Abstract: Proposed that one kind of new intelligent network floppy disk storage technology, is suitable for the TCP/IP communication network. This technology may solve the storage device simple point expiration problem effectively, enhanced the data turnover rate, easy to expand the disk size. The union inlays eight type technologies the development, discusses the intelligent network floppy disk’s data accessing module software architecture and the key technologies in detail, and through transplants the uCIinux operating system and the development application software on the S3C44BOX development board, realizes the intelligent network floppy disk’s data accessing function.
Key word: Network floppy disk ARM S3C44BOX uClinux
Introduction
In the past’s 20 years, memory system’s development speed has been slow. Although the IDE technology, the SCSI technology’s development has provided the more effective data transmission, the quicker floppy disk actuation and the bigger disk size, but the memory system still takes server’s appurtenance, has not gotten rid of the server/memory system’s pattern, the server simple point expiration and the bottleneck question still exists. The lucky bit ethernet and Fibre the Channel technology’s appearance, causes the server and the memory system takes the coordinated entity to exist in the network becomes possibly, the memory system no longer attaches in the server, server’s expiration cannot cause to the memory system on the data accessing expiration.
So-called intelligent network floppy disk 1ND (Intelligent NetworkDisk), is not the direct company on the personal computer, but through the network interface connection in the network, the user may visit the file data through the file attribute. The intelligent network floppy disk provides the unification to the user the connection, a use Yuan data provides for the user face the set data view. In physics, the identical set’s data possibly distributes on the different intelligent network floppy disk. When memory acts according to the Yuan data determination data the storage location; The response data visit request basis saves Yuan data positioning data concrete storage location, then to user transmission data. The intelligent network floppy disk may divide into the system software and the application software two major parts; System software including TCP/IP agreement stack, filing system, driver and so on several parts. Application software including data accessing module, data positioning module, Yuan data management module and data buffer module and so on. The data accessing module undergoes the virtual file system visit to save on the storage medium the data; Data positioning module basis Yuan data positioning data concrete depositing position; The Yuan data management module is responsible for a Yuan data the validity; The data buffer module provides the visit data the buffer mechanism. Enterprise through use intelligence network floppy disk, both may enhance the enterprise interior public data storage space, convenient data sharing and management, and may reduce to increase the storage space to increase the price which the server spends; On the other hand, the enterprise may reduce each personal computer’s storage space, enlarges the intelligent network floppy disk’s space or quantity, overall reduces the enterprise the price which spends for the memory.
Below detailed introduction intelligence network floppy disk’s data accessing module and system software part.
1 hardware design
The intelligent network floppy disk hardware design’s core is Samsung Corporation’s S3C44BOX microprocessor. The S3C44BOX microprocessor basic frequency is 66 MHz, uses the ARM7TDMI essence, supports 16 Thumb sets of instructions and 32 ARM sets of instructions; Supports 8 32 MB the memory bank address spaces. In order to reduce the cost, SaC44BOX has provided on the rich piece the equipment, including 8 KB Cache, SRAM, the LCD controller, 2 channel UART, 4 channel DMA, the system supervisor (selects patches or strips of land as worth saving for seed logical, FP/EDO/SDRAM controller), to bring the PWM function 5 channel timer, 1 internal timer, the I/O port, RTC, 8 channel 10 ADC, the 12C bus interface, the 12S bus interface, the synchronized SIO connection and the PLL frequency multiplier. Was the S3C44BOX microprocessor increased 2 MB F1ash, 8 MB SDRAM, 1 IDE connection and 1 RTL8019AS ethernet correspondence chip outside the piece. Flash mainly uses in depositing the BootLoader procedure, the uClinux essence reflection, the ROMFS filing system and the application procedure. The intelligent network floppy disk uses the IDE connection hard disk to take the storage medium. The ordinary IDE connection hard disk data transfer rate is 133 Mbps, is by far quicker than the magnetic tape unit, is advantageous to the data transmission; The solid state memory storing velocity is freely quick, but its expensive price caused it at still not to be suitable for the mass data memory at present. S3C44BOX development board’s functional block diagram as shown in Figure 1.
The S3C44BOX microprocessor provides 25 address bus Addr0~Addr24, provides 16 data bus data0~datal5, therefore the SaC44BOX support’s biggest storage medium space is 32 MB. Between the IDE hard disk and the memory carries on the data transfer according to the DMA way, but between the ether network card and the memory uses the interrupt mode to carry on the data transfer. Regarding the S3C44BOX microprocessor, the SDRAM arrangement in 6th either 7th bank, the address distinguishes OxOc000000 or the OxOc800000 start. ATA connection located at 2nd bank, but ethernet connection located at 1st bank.
