Glenn, I work for one of the three vendors, and so I am very surprised to hear that HDS thinks that "Tape is clearly the best storage media for long term data archiving." Would you happen to know who it is that represents HDS hardware/software that agrees with this? I for one strongly disagree with the statement.
Why would you suggest that CU tiering is only for small environments? I'm thinking the large, multi PiB environments will gain far more from storage tiering than smaller to medium shops. They have far more to gain from removing the overheads of Primary and Secondary space management and the costs of recalls, especially when they can take advantage of commodity midrange storage for inactive data. This is the same storage that makes virtual tape so attractive, but without the cost of redundant data movement and transformation. The two single greatest changes in DFSMShsm in recent times have been CRQ and Transitioning, where CRQ acknowledges the problems of managing large scale HSM activity, and transitioning is a kludge that allows DFSMShsm to take advantage of CU based tiering. In fact I think I spoke to you in San Francisco about the possibility of replacing the transitioning command with a proprietary migration command if the vendor had a way to do command level tiering of a data set extents rather than FlashCopy. The DFSMShsm ML2 strategy decrees that data can no longer be directly accessed when it becomes inactive or dormant. Why is that a better strategy for Information Lifecycle Management than allowing the data to be accessed directly even as it moves to a more cost effective media as it ages? Why is last accessed a date a better strategy for archiving data than the backend IO/hour? Why can't I archive 100s of TBs of data because someone keeps opening the file but not touching the data? I agree that "Each tiering technique, hardware and software, has strengths and weaknesses" but I earnestly feel that the archiving controls afforded DFSMShsm do not lend themselves to good storage cost containment. I acknowledge again that ML1 and disk based ML2 can operate very effectively in a tiered storage environment, especially where ML2 can transparently migrate to commodity midrange storage as it ages. I do not however agree that the cost of data translation and recall are necessary to maintain good ILM strategies. I still remember the Iceberg pundits from STK describing how there would be a Nearline library behind every Iceberg and HSM would disappear. I think we are getting closer to this every day and many shops are in a position to do exactly that. Ron -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Glenn Wilcock Sent: Tuesday, August 26, 2014 10:05 AM To: [email protected] Subject: [Bulk] Re: [IBM-MAIN] [Bulk] Re: [IBM-MAIN] General question on moving DFHSM work from mix TAPE/DASD to More DASD While control unit storage tiering may be considered as a replacement to HSM processing for smaller environments, such a recommendation is an over simplification of the need for a comprehensive ILM strategy to properly manage data in middle-to-large environments. At the various conferences that I attend each year, this concept was originally discussed when cu tiering was first introduced, but after discussions, all three vendors see the value of HSM ILM and cu tiering being used together to create a powerful solution as opposed trying to select one over another. Each tiering technique, hardware and software, has strengths and weaknesses. Using each technique to its strengths provides tremendous opportunity as we move forward with managing the significant growth of data that we are seeing. In z/OS V2R1, DFSMS introduced its initial Storage Tiering solution. This offering lays the framework for z/OS's long term strategy to provide various ILMs solutions so that clients can implement the ILM solution that works best for them. An integral part of this strategy is to move away from ML1 and move toward an L0 - Ln, ML2 solution. Tape is still clearly the best storage media for long-term data archiving, and all three vendors will agree to that. I am currently working with clients to move to an L0 - Ln, ML2 environment, and it is exciting to see the opportunities that exist by integrating software and hardware tiering into a single, powerful ILM strategy. I'm more than happy to meet with clients to discuss the V2R1 DFSMS Storage Tiering solution and discuss the opportunities that it provides to exploit the strengths of the two types of tiering. Glenn Wilcock DFSMShsm Architect ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
