Electrical computers and digital data processing systems: input/ – Input/output data processing – Data transfer specifying
Reexamination Certificate
1998-10-29
2002-02-19
Lee, Thomas (Department: 2182)
Electrical computers and digital data processing systems: input/
Input/output data processing
Data transfer specifying
C710S006000, C710S120000, C709S231000, C348S086000
Reexamination Certificate
active
06349349
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for storing data including audio and/or video (AV) data and for transmitting them, suitable for being applied to an AV server device for storing and reproducing AV data etc. More specifically, the invention relates to an apparatus making it possible to construct a data processing system in which real time control can easily be carried out and excellent responsivity can be exhibited, by connecting an receiving buffer unit for storing temporarily AV data etc., an transmitting buffer unit for transmitting AV data etc. and the like unit by means of a network means.
2. Description of the Prior Art
A structure shown in
FIG. 22
is known as an AV server device which is a type of an apparatus for storing AV data etc., and for transmitting the desired AV data at real time.
In the
FIG. 22
, a HDD (Hard Disk Drive) array unit
12
(which will be referred to as a disk array unit, hereinafter) having such an array structure that a plurality of hard disk drives are connected in parallel with each other is provided for using as a storage means for storing AV data, and this disk array unit
12
is connected to an internal bus
16
through an SCSI interface
14
.
To the internal bus
16
, a receiving interface
20
for AV data supplied from a terminal
18
is connected so that the received AV data are stored in the disk array unit
12
, and thereto an transmitting interface
22
is connected through the internal bus
16
so that the reproduced AV data are transmitted from a transmitting terminal
24
.
A control signal interface
28
for a real time control through a terminal
26
is also connected to the internal bus
16
.
As the control signal, the following can be taken into consideration: a signal transmitted from an editing unit (not shown) connected to an AV server device
10
, a signal synchronized with sending-out-timing signal transmitted from a program sending-out unit (not shown) disposed in connection with an application terminal
36
in case where this AV server device
10
is illustratively applied to a commercial sending-out system.
Furthermore, the followings are connected to this internal bus
16
: a CPU
30
for controlling the whole of the AV server device, a ROM
32
including various control programs, and a RAM
34
for storing, for example, file control information for AV data stored in the disk array unit
12
. In addition to this, in this example, to the internal bus
16
a network interface
40
is connected, and the present AV server device is connected to the outer application terminal
36
(terminal equipment such as a workstation or a personal computer) from this network interface
40
through a network
38
.
Reproducing operations for AV data stored in the AV server device are illustratively explained hereinafter.
Firstly, the application terminal
36
sends a file information acquiring command to the AV server device
10
through the network
38
. Said file information acquiring command orders the indication of the information relating to the file storing the AV data to be reproduced. Next, CPU
30
of the AV server device
10
transfers the file information stored in RAM
34
therefrom to the application terminal
36
in response to the file information acquiring command received from the application terminal
36
.
Then, the application terminal
36
sends to the AV server device
10
a file open command that is a command to operate the file storing AV data to be reproduced on basis of the received file information. The CPU
30
of the AV server device
10
reads out the file information stored in the RAM
34
on the basis of the received file open command and waits for a next command from the application terminal
36
. Next, the application terminal
36
issues to the AV server device
10
a reproducing command relating to the file received the file open command. The CPU
30
of the AV server device
10
receives said reproducing command and issues a reproducing command relating to the file to be reproduced to the disk array unit
12
through SCSI interface
14
according to the read out file information. The disk array unit
12
receives said reproducing command and allows the hard disk drive inside the unit
12
to be accessed. Thereby, the AV data are reproduced from the area where said file to be reproduced is stored in hard disk of the hard disk drives and the reproduced AV data are transferred to the internal bus
16
through the SCSI interface
14
. The CPU
30
controls the internal bus
16
so that the AV data transferred into the internal bus
16
are transmitted to the transmitting interface
22
. Said CPU
30
, thus, transmits the AV data to the outside via the transmitting interface
22
.
In the above AV server device
10
, all of the receiving interface
20
, the SCSI interface
14
and the transmitting interface
22
are connected to the internal bus
16
, and the CPU
30
controls all of them. All of the AV data are stored in the disk array device
12
. Thus, there remain the following problems.
Firstly, the number of the receiving and transmitting channels is limited by a transfer rate at the internal bus. This is because the receiving interface
20
and the transmitting interface
22
are directly connected to the internal bus
16
and consequently the number of the receiving and transmitting channels is limited by a restriction to hardware (a transfer rate at the internal bus).
For example, when the transfer rate at the internal bus
16
is 20 Mbyte/sec (=160 Mbps), the total number of the receiving and transmitting channels is 8 at maximum in case where the compression rate for AV data is 20 Mbps.
Secondly, since the receiving interface
20
and the transmitting interface
22
are directly connected to the internal bus
16
, it is impossible to arrange receiving means, transmitting means, storage means, and the like in a physically separate form. Thus, a design for construction of an AV server system is restricted.
Thirdly, the reliability of the disk array unit
12
deteriorates since the disk array unit
12
is controlled at real time in recording/reproducing AV data. For example, it will be assumed that in case where a plurality of the transmitting interfaces
22
exist, these plural transmitting interfaces are simultaneously operated.
In order that transmitting AV data from the respective transmitting interfaces are not interrupted, it is necessary that a specified amount of data reach each of the transmitting interfaces within a specified period. This requires real time reading about reading data in the hard disk.
In hard disks, seek time and rotation-waiting time vary depending on the position of a head. Therefore, in order to reproduce AV data without interruption, it is necessary that seek time and rotation waiting time are set to the worst value. To obtain a transfer rate necessary for this, it is necessary to provide many hard disks and operate these disks in parallel.
The reliability of a hard disk is obtained on the basis of retry processing of the access to the hard disk. Therefore, when the retry number for a hard disk is limited to a minimum number (10 or less in usual cases), the error rate is deteriorated from 100 to 1000 times. Where hard disks are arrayed and real time reading is required, the retry number for the hard disks has no choice but to be limited. As a result, the reliability as a disk array unit drops.
Fourthly, to increase storage capacity, only addition of the disk array units
12
is permissible. When a tape device (a tape changer device using many magnetic tapes, or the like), which is low-priced for capacity, attempts to be used because of a high price of a hard disk drive, this tape changer must also be connected to the internal bus
16
. As a result, transfer capacity of the internal bus
16
is further consumed, so that the number of receiving and transmitting channels, which can be handled, is reduced for that.
Fifthly, the period from the arrival of a file open command from the application termi
Fujita Hiroyuki
Ito Norikazu
Katsuo Satoshi
Mizutani Shintaro
Okayasu Gentaro
Elamin Abdelmoniem
Frommer William S.
Frommer & Lawrence & Haug LLP
Lee Thomas
Simon Darren M.
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