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A method to reduce seek time of tape storage layer in HSM by using short and long media

IP.com Disclosure Number: IPCOM000248096D
Publication Date: 2016-Oct-26
Document File: 3 page(s) / 39K

Publishing Venue

The IP.com Prior Art Database

Abstract

This invention utilizes 2 types of physical tape media at Hierarchical Storage Management (HSM) which has physical tape tier. One type is low capacity (in other words, short length) physical tape medium and another type is high capacity (in other words, long length) physical tape medium. At such HSM, there is a use case that copy of a data is allocated to more than two different physical tapes for redundancy. In such use case, this invention allocates at least one copy of a data to low capacity physical tape and prefers to read the data from low capacity physical tape if reading the data from physical tape is required. It can reduce the seek time of reading data from physical tape.

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A method to reduce seek time of tape storage layer in HSM by using short and long media

(Background)

Virtual tape storage like IBM TS7700 and Oracle VTL and Disk storage who has file system like IBM Spectrum Scale support Hierarchical Storage Management (HSM). HSM is a function which manages different types of storage media to utilize capacity of them efficiently by allocating the data accessed at a high frequency to high speed and expensive storage medium and allocating the data accessed at a low frequency to low speed and cheep storage medium. For example, IBM TS7700 is designed to allocate the data accessed at high frequency to hard disk drive (HDD) and the data accessed at low frequency to physical tape.

Nowadays, capacity of tape media has increased so seeking a data in a physical tape has taken longer time in association with the increase of capacity of physical tape media. For example, tape length of IBM 3592 JD medium is 1072(m) [non-patent literature 1] and its maximum speed of seek by IBM TS1150 tape drive is 18(m/s). Therefore, assuming the move from beginning of a physical tape to center of it is averagely required at seeking a data in JD medium by IBM TS1150 tape drive, it takes about 30(s) (= 1072/2/18).

This invention is for solving the problem that seek time of a data in physical tape takes a long time at HSM.

(Descriptions)

This invention utilizes 2 types of physical tape media at Hierarchical Storage Management (HSM) which has physical tape tier. One type is low capacity (in other words, short length) physical tape medium and another type is high capacity (in other words, long length) physical tape medium. At such HSM, there is a use case that copy of a data is allocated to more than two different physical tapes for redundancy. In such use case, this invention allocates at least one copy of a data to low capacity physical tape and prefers to read the data from low capacity physical tape if reading the data from physical tape is required. For example, the length of JL medium which is writable with the same recording format available at JD medium is 281(m) [non-patent literature 1] and its maximum speed of seek by TS1150 tape drive is 18(m/s). Therefore, assuming the move from beginning of a physical tape to center of it is averagely required at seeking a data in JL medium by IBM1150 tape drive, it takes about 7.8(s) (= 281/2/18). As written before, in the same condition, seeking a data in JD medium by TS1150 tape drive takes about 30(s) so utilizing JL media can reduce the seek time by 74(%) (= (30-7.8)/30) comparison to utilizing JD medium.

Figure 1 shows a flow of writing data process in the case this invention is applied. This case assumes that copy of a data is allocated to at least two different locations at HSM which has HDD tier (upper layer) and physical tape tier (lower layer).


(1) Both low capacity (in other words, short length, for example, IBM 3592 JL medium) physical tape medium and high capacity (in...