Apparatus and method for placing data on a partitioned direct access storage device

• US 4,607,346 A
• Filed: 03/28/1983
• Issued: 08/19/1986
• Est. Priority Date: 03/28/1983
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hill, Reed A.
• Primary Examiner(s): Heckler, Thomas M.
• Application Number:
  US06/479,384
• Time in Patent Office: 1,240 Days
• Field of Search: 364/200 MS File, 364/900 MS File
• US Class Current: 711/170
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems

Abstract

A storage device, such as a direct access storage device, is partitioned into a plurality of partitioned devices having different access and storage characteristics matched to the required perforamnce. Data may be stored on that partitioned device which most nearly meets the storage characteristics of the data, where the access and storage characteristics of data are related to its volume and frequency of access.

Claims

1. A method for operating a computing apparatus to automatically allocate data sets among storage devices in such a manner that system degradation will be minimized by reducing device bottlenecks and the cost of storage will be minimized by the effective ultization of storage device space and access capability, comprising the steps of:

calculating the access density of a data set to be allocated as equal to the number of accesses per unit time to that data set divided by the data set volume;

calculating the access density of each of a plurality of storage devices attached to the system as equal to the number of accesses that a device can sustain per unit time divided by the data storage capacity of the device;

allocating the data set to a storage device that has sufficient available space and a device access density most nearly matching and exceeding the access density of the data set being allocated; and

continuously monitoring and recalculating the data set access density and reallocating the data set as required to maintain the data set on a device having the most nearly matching access density.

2. The method of claim 1, comprising the further sign responsive to a request for access to a particular logical device address of computing the physical device address to account for the partitioning of the device into high and low access density partitions.

3. A method for operating a computing apparatus to partition a single direct access storage device into a plurality of logical devices having different device characteristics matching the device performance required for a plurality of data sets, comprising the steps of:

selecting data sets to be stored on the physical device, and calculating for each data set its access density as a function of the rate of inquiries to the data set and the data set volume;

selecting data sets having access densities equal to or greater than the basic device access density for assignment to a partition designated to support a high access density, said device access density being calculated as a function of the rate of access which the device can sustain and its storage capacity;

setting the access density of the high access partition equal to the highest access density of the data sets assigned to the high access partition;

selecting data sets having access densities less than the basic device access density for assignment to a low partition designated to support low access density;

setting the access density of the low access partition equal to the highest access density of the data sets assigned to the low access partition; and

partitioning the total capacity of the device between high and low access partitions such that the high access partition contains sufficient volume to yield the required access density.

4. A method for operating a computing apparatus to partition a storage device into a plurality of logical devices, comprising the steps:

calculating the access density of the device as equal to the total accesses per unit time sustainable by the device divided by the total storage capacity of the device;

determining for each of a plurality of data sets to be stored on said storage device a data set access density equal to the total accesses per unit time to be made to that data set divided by the volume of data allocated to a data set;

allocating the data sets to at least two groups based upon their access densities, and assigning to each group an access density value related to the access densities of the assigned data sets;

partitioning the device into a plurality of logical devices of different access densities, where the sum of the access densities of the logical devices equals the access density of the storage device; and

assigning each of said groups to a logical device on the basis of their respective access densities.

5. A method for operating a stored program digital computer to store and access data records from a plurality of data sets on a direct access storage device of the type having a plurality of concentric data storage cylinders, where a cylinder comprises a one or more tracks, comprising the steps of:

partitioning the storage device into a plurality of partitioned devices including a first partitioned device having at least first and second cylindrical parts and a second partitioned device including a third cylindrical part concentric with and contained within said first and second cylindrical parts;

determining the access densities of a plurality of data sets each as a function of the rate of inquiries to the data set and the data set volume; and

storing in said first partitioned device data records in one or more data sets having one predetermined range of access densities and in said second partitioned device data records in one or more data sets having a different predetermined range of access densities greater than that of said one range.

6. A method for operating a stored program digital computing apparatus to store and access data records from a plurality of data sets on a plurality of at least two storage devices, comprising the steps of:

determining the access densities of at least a first and a second storage device each as a function of the rate of accesses which the respective device can sustain and its storage capacity, the access density of the first storage device being greater than the access density of the second storage device;

determining the access densities of a plurality of data sets each as a function of the rate of inquiries to the data set and the data set volume; and

storing in said first storage device data records in one or more data sets having one predetermined range of access densities and in said second storage device data records in one or more data sets having a different predetermined range of access densities lower than that of said one range.

7. The method of claim 6, further comprising the steps of

monitoring the actual access density of data sets stored in said first storage device;

and

responsive to the actual access density of a given data set becoming substantially less than the access density of said first storage device, moving said given data set to another storage device.

8. Apparatus for storing and accessing data records in a plurality of data sets, comprising:

direct access storage device means having a plurality of concentric data storage cylinders, each cylinder comprises one or more tracks, for storing data signals;

said storage device means further comprising first partitioned device means having at least first and second cylindrical parts and second partitioned device means including a third cylindrical part concentric with and contained within said first and second cylindrical parts;

means for determining the access densities of a plurality of data sets each as a function of the rate of inquiries to the data set and the data set volume; and

means for storing in said first partitioned device means data records in one or more data sets having one predetermined range of access densities and in said second partitioned device means data records in one or more data sets having a different range of access densities higher than that of said one range.

9. The apparatus of claim 8, further comprising:

means for determining the device access density of said second partitioned device means as a function of the rate of accesses which the device can sustain and its storage capacity;

monitoring means for monitoring the actual access density of a data set as a function of time; and

means responsive to said monitoring means for removing from said second partitioned device means a data set having an actual access density which is substantially lower than the device access density.

10. The apparatus of claim 9, further comprising:

means responsive to said monitoring means for moving from said first partitioned device means a data set having an actual access density which is substantially higher than the access density of the first partitioned device means.

11. The apparatus of claim 8, further comprising:

means for storing as a stored access density a determined access density of a given data set assigned to said second partitioned device means;

means for monitoring the actual access density of said given data set as a function of time;

means, responsive to said actual access density of said given data set becoming substantially different from said determined access density, for substituting the actual access density for said determined access density as the stored access density in said means for storing;

means for determining when space is required on said second partitioned device means; and

means responsive to the stored access density for said given data set for moving said given data set to a partitioned device having an access density more nearly equal to said stored access density.