالعات‪.‬‬
‫کابلها و کانکتورها ‪ :‬کانکتور برق – کانکتور رابط اطالعات‬
1.
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2.
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3.
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Low level formatting (LLF)
This is the "true" formatting process for the disk.
It creates the physical structures (tracks, sectors, control
information) on the hard disk.
Normally, this step begins with the hard disk platters
"clean", containing no information.
Partitioning
This process divides the disk into logical "pieces" that
become different hard disk volumes (drive letters).
This is an operating system function.
High level formatting (HLF)
This final step is also an operating-system-level command.
It defines the logical structures on the partition and places
at the start of the disk any necessary operating system
files.
event that happens when the surface of the
read/write head or particles on its surface
come into contact with the surface of the
hard-disk platter, causing the loss of some or
all of the data on the disk
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‫قابليت اعتماد – ‪ MTBF‬بين ‪ 300000‬تا ‪ 800000‬ساعت است‪.‬‬
‫‪ :SMART‬دادن اخطار قبل از يروز بحران‬
‫بازدهي‪ :‬زمان جستجوي اطالعات بر حسب ميلي و زمان انتقال از يک سيلندر به‬
‫سيلندر ديگر است‪ .‬نرخ انتقال اطالعات‬
‫نرخ انتقال‪( :‬سکتور در هر ترک * ‪ * 512‬دور در دقيقه )بخش بر (‪ 60‬ثانيه)‬
‫زمان دسترس ي متوسط ‪ :‬زماني که به يک سکتور دست پيدا کنيم و برابر نصف‬
‫زمان چرخش ديسک است‪.‬‬
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‫‪Small Computer System Interface‬‬
‫مستقل از مادربورد‬
‫داشتن آداپتور ميزبان‬
‫پشتيباني اسکازي از چند دستگاه‬
‫سرعت انتقال باال‬
‫قابليت پشتيباني از ابزارهاي مختلف‬
‫اتصال ابزراهاي خارج از کيس‬
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The primary disk used for mass storage is the hard
disk drive.
Hard disks differ by technology, interface, speed, and
capacity.
Most are capable of at least 5,000 revolutions per
minute (RPM).
The first PC hard disks
◦ a capacity of 10 megabytes
◦ $100 per MB

Modern hard disks
◦ 100 gigabytes
◦ Less than 1 cent per MB!
◦ improvement of 1,000,000% in just under 20 years, or
around 67% cumulative improvement per year.
Bits on disk - dark stripes are 0 bits
and bright stripes are 1 bits
average
transfer
time

1

2 number
latency

1
1

2 rotational
speed
1
of sectors
 rotational
speed
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Removable hard drives
◦ Hot swap

Disk Arrays
◦ RAID (redundant array of inexpensive disk)
 Mirrored array (fault-tolerant)
 Striped array

AT Attachment
◦ a disk drive implementation that integrates the
controller on the disk drive itself.
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

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ATA and IDE are the same thing, with an interface
that is 16 bits wide to match the old AT bus.
The specification calls for a single channel, shared
by two devices that are configured as master and
slave.
ATA includes support for PIO modes 0, 1 and 2
ATA includes support for single word DMA modes 0,
1 and 2, and multiword DMA mode 0.
The only practical difference is that the PC will
assign drive letters to the master drive
before the slave drive, so that if you have a
master and slave on the primary IDE
channel and each has only one regular,
primary partition, the master will be "C:"
and the slave "D:". This means that the
master drive (on the primary channel) is the
one that is booted, and not the slave.

A newer version of the IDE mass storage device
interface standard developed by Western Digital
Corporation.
◦ It supports data rates of between 4 and 16.6 MBps,
about three to four times faster than the old IDE
standard.