2 software designs
Intelligent network floppy disk system software functional module as shown in Figure 2. The IND software accepts the request, to request the dispatcher, functions responsibly and so on data distribution management and data positioning; VFS is the virtual file system, provides the unification for the different logic file system the connection; ROMFS and Ext2 are the logic file systems. The block device driver provides a unified connection for the different block equipment, and is responsible for the block equipment data buffer function; The ATA connection driver provides the standard at bus interface driver; The TCP/IP agreement and 802.3 agreements compose an agreement stack, causes the equipment to be possible to use in the ethernet, the data may undergo the Internet transmission; The network equipment after the 8019AS chip connection, has provided the RTL8019AS chip driver for this reason.
The IND software module response user reads the request and writes the request, according to comes to serve the strategy dispatch first to request first, global administration data on floppy disk’s distributed view. When has the connection request, the IND software module must produce a lightweight advancement, the response connection requested, and according to request Yuan data, decision document memory and read set. The customer and between the IND intelligence network floppy disk uses the non-condition connection, reduces the complexity which between the customer and the network floppy disk connects. When opens a network disk file, the data deposits by a temporary file’s form on the local system, the later operation is carries on the operation to the local temporary file, after opening finished, on network floppy disk corresponding document object automatic shut-off, response advancement death. In close file time, if the document has been revised, then writes the network floppy disk, and deletes the local temporary file; If the document has not passed through revises ‘ does not need to carry on writes the operation, only in local deletes the temporary file then. In the ordinary circumstances, opens when the document must establish a connection, but time close file possibly must establish a connection, also possibly does not want. The table of contents is one kind of special document, carries on processing according to the general series.
At present, the system only supports two kind of filing system ROMFS and Ext2. ROMFS is a small ROM filing system, can only read cannot write. It contained has needed the application procedure which moved on uClinux, in the uClinux operating system translation period bedding bag contained in the uClinux binary code. Ext2 filing system installment in ROMFS in filing system’s /var table of contents. After systems operation, the ROMFS filing system and ext2 filing system’s in memory logical relation as shown in Figure 3. What belt “*” is the Ext2 filing system object, what does not bring “*” is the ROMFS filing system object.
The network service uses the TCP/IP agreement and 802.3 agreements realizes. The ethernet from a sharing, low speed topology has developed into one kind of high performance lucky bit exchange transmission technology, uses the ethernet technology to be advantageous to the network floppy disk to the lucky bit ether on-line transplant. The TCP/IP agreement is one kind of open style network interconnection agreement, compatible, the popular degree is high, the data may through the Intemet transmission.
3 intelligent network floppy disk system software’s realization
The intelligent network floppy disk uses uClinux to take the operating system. uClinux is for does not bring to inlay the person type Linux operating system which specially MMU CPU designs, has the following merit: First, its sound code under the GNU public permit is open, anybody may use freely and study; Second, uClinux uses the modular design, has strongly may the reduction, the user may according to own need to increase or the reduction functional module; Third, the uClinux function is formidable, supports multi-functions and so on duty operation, TCP/IP agreement stack, many kinds of filing systems; Fourth, uClinux probability, already successfully transplanted to each kind of CPU platform. Looks like S3C44BOX, Motorola MC68000, MCF5206 and MCF5207ColdFire and so on; Fifth, uClintlx also has 1 with it compatible small C language storehouse uClihc, it and GNUC language storehouse glibc are compatible, convenient user development application procedure. At present, uClinux supports 3 Linux essence edition, respectively is 2.O.x, 2.4.x and 2.6.x, what this design uses is the 2.4.xLinux essence. This essence and IEEE the POSIX standard is compatible, causes to open the source code not to pass through majority of revises, only needs to translate simply may transplant to the goal platform.
When realizes the intelligent network floppy disk, has developed first based on the S3C44BOX microprocessor’s system circuit wafer, then transplants the uClinux operating system to this circuit wafer on, finally compiles the IND software. Below mainly introduces the uClinux operating system’s transplant process and the uClinux operating system’s guidance process.
When transplants the uClinux operating system, must obtain a complete uClinux operating system sound code first, may also download a complete uClinux compact disc from the website, may also download the essential sound code from the website, like the Linux essence, the uClinux patch procedure, uClibc and need application procedure sound code. What we download is uClinuX_dist 120,041,216 .tar compact discs, contains to s3C44BOX the support. Next is must establish the cross compiling development environment. The part disposition content which produces in view of the circuit wafer is as follows:
#define CONFIG_ARCH_SAMSUNG 1
#deflne DRAM_BASE OxOc000000
#define DRAM_SIZE 0×00800000
#cleftne Flash_MEM_BASE Ox0000000
#define FIash_SIZE0×00200000
#deflne CONFIG_RAMKERNEL 1
#deflne C()NFIG_SPU_NAME ” S3C4480X “
#define CONFIG_CPU_S3C44BOX 1
#define CONFIG_CPU_ARM710 1
#define CONFIG_CPU_32v4 1
#defIne CONFIG_CPU_32 1
#defIne CONFIG_No_PGT_CACHE l
#define CoNFIG_CPU_WITH_CACHE 1
#define CONFIG_ARM_CLK(6000000)
#define CoNFIG_SERIAL_S3C4480X 1
May see from the above content, Flash located at S3C44BOX 0th Bank, the address from Ox00000000 to 0×00200000, the capacity is 2MB. SDRAM located at 6th Bank, the address from Oxoc000000 to 0xOc800000, the capacity is 8 MB. The S3C44BOX operating frequency is 60 MHz, the serial port uses on S3C44BOx piece UART, and supports the control bench function on this serial port, causes uClinux the start produce information to be possible to demonstrate in the super terminal. Other dispositions including the TCP/IP network, 10/100 Mbps ether network, IDE and contents and so on ext2 filing system. Disposes the uClinux operating system has the process dispatching module, the memory management module, the ATA connection driver, the filing system, TCP/1P functions and so on agreement stack, network card actuation.
