5.4.2The Write Channel

The signal path for the Write Channel follows the reverse order of that for the Read Channel. The host transmits data via the AT bus to the 88i9422 Interface Controller. The Buffer Controller section of the 88i9422 stores the data in the cache. Because the data is transmitted to the drive at a rate that exceeds the rate at which the drive can write data to the disk, data is stored temporarily in the cache. Thus, the host can present data to the drive at a rate independent of the rate at which the drive can write data to the disk.

Upon correct identification of the target address, the data is shifted to the Sequencer, which generates and appends an error correcting code. The Sequencer then converts the bytes of data to a serial bit stream. The AT controller also generates a preamble field, inserts an address mark, and transmits the data to the ENDEC in the R/W IC where the data is encoded into the LDPC format and pre-compensates for non-linear transition shift. The amount of write current is set by the 88i9422 DSP and Interface/Disk Controller through the serial interface to the preamplifier.

The 88i9422 switches the Preamplifier and Write Driver IC to write mode and selects a head. Once the Preamplifier and Write Driver IC receive a write gate signal, it transmits current reversals to the head, which writes magnetic transitions on the disk.

5.5 Firmware Features

This section describes the following firmware features:

Read Caching

Write Caching

Track Skewing

Defect Management

Automatic Defect Allocation

ECC Correction

SMART (Self-monitoring and reporting technology)

ATA security mode features

ATA host protected area

ATA streaming features

ATA power up in stand by feature set

ATA advanced power management (APM) feature set

ATA device configuration overlay (DCO) feature set

5.5.1Read Caching

The Spinpoint M8 hard disk drive uses Read Cache to enhance drive performance and significantly improve system throughput. Use the SET FEATURES command to enable or disable Read Caching. Read caching anticipates host-system requests for data and stores that data for faster future access. When the host requests a certain segment of data, the cache feature utilizes a prefetch strategy to get the data in advance and automatically read and store the following data from the disk into fast RAM. If the host requests this data, the RAM is accessed rather than the disk.

There is a high probability that subsequent data requested will be in the cache, because more than 50 percent of all disk requests are sequential. It takes microseconds rather than milliseconds to retrieve this cached data. Thus Read Caching can provide substantial time savings during at least half of all disk requests. For example, Read Caching

Spinpoint M8-DVR Disti Product Manual REV 2.0

32

Page 38
Image 38
Samsung M8-DVR manual Firmware Features, Write Channel, Read Caching

M8-DVR specifications

The Samsung M8-DVR is an advanced digital video recorder designed to meet the ever-evolving demands of modern surveillance and recording needs. This cutting-edge device combines state-of-the-art technology with user-friendly features, making it a reliable choice for both residential and commercial applications.

At the core of the M8-DVR’s design is its high-definition recording capability. The device supports various resolutions, including Full HD 1080p, ensuring that all captured footage is crystal clear. This clarity is crucial for identifying details, whether for security purposes or monitoring activities around the clock. It can accommodate multiple camera inputs, allowing users to expand their surveillance network seamlessly.

One of the standout features of the M8-DVR is its remarkable storage capacity. Equipped with advanced hard disk technology, it can store several terabytes of footage, which can be further expanded using additional drives. This means that even with continuous recording, users won’t have to worry about running out of storage quickly. The device also incorporates efficient compression technologies, such as H.265, which allows for reduced file sizes without sacrificing video quality.

In terms of connectivity, the M8-DVR offers various options, including Ethernet ports for network connectivity, USB ports for data transfer, and HDMI output for direct connection to monitors. This versatility allows users to easily stream live footage or review recordings on larger screens. The device supports remote viewing through mobile applications, allowing users to monitor their property from virtually anywhere in real-time.

User experience is further enhanced by an intuitive interface that makes navigation simple and efficient. It includes features like motion detection and alerts, which notify users of any unusual activities. The advanced search function is another highlight, enabling users to quickly locate specific events in their recordings without long hours of scrolling.

The Samsung M8-DVR is also designed with durability in mind. It comes with robust security features to protect against unauthorized access and offers backup options to prevent data loss. With its blend of technology, storage capabilities, and user-friendly design, the Samsung M8-DVR stands out as a comprehensive solution for modern video surveillance needs, making it an essential tool for enhancing security and peace of mind in any environment.