It can support mass storage devices of up to 8.4
gigabytes, whereas the old standard was limited to
528 MB. Because of its lower cost, enhanced EIDE
has replaced SCSI in many areas.
EIDE is sometimes referred to as Fast ATA or Fast
IDE, which is essentially the same standard,
developed and promoted by Seagate Technologies. It
is also sometimes called ATA-2.
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
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ATA-2: Supports faster PIO modes (3 and 4)
and multiword DMA modes (1 and 2). Also
supports logical block addressing (LBA) and
block transfers.
ATA-2 is marketed as Fast ATA and
Enhanced IDE (EIDE).
PIO Mode 3
11.1 MB/s
PIO Mode 4
16.6 MB/s
DMA Multiword 1
13.3 MB/s
DMA Multiword 2
16.6 MB/s
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
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The newest version of the AT Attachment (ATA) standard,
which supports burst mode data transfer rates of 33.3
MBps.
To take advantage of these high speeds, your computer
must also be equipped with Ultra DMA, a protocol that
supports faster data transfer rates to and from hard disk
drives.
UDMA is a more advanced technology which provides for
even faster throughput, up to 33.3 MB/s in UDMA mode 2
and 66.7 MB/s in UDMA mode 4, twice to four times that of
EIDE, for much lower prices than SCSI. Many new
computers come with large UDMA drives and UDMA
interfaces, and it's possible to add a UDMA interface card
(such as the Promise Ultra33 or Ultra66) to an existing
system to boost speed, even on older non-UDMA drives.
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
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Logical Block Addressing
A method used with SCSI and IDE disk drives to
translate the cylinder, head, and sector specifications
of the drive into addresses that can be used by an
enhanced BIOS.
LBA is used with drive's that are larger than 528
MB, and require an enhance BIOS that can handle
LBA.
Logical Block Addressing (LBA) is used to
allow DOS and Windows to use drives over
504MB.



Small Computer Systems
Interface, a standard
developed by the American
National Standards Institute
(ANSI).
It specifies a universal,
parallel, system-level interface
for connecting up to eight
devices (including the
controller) on a single shared
cable (called a SCSI bus).
A SCSI device can install on
any SCSI bus, whether on a
Mac, PC, or any computer with
a SCSI adapter.






SCSI-1: Uses an 8-bit bus, and supports data rates of 4 MBps
SCSI-2: Same as SCSI-1, but uses a 50-pin connector instead of
a 25-pin connector, and supports multiple devices. This is what
most people mean when they refer to plain SCSI.
Wide SCSI: Uses a wider cable (168 cable lines to 68 pins) to
support 16-bit transfers.
Fast SCSI: Uses an 8-bit bus, but doubles the clock rate to
support data rates of 10 MBps.
Fast Wide SCSI: Uses a 16-bit bus and supports data rates of 20
MBps.
Ultra SCSI: Uses an 8-bit bus, and supports data rates of 20
MBps.





SCSI-3: Uses a 16-bit bus and supports data
rates of 40 MBps. Also called Ultra Wide SCSI.
Ultra2 SCSI: Uses an 8-bit bus and supports
data rates of 40 MBps.
Wide Ultra2 SCSI: Uses a 16-bit bus and
supports data rates of 80 MBps.
Ultra320 SCSI : maximum throughput of
320MB/s using 80 MHz bus signaling




Remember that the SCSI specification allows devices
other than a hard drive to be connected to the same
cable, both internally and externally
The host adapter and every device must have a SCSI ID
number between 0 and 7.
Usually, the host adapter is factory set at 7, the
highest priority ID.
The cable must be terminated at both ends (the host
adapter probably is self-terminating, and is commonly
placed at one end. Make sure the termination is
enabled. If the adapter is in the middle, you will need
terminators at both ends.)
1.
◦
◦
◦
2.
◦
◦
3.
◦
◦
Low level formatting (LLF)
This is the "true" formatting process for the disk.
It creates the physical structures (tracks, sectors, control
information) on the hard disk.
Normally, this step begins with the hard disk platters
"clean", containing no information.
Partitioning
This process divides the disk into logical "pieces" that
become different hard disk volumes (drive letters).
This is an operating system function.
High level formatting (HLF)
This final step is also an operating-system-level command.
It defines the logical structures on the partition and places
at the start of the disk any necessary operating system
files.

Redundant Arrays of Inexpensive Disks
◦ use of multiple hard disk drives in an array that
behaves in most respects like a single large

increased capacity, performance and reliability
◦ but they come with real costs.Nothing in life is free.
◦
Self-Monitoring Analysis and Reporting
Technology
