On 27 Aug 2014 09:30:27 -0700, in bit.listserv.ibm-main you wrote: >Hi Ron, > >I agree with everything that you say about cu tiering, except for the fact >that a migration tier is no longer necessary. CU tiering is an exciting new >storage opportunity for ILM. I'd like to discuss this topic with you the next >time that you attend SHARE or the Technical University. I've discussed this >topic with your colleagues from HDS and also those from EMC. Let me go into >more detail on some of the questions that were raised. > >- I don't recall (pun intended) specific individuals that I've discussed >tape/disk with, but HDS presentations on Tiering at SHARE show data moving to >ML2 for archive after it has gone through the L0 - Ln disk tiers. These >presentations also highlight the value of software / hardware tiering on a >slide or two. Industry charts that show cost comparisons of cost/GB of >storage show the clear cost value of tape. >- I didn't mean to say that cu tiering is only for small environments. I was >communicating that I believe that only small environment could eliminate a >migration tier. CU tiering is of value for all environments. There is a >finite amount of data that can be online to z/OS because of the UCB >constraints. To eliminate the migration tier, you have to uncompress and >return all migration data to online UCBs. That may be an option for smaller >environments, but I don't see value in having uncompressed, archived data >sitting on online disk, and large environment physically can't do that because >of the limit to the amount of data that can be online.
What is the largest size 3390 that can be defined? As someone who is in possession of multiple 1 and 2 terabyte portable disks for his PC I would hope in this day and age, the answer is in terabytes. If not the idiots who wouldn't spend 26 million to allow FBA on MVS have created a disaster. Clark Morris >- DFSMShsm Transitioning is not a 'kludge' but rather a strength. Strengths >of cu tiering 1) transparent 2) works on open data 3) no host MIPS. Strengths >of Transitions 1) Data set level 2) Business policy based 3) Works across CUs. > Weakness of cu tiering 1) movement done on heatmap with no understanding of >data's business value. Weakness of transitions 1) data must be quiesced. Cu >transitining weaknesses: I reorg a DB2 object. The data that had been >fine-tuned to the correct tier is now scrambled across multiple tiers and >until the cu relearns the correct tiers, I suffer subpar performance. Also, >in the presentations that I've seen, CU tiering is appropriate for data that >can be learned, like database data. It is not good for data like Batch data. >(Once again, look at the HDS presentations on tiering). >- The example that I have used for combining the two technologies that HDS has >included in their Tiering presentation: 3 Tiers: T0 is SSD and Enterprise >disk. T1 is Enterