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What is the difference between USB3.0 and USB2.0?



USB3.0 transfer rate of USB 2.0 times USB2.0 rate of 480Mbps, while USB 3.0 can reach 5.0Gbps greatly improve the efficiency of data transmission. And USB2.0 USB 3.0 will be more energy efficient. In addition, USB 3.0 is backward compatible to support USB 2.0 devices. USB 3.0 is compatible with earlier versions of the standard to support general-purpose I / O interface, and will be optimized to reduce energy consumption, while improving the efficiency of the products of the field of computer, consumer products and mobile products protocol support for fast synchronization ability to move simultaneously support for optical and digital components specification, and with legacy USB technology ease of use and plug and play-to-use features.
Mini USB 3.0 interface will be divided into A, B both male (Plug) and female (Receptacle) B and AB, AB female shape is compatible with A and B, two male you can see the 3.0 version of the male pin 9-pin, 2.0 5-pin for backwards compatibility with version 2.0, USB 3.0 uses a 9-pin design, with four-pin and USB 2.0 shape, definitions are fully the same, while the other five are prepared specifically for USB 3.0.

如何 理解 磁盘 阵列 (RAID) 中 的 RAID 0, RAID 0 +1, RAID 1, RAID 2, RAID 3, RAID 4?



RAID 0: RAID 0 continuous segmentation data bit or byte parallel read / write to multiple disks, and therefore has a high data transfer rate, but it has no data redundancy, and therefore can not be considered a true RAID structure . RAID 0 is simply to improve performance, and did not provide a guarantee for the reliability of data, and a disk failure will affect all of the data. Therefore, RAID 0 can not be applied to the data security requirements of the occasion.

RAID 1: disk data mirroring for data redundancy, mutual backup of the data in pairs of independent disks. Peak raw data can be directly read from the mirrored copy of data, RAID 1 can improve read performance. RAID 1 is the highest unit cost of the disk array, but provides a high level of data security and availability. When a disk fails, the system can automatically switch to the mirrored disk read and write, without the need for reorganization of failure data.

RAID 0 +1: also known as RAID 10 standard, the actual product of the combination of RAID 0 and RAID 1 standard, the continuous bit or byte partitioning the data and parallel read / write multiple disks at the same time, in order to a disk for disk mirroring for redundancy. Its advantage is to have both the extraordinary speed of RAID 0 and RAID 1 data of high reliability, but the CPU utilization rate is also higher, and disk utilization is relatively low.

RAID 2: compartmentalization of data distributed on different drives, compartmentalized units of bits or bytes, and use known as "increase the average error-correcting codes (Hamming codes) coding techniques provide error checking and recovery. This encoding technology requires more disk storage inspection and recovery information, RAID technology implementation more complex, and therefore rarely used in a commercial environment.

RAID 3: RAID 2, it is very similar, data compartmentalization are located on different drives, the difference is that RAID 3 uses a simple parity, and single disks to store parity information. If a disk fails, the parity disk and data disk can reproduce the data; If the parity disk failure did not affect the data. RAID 3 for a large number of continuous data transmission rate, but for random data, the parity disk will become the bottleneck of the write operation.

RAID 4: RAID 4 also data compartmentalization and distributed in a different disk, but the bar unit block or record. RAID 4 to use a disk to disk as parity, each write operation needs to access the parity disk, then the parity disk will become the bottleneck of the write operation, RAID 4 is rarely used in a commercial environment.

如何 理解 和 eSATA SATA?



的 全称 是 eSATA External Serial ATA (外部 串行 ATA), SATA 它 是 接口 的 外部 扩展 → SATA eSATA / USB 直接 将 大 硬盘 外置 规范.

In other words, eSATA is the external version of SATA, it is used to connect an external rather than internal SATA devices. For example, has an eSATA port, you can easily connect the SATA hard drive and motherboard eSATA interface without having to open the case to replace the SATA hard drive. SATA interface, eSATA some changes in the hardware specifications, data cable interface connections fitted with metal shrapnel to ensure a solid physical connection. The original SATA L-shaped plug direction of the difference between the interface, while eSATA is to prevent mistakenly inserted through the plug top and bottom of different thickness and groove, and it also supports hot-swappable. Although the interface mode is changed, but the the eSATA underlying physical specification has not changed, still using the 7-pin data cable, so only need to change the interface will be able to achieve compatibility of SATA devices. The SATA interface is L-shaped, eSATA interface, is in flat 3.5-inch drives maximum data transfer rate of 60MB / s in the external 3.5-inch HDD Enclosure, USB 2.0 or IEEE 1394 interface speed data transmission bottleneck. If you use an external RAID 0 storage devices, interface bandwidth of up to 480Mbps and will seriously limit the performance of the hard drive to play. Therefore, eSATA is a very good solution. ESATA hard drive box with a SATA hard drive, in the middle without bridge chip conversion, is a native storage device interface.


What is NAS?



NAS (Network Attached Storage: Network Attached Storage) is a distribution of independent data integration for large-scale, centralized management of data centers, in order to access the technology on different hosts and application servers. Literally it simply is connected to the network, with data storage capabilities of the device, also known as "network memory". It is a dedicated data storage server. It is data-centric, the complete separation of the storage devices and servers, and centralized management of data, freeing bandwidth and improve performance, reduce total cost of ownership, investment protection.

Windows XP recognized 3TB of removable hard disk?



For hard disk larger than 2TB, the following three conditions:
initialized to MBR mode, you can only identify 2.16T.
If initialized to GPT mode, XP is unable to its operation, but the Win7 able to identify and use the full capacity.
Load a particular patch, use the full capacity in XP.