Magstar 3570 AS/400 to LTO Unix Data Conversion

Restoring data from tapes when you no longer have the drive to read them can be problematic. Add to this a change of operating platform from AS/400 to UNIX and the need to therefore restore AS/400 objects on a UNIX system in a usable form, and the problems increase dramatically. This was the case for one customer and it was beginning to look as if they would need to re-instate their original system to have any chance of accessing the data, then they contacted Altirium. Scenario Magstar 3570 data cartridges were popular on IBM systems during the 1990s as high performance near-line storage. As the decade ended and LTO Ultrium became the dominant force in tape storage there was a move away from 3570 and similar backup tape. One Altirium customer having survived the pain of migrating all of their tape hardware over to LTO Ultrium, and having retired the last of their Magstar drives were more than a bit surprised to discover that there were still 100 3570 tapes sitting in the archive and with a retention requirement of 30 years. The Case The tapes contained SAVOBJ backups of data from the company's AS/400 systems, IBM standard labelled tapes, with large volumes of financial and other business historical data. A further complexity was a requirement to transfer much of the financial information across to another office where the systems had been migrated from AS/400 to UNIX and so a major conversion of the data was required. This meant that not only did the data from the 3570 cartridges have to be read from the tapes and written out to LTO cartridges, but the data contents required modification. The AS/400 uses the EBCDIC data set to represent printable data, UNIX systems are ASCII based. Further, the methods of storing numeric values under COBOL from the AS/400 do not readily translate to applications on other platforms. The COBOL data comprises a large number of COMP3 and Zoned Decimal fields which, if not translated into printable ASCII would lose all meaning during any data migration process. For these types of files under the AS/400 OS there is embedded record description information and we were able to use this information to decode the data. Having read the data from all of the tapes on to a two of our systems, a decoding process was run to produce files that could be loaded into any mainstream UNIX or Windows application without any data loss or disparities from the original data. The 100 3570 data cartridges ended up on just two LTO Ultrium 3 data cartridges, a further copy of the original data was written out to another set of LTOs for any future requirement the customer may have to read the data back onto the AS/400, but in one fell swoop the data had been transferred to up-to-date tapes and migrated on the way past. Not all AS/400 data conversion can be dealt with in this manner, but even without record description information from within the data it is usually practicable to work out the structure and organisation of it and to perform similar translation work to that described here.

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