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Random File Access on Tape: RAO Accelerates Data retrieval

By Shawn Brume posted Thu January 05, 2023 03:07 PM

  

Organizations that need long-term retention of large amounts of data often rely on tape storage due to its endurance, low energy consumption, low total cost of ownership, and impressive sustainability. But when it comes to retrieving random files, it’s widely recognized that tape can’t match the speed of hard disk drives or flash storage.

But there’s some good news on that front. An innovation in tape technology called Recommended Access Ordering (RAO) has recently improved random file retrieval times for LTO 9 drives significantly. RAO has been available in IBM enterprise tape products for years, but only recently has this capability been added to LTO 9 full-high tape drives. 

RAO enables tape control applications to accelerate the retrieval of data segments or user data segments (UDSs) – files or blocks of data. It improves random access time to data segments on tape by as much as 86%, when compared with retrievals of the same data segments linearly.

    Table 1.  Summary of RAO segment retrieval performance at a glance by drive type

Let's take a detailed review of the IBM LTO 9 tape drive performance for retrieving random files.

LTO-9 performance specifications:

Native data rate of up to 400 MB/s
Native data physical capacity of 18000GB
The data compression keeps the ratio to 2.5:1
Support for 8Gb FC and 12Gb SAS connectivity
SkipSync Function to provide small file backhitchless flush capability
Cache buffer: 1024MB


LTO 9 L9 media RAO Performance

The Locate and Locate+Read performance of the IBM LTO 9 tape media on the IBM LTO 9 tape drive is described by the following set of charts that show how the drive behaves when locating or locating+reading data in the access order determined by RAO and Sorted by record number using differing numbers of 200MiB UDSes (4, 8, 16, 32, 128, 512 and 2000).


LTO 9 L9 media RAO Locate+Read Performance Range

The range of the Locate+Read performance of the IBM LTO 9 tape media on the IBM LTO 9 tape drive is described by the following set of charts that show how the drive behaves when locating+reading data in the access order determined by RAO and Sorted by record number using differing numbers of 200MiB UDSes (4, 8, 16, 32, 128, 512 and 2000).


During the performance testing the same magnitude of performance enhancement using RAO was observed when using LTO 8 (L8) tape media to read segments on LTO 9 tape drives.

Conclusions

Since the introduction of the first LTO tape drive, every successive generation has incorporated new features and performance improvements. Now the IBM LTO 9 tape drives in conjunction with the new LTO Gen 9 media represent an efficient solution for today’s growing storage demands.

 

IBM LTO 9 tape drives are already a smart storage solution for businesses requiring backup and archival storage of their data. With the addition of RAO, customers now have the same benefits, along with increased speed.

 

To learn more, check out the LTO 9 specs here: https://www.ibm.com/products/lto-9-tape-drive

 

____________________________

Performance Benchmark Protocols

 

All performance benchmarks were run on the following systems:

 

  • IBM System x3550 M5 server running RHEL 7.5 with QLogic ISP8324-based 16Gb Fibre Channel and N2225 12Gb SAS External HBA.
  • Performance data was captured with C-based performance measurement tools designed to fully exercise the host interface and tape drive with the least amount of overhead.
  • All data rates/capacity reflect a decimal basis where MB = 1,000,000 bytes and GB=1,000 MB.
  • Actual tape drive data rate and cartridge capacity will vary depending on data compression rates, server performance, operating system variability, firmware, and other factors.
  • All RAO tests were performed with tapes fully written with non-compressible data.
  • Multiple RAO runs were performed using random UDS locations for each number of UDSes of the size indicated to show an average time. Some charts show the minimum and maximum times of these runs to illustrate potential variations in results.

Extracted from original publication by 

Tsuyoshi Miyamura (miyamuu@jp.ibm.com)
Osamu Matsumiya (MOSAMU@jp.ibm.com)
Tape systems development
Tokyo, Japan


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