Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
1997-03-25
2001-06-05
Yoo, Do Hyun (Department: 2185)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S114000, C710S008000
Reexamination Certificate
active
06243790
ABSTRACT:
This invention relates to disk arrays, and more particularly to disk arrays in which disk drives having different logical parameters can be easily transposed or rearranged in the array for testing purposes and the like.
BACKGROUND OF THE INVENTION
Modern disk arrays simultaneously operate a plurality of disk drives which are processed as a single disk unit through parallel combinations of units. This increases both performance and reliability are increased.
As a practical way to improve reliability, it has been recognized to provide an exclusive parity or hamming code disk within the disk array apparatus. Moreover, it is also known to provide a hot spare disk, so that even if a single disk develops a fault, processing can be done continuously without suspending the operation of the system.
In general, a plurality of magnetic disks are arranged in parallel within the disk array apparatus. Combinations of physical magnetic disks are grouped to form one or more logical disks. As to the combination method, several types have already been proposed. The respective types are called RAID (Redundant Array Of Inexpensive Disks) levels. For each RAID level, the control method of the disks combined as a logical disk is controlled by a different operation method.
The RAID levels are called RAID level 0 to RAID level 5. The concept of each RAID level and operating method are described in The RAID Book (The RAID Advisory Board, Inc. issued on Nov. 18, 1993).
Moreover, a disk array apparatus which allows coexistence of a plurality of types of logical disks within one drive module group has been developed. As seen in
FIG. 1
, a total of 24 disks, including six disks in the lateral direction and four disks in the vertical direction, are arranged in the matrix structure within one unit of the disk array apparatus.
In
FIG. 1
, the lateral arrangement of a drive module group
102
is called a rank. In general, one logical disk has a plurality of physical disks in the same rank.
The vertical arrangement is called a port. From the hardware point of view, data transfer may be realized independently for each port.
In
FIG. 7A
, an example of a logical disk assigning method is indicated. A device of rank(x)/port(y) is described as DVxy. The 24 devices are respectively assigned in such a manner that DV
00
-DV
04
are defined as logical disk
0
, while DV
10
-DV
14
are logical disk
1
, DV
20
-DV
24
are logical disk
2
and DV
30
-DV
34
are logical disk
3
. HS-
0
, HS-
1
, HS-
2
and HS-
3
are assigned respectively as the hot spare disks. The hot spare disks are used to newly store data which was stored in a relevant physical disk when a fault is generated in the disk, disabling read and write operations of data in that disk. The data to be stored in the hot spare disks are reproduced from the contents of the other disks constituting a logical disk to which the relevant physical disks belong.
FIG. 7B
shows the RAID level assigned to each logical disk in the structure explained above. In
FIG. 7B
, logical disks
0
-
3
are all set to RAID level 3 or RAID level 5.
FIG. 8A
shows another example. In
FIG. 8A
,
24
devices are respectively assigned in such a manner that DV
00
-
04
are defined as logical disk
0
, DV
10
-DV
11
as logical disk
1
, DV
12
-DV
13
as logical disk
2
, DV
14
as logical disk
3
, DV
20
-DV
22
as logical disk
4
, DV
23
-DV
24
as logical disk
5
, DV
30
-
31
as logical disk
6
, and DV
32
-DV
34
as logical disk
7
. HS-
0
, HS-
1
, HS-
2
and HS-
3
are assigned respectively as hot spare disks. The function of the hot spare disks is similar to those of FIG.
7
.
FIG. 8B
shows the RAID level assigned to each logical disk in the structure described above. In
FIG. 8B
, the logical disk
0
is set to the RAID level 3 or 5, logical disks
1
and
2
to the RAID level 1, logical disk
3
and
4
to the RAID level 0, logical disks
5
and
6
to RAID level 1 and logical disk
7
to RAID level 0.
In the disk array apparatus of the structure explained above, particularly in the apparatus as shown in
FIG. 8
, a variety of logical disks of various RAID levels coexist. When such a structure is employed, a disk array controller cannot control the logical disks if the disk array apparatus does not accurately detect the layout of the logical disks. For example, in
FIG. 8
, DV
10
to DV
14
cannot be operated under the assumption that they are set to RAID level 3.
In order to prevent such an erroneous assumption, the position in the relevant drive module group for insertion of the relevant physical disk (referred to as “physical address”) is recorded in each physical disk in the apparatus. Such information is generally known as AIR (Array Integrity Record) information. This AIR information is written in the factory before delivery.
The disk array apparatus inspects the physical address with reference to the AIR information recorded in the physical disk loaded therein. If mismatching between the actual inserting position and the physical address of the AIR information is detected, the relevant logical disk is disabled.
As explained above, erroneous recognition of logical disks resulting from erroneous insertion of a physical disk into an incorrect slot can be prevented. However, disk array apparatus developed in recent years is capable of providing a plurality of logical disks within one drive module group. In the disk array apparatus of the related art, an individual disk apparatus can be controlled on the basis of its physical position. Therefore, control of the logical disk also naturally depends on the physical position of the disks being correct. Accordingly, transposition or rearrangement of the logical disk within the apparatus has not been possible.
NEEDS, OBJECTS AND SUMMARY OF THE INVENTION
There is a need for a disk array apparatus in which disks can easily be transposed or re-arranged regardless of the logical disk of which they are a part for many reasons. First, it would allow a user to determine, when a fault is generated, if the fault lies in the disk apparatus itself or in its connection. Second, easy transposition of disks would allow a user to re-arrange the data structure without copying the logical disk, saving a great deal of time and money. Third, in the case of extending the logical disks by adding new logical disks or the like, such an apparatus would not restrict the physical address into which the disk must be inserted, allowing disks of any size to be inserted. As a result, production and stock of additional disks could be simplified, and productivity increased.
Accordingly, an object of this invention is to provide a new and improved disk array apparatus which easily enables transposition or re-arrangement of disks.
Another object is to provide a reliable and easily maintained disk array apparatus which allows for the addition of a variety of logical disks within a single apparatus and easy transposition of disks within the group of disks, even when the logical disks have different data formats and protocols. In fact, an object is to provide for accurate recognition of the logical designations for disks, at the time of their transposition, even if the relative position of a disk apparatus within the logical disk arrangement is changed.
In keeping with one aspect of the invention, a disk array includes a drive module group composed of a plurality of disk apparatus for storing data to be transferred to or from a host apparatus, and at least one disk apparatus for storing redundant data generated from the data stored in the data storing disk apparatus to be transferred to or from the host apparatus. Array controllers accept instructions issued by the host apparatus to analyze their content, operating the disk apparatus depending on the instruction issued by the host apparatus, or requesting data transfer and controlling data transfer between the host apparatus and disk apparatus. Structure information including position in the drive module of the disk to be accessed is recorded in the disk apparatus.
The drive module group includes a plurality of disk
Encarnacion Yamir
Fujitsu Limited
Greer Burns & Crain Ltd.
Yoo Do Hyun
LandOfFree
Methods and apparatus for re-arranging logical drives in a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods and apparatus for re-arranging logical drives in a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods and apparatus for re-arranging logical drives in a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2467146