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Electing Data Storage Allocation Sizes

IP.com Disclosure Number: IPCOM000042870D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 3 page(s) / 45K

Publishing Venue

IBM

Related People

Green, JG: AUTHOR

Abstract

By selecting a suitably-sized allocation unit, fragmentation of data in a storage volume can be reduced. The storage volume is divided into allocation units referred to as "buckets". Each data unit, or data set, to be stored within a data storage volume carries a record of growth. The allocation device analyzes the growth parameters, together with the size of the data unit, or data set, and selects an allocation size, set forth in buckets for each data set. In this manner, the allocation size is tailored to the growth characteristics of the data unit to be stored. High-growth data units receive relatively larger allocations, while the zero, or slow, growth data sets receive correspondingly smaller allocations with respect to the original size of the data set.

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Electing Data Storage Allocation Sizes

By selecting a suitably-sized allocation unit, fragmentation of data in a storage volume can be reduced. The storage volume is divided into allocation units referred to as "buckets". Each data unit, or data set, to be stored within a data storage volume carries a record of growth. The allocation device analyzes the growth parameters, together with the size of the data unit, or data set, and selects an allocation size, set forth in buckets for each data set. In this manner, the allocation size is tailored to the growth characteristics of the data unit to be stored. High-growth data units receive relatively larger allocations, while the zero, or slow, growth data sets receive correspondingly smaller allocations with respect to the original size of the data set. A data unit, or data set, includes a size indicating parameter portions. Additionally, growth parameters are stored with the data unit. Pointers to previously determined and stored growth parameters (labels) can be included. A time stamp in the growth parameter identifies opening and closing processing exclusive of read-only processing. The number of allocation buckets filled during that processing time is also included. The total active time of the data set, and the time stamp of the earliest open of a rolling average of in terms are referred to later as "TE". As soon as the processing programmable computer determines that another allocation bucket is filled during the data unit processing, the current time is saved. This is called "TC". A rolling average of active time of the data set is computed using the previously "N" (N as in integer) written labels, hereinafter referred to as "TN". The total number of new allocation buckets required across the N-previous processing units, identified in the N-previous labels, is determined. This sum is termed "BN". Then the ratio BN/TN indicates the number of allocation buckets allocated for unit times over the N-most recent time period. This ratio is a prime growth parameter used for determining allocation size. Then the time stamp of the first, or oldest, record in the allocation bucket is obtained. This time stamp is termed "T zero", then TC minus T zero is calculated. The difference represents the elapsed time for an allocation bucket to overflow, which is indicated as "TB". Overflow time is preferred since the time required to fill the bucket may have happened a long time before the bucket actually overflows. The above represents the historical growth parameter data usable by the allocation selector to select the desired allocation increase for next storing the data sets. For example, if a negative growth is determined, then the same, or less, allocation size as previously used can be employed. For zero growth, the same, or somewhat larger, allocation can be employed. For a first growth rate, rate 1, a predetermined larger allocation is employed. Otherwise, for a high rate growth, rate 2, an a...