[Full disclosure: I helped develop the underlying hardware for VSM 1-3 and also way back, worked on HSC for StorageTek libraries.]
Virtual Storage Manager System 6 (VSM6) is here. Not exactly sure when VSM5 or VSM5E were released but it seems like an awful long time in Internet years. The new VSM6 migrates the platform to Solaris software and hardware while expanding capacity and improving performance.
What’s VSM?
Oracle StorageTek VSM is a virtual tape system for mainframe, System z environments. It provides a multi-tiered storage system which includes both physical disk and (optional) tape storage for long term big data requirements for z OS applications.
VSM6 emulates up to 256 virtual IBM tape transports but actually moves data to and from VSM Virtual Tape Storage Subsystem (VTSS) disk storage and backend real tape transports housed in automated tape libraries. As VSM data ages, it can be migrated out to physical tape such as a StorageTek SL8500 Modular [Tape] Library system that is attached behind the VSM6 VTSS or system controller.
VSM6 offers a number of replication solutions for DR to keep data in multiple sites in synch and to copy data to offsite locations. In addition, real tape channel extension can be used to extend the VSM storage to span onsite and offsite repositories.
One can cluster together up to 256 VSM VTSSs into a tapeplex which is then managed under one pane of glass as a single large data repository using HSC software.
What’s new with VSM6?
The new VSM6 hardware increases volatile cache to 128GB from 32GB (in VSM5). Non-volatile cache goes up as well, now supporting up to ~440MB, up from 256MB in the previous version. Power, cooling and weight all seem to have also gone up (the wrong direction??) vis a vis VSM5.
The new VSM6 removes the ESCON option of previous generations and moves to 8 FICON and 8 GbE Virtual Library Extension (VLE) links. FICON channels are used for both host access (frontend) and real tape drive access (backend). VLE was introduced in VSM5 and offers a ZFS based commodity disk tier behind the VSM VTSS for storing data that requires longer residency on disk. Also, VSM supports a tapeless or disk-only solution for high performance requirements.
System capacity moves from 90TB (gosh that was a while ago) to now support up to 1.2PB of data. I believe much of this comes from supporting the new T10,000C tape cartridge and drive (5TB uncompressed). With the ability of VSM to cluster more VSM systems to the tapeplex, system capacity can now reach over 300PB.
Somewhere along the way VSM started supporting triple redundancy for the VTSS disk storage which provides better availability than RAID6. Not sure why they thought this was important but it does deal with increasing disk failures.
Oracle stated that VSM6 supports up to 1.5GB/Sec of throughput. Presumably this is landing data on disk or transferring the data to backend tape but not both. There doesn’t appear to be any standard benchmarking for these sorts of systems so, will take their word for it.
Why would anyone want one?
Well it turns out plenty of mainframe systems use tape for a number of things such as data backup, HSM, and big data batch applications. Once you get past the sunk costs for tape transports, automation, cartridges and VSMs, VSM storage can be a pretty competitive data storage solution for the mainframe environment.
The fact that most mainframe environments grew up with tape and have long ago invested in transports, automation and new cartridges probably makes VSM6 an even better buy. But tape is also making a comeback in open systems with LTO-5 and now LTO-6 coming out and with Oracle’s 5TB T10000C cartridge and IBM’s 4TB 3592 JC cartridge.
Not to mention Linear Tape File System (LTFS) as a new tape format that provides a file system for tape data which has brought renewed interest in all sorts of tape storage applications.
Competition not standing still
EMC introduced their Disk Library for Mainframe 6000 (DLm6000) product that supports two different backends to deal with the diversity of tape use in the mainframe environment. Moreover, IBM has continuously enhanced their Virtual Tape Server the TS7700 but I would have to say it doesn’t come close to these capacities.
Lately, when I talked with long time StorageTek tape mainframe customers they have all said the same thing. When is VSM6 coming out and when will Oracle get their act in gear and start supporting us again. Hopefully this signals a new emphasis on this market. Although who is losing and who is winning in the mainframe tape market is the subject of much debate, there is no doubt that the lack of any update to VSM has hurt Oracle StorageTek tape business.
Something tells me that Oracle may have fixed this problem. We hope that we start to see some more timely VSM enhancements in the future, for their sake and especially for their customers.
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Comments?
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Image credit: Interior of StorageTek tape library at NERSC (2) by Derrick Coetzee
