Storage Devices-Hard Disk Drives <<
Previous Next >> Storage Devices- Hot Swapping
Storage Devices-Drive Interfaces
Computers require several things to function well: a method to receive data input, a method to process data, a way to output data, and a way to store data. Data storage has evolved over the years, but the most common storage mechanism, the hard disk, has been around for more than 35 years. The only real change has been in physical size (they have gotten smaller), logical size (they can store much more data), speed, and connector types. The most common types of connectors are SATA, PATA/IDE, SCSI, floppy, eSATA, FireWire, USB, and network connections, each of which we will discuss.
PATA (Parallel Advanced Technology Attachment) has been around since the 1980s, but used to be called IDE (Integrated Drive Electronics). This type of connector uses a cable made up of 40 wires or 80 wires (which supported cable select mode). Both types of cables had 40 pins on each end. The newer-style cables were color-coded, so that the blue connector attached to the motherboard, the black connector attached to the primary (or master) device, and the gray connector attached to the secondary (or slave) device. This connector type was used for hard disk drives, CD drives, DVD drives, and some tape backup drives. Each of these devices has a jumper on it that must be set to “master,” “slave,” or “cable select” mode. “Cable select” eliminated the need to manually assign the master or slave. Each cable could support up to two devices, but only one master or slave device could be used on each cable. The BIOS had to be configured properly before using these devices. In spite of improvements to the EIDE interface using Ultra Direct Memory Access (UDMA), Serial ATA (SATA) is not limited to four devices per channel and has much faster access times.
IDE drive. Photo used under CC-BY-NC-ND license from Brian Barnett.
Drive cables. Photo used under CC-BY license from gcg 2009.
SATA is the current connection method used for hard disks and optical drives. It is called serial because only a single device can be attached to each cable, and the data is transmitted in serial fashion (one bit at a time). These devices often do not have jumpers, but if they have one, it is used to configure the speed of data transfer or to enable a special feature like spread spectrum clocking . SATA is a peripheral device and is very fast, allowing for speeds of up to 6 Gbps for the newer version, or 3 Gbps for the older versions. The data cable is shaped like an L, with seven pins for data. The power cable is also L-shaped, but has 15 pins. Internal SATA ports can be converted to an eSATA (external SATA) port simply by using a header to connect the internal port.
SATA drive. Photo used under CC-BY license from Arkadiusz Sikorski.
SCSI, or small computer system interface, supports daisy-chaining of devices (internally or externally) with either seven devices (narrow SCSI) or 15 devices (wide SCSI). Each device in the chain is provided with a Device ID number that is configured using a selector switch, DIP (dual inline package) switch, or jumper block. SCSI is an older technology and has largely been replaced by SATA and eSATA. Narrow SCSI could only support speeds of up to 40 MBps, while wide SCSI could support up to 320 MBps.
HP Surestore DAT-drive with two blue SCSI ports on the back. Photo used under CC-BY-SA license from Gerben Wierda.
計算機需要幾件事情才能正常運行:一種接收數據輸入的方法,一種處理數據的方法,一種輸出數據的方法以及一種存儲數據的方法。數據存儲已經發展了多年,但是最常見的存儲機制硬盤已經存在了35年以上。唯一真正的變化是物理大小(變得更小),邏輯大小(它們可以存儲更多數據),速度和連接器類型。連接器最常見的類型是SATA,PATA / IDE,SCSI,軟盤,eSATA,FireWire,USB和網絡連接,我們將分別討論它們。
PATA(並行高級技術附件)自1980年代就出現了,但以前被稱為IDE(集成驅動電子設備)。這種類型的連接器使用由40線或80線組成的電纜(支持電纜選擇模式)。兩種類型的電纜的每端都有40個插針。較新樣式的電纜已進行顏色編碼,因此藍色連接器連接至主板,黑色連接器連接至主(或主)設備,灰色連接器連接至輔助(或從屬)設備。此連接器類型用於硬盤驅動器,CD驅動器,DVD驅動器和某些磁帶備份驅動器。這些設備中的每一個都有跳線,必須將其設置為“主”,“從”或“電纜選擇”模式。“電纜選擇”消除了手動分配主機或從機的需要。每條電纜最多可支持兩個設備,但是每條電纜上只能使用一個主設備或從設備。使用這些設備之前,必須正確配置BIOS。儘管使用超直接內存訪問(UDMA)對EIDE接口進行了改進,但串行ATA(SATA)不僅限於每個通道四個設備,而且訪問速度更快。
IDE驅動器。照片由Brian Barnett根據CC-BY-NC-ND許可使用。
驅動器電纜。照片由gcg 2009根據CC-BY許可使用。
SATA是用於硬盤和光盤驅動器的當前連接方法。之所以稱為串行,是因為每條電纜只能連接一個設備,並且數據以串行方式(一次一位)傳輸。這些設備通常沒有跳線,但如果有跳線,則可用於配置數據傳輸速度或啟用特殊功能,例如 擴頻時鐘。SATA是外圍設備,速度非常快,新版本的速度高達6 Gbps,而舊版本的速度高達3 Gbps。數據電纜的形狀像L形,有七個數據針。電源線也為L形,但有15針。只需使用接頭連接內部端口,即可將內部SATA端口轉換為eSATA(外部SATA)端口。
SATA驅動器。照片由Arkadiusz Sikorski根據CC-BY許可使用。
CSI或小型計算機系統接口支持將設備(內部或外部)與7個設備(窄SCSI)或15個設備(寬SCSI)進行菊花鏈連接。鏈中的每個設備都提供了一個設備ID編號,該ID使用選擇器開關,DIP(雙列直插式封裝)開關或跳線塊進行配置。SCSI是一種較舊的技術,在很大程度上已被SATA和eSATA取代。窄SCSI只能支持高達40 MBps的速度,而寬SCSI可以支持高達320 MBps的速度。
HP Surestore DAT驅動器,背面有兩個藍色SCSI端口。圖片由Gerben Wierda根據CC-BY-SA許可使用。
Storage Devices-Hard Disk Drives <<
Previous Next >> Storage Devices- Hot Swapping