the uClinux disposition will complete later then to the uClinux translation, will produce two documents: Right and wrong compression’s uClinux operating system binary code uCllnux_bootram.bin, it the start address which works in SDRAM is 0xoc008000; Another is compression uclinux operating system binary code uClinux_bootrom.bin, writes about in Flash through the JTAG line cable fever, loads from the bootloader procedure it to SDRAM in carries out. Must carry on the solution compression first in system initiation’s time uCIinux_bootrom.bin, deposits to SDRAM, then skips to the uClinux operating system’s entrance execution. Essence when start must inspect machine’s CPU type and the architecture, initialization CPU, establishes the RAM page table and the interrupt arrow meter, the loading equipment driver. After all these complete, uClinux founds the initial init advancement, installment root filing system ROMFS and the ext2 disk file system. Finally, the operating system will carry out the IND software automatically, the waiting receive client side request.
the uClinux operating system’s guidance completes through the B00tlDader procedure. From says essentially, it does not belong to the operating system essence, in view of the different CPU architecture, does not have the probability. This design compiles Bootloader procedure when system initiation completes the following several work:
①Will deposit the operating system essence which compresses in Flash carries on the solution compression, then duplicates in SDRAM which starts from 0xoc008000 place;
②The rewriting system’s memory address mirror image, the RAM start address mapping is O;
③Establishes CPU the sp register, and essence BSS section reset;
④Establishes CPU the pc register, causes its value direction essence the start address.
4 performance analyses
The intelligent network floppy disk’s performance receives system each aspect the restriction, looks like the IND software’s process dispatching strategy, local area network’s band width, the ATA main line’s band width, filing system’s buffer mechanism and the client side buffer mechanism. Here analyzes filing system’s buffer mechanism and the system data turnover rate, makes a preliminary weight by this to the intelligent network floppy disk’s performance.
The virtual file system and the block device driver uses the high speed buffer technology generally, most often will use recently the data storage in the memory, enhances the data in the memory hit probability. Filing system’s table of contents item of object, the index node object, the document object and the vfsmount object have in the independent high speed buffer area, when requested object in high speed buffer area, and is effective time, directly takes out the data transmission from the high speed buffer area for the customer; If requested the data does not exist, takes out an idle object in the high speed buffer area to take the new object the descrptor, like this may reduce to found the new object to assign the time which the memory spends, raises system’s efficiency. Regarding index node object, table of contents item of object and vfsmount object, to raise their search efficiency, these objects exist in they respective Hash table. Regarding the block device driver use high speed buffer area, may reduce reads storage device’s number of times frequently. Must use certain prefetching mechanism to the client side directory file’s read, because opens to the directory file is quite frequent, opens a table of contents every time, must establish a connection, therefore, picks the feasible prefetching mechanism to be possible to reduce the establishment connection effectively the number of times.
The system performance test uses the BenchMark software. The hardware test platform by the intelligent network floppy disk, the l00MB switchboard and 24 clients is composed. The test document size is 1 MB, the client reads the request stochastically to the intelligent network floppy disk transmission, test result as shown in Figure 4. When turnover rate expression multiuser request in unit interval/unit time through network transmission data total quantity.
May obtain from the test result, when the customer number increases gradually, each customer obtains average band width by gradually few. When the customer increases to 24, each customer may obtain approximately the O.3 Mbps band width, may satisfy the document long-distance access request.
Conclusion
This article first introduced the intelligent network floppy disk’s hardware development environment, then introduced in detail the intelligent network floppy disk’s software module and the key technologies, have realized the intelligent network floppy disk finally on the S3C4480X embedded development board. Client side when visit intelligence network floppy disk, the speed also waits for further enhancing. This may from the improvement network environment, raise network card’s speed to begin, requests the scheduling strategy to the client side also to be possible to take an aspect the research, other functional module also needs to continue to increase. Believed that the intelligent network floppy disk to the enterprise is a good solution storage device question plan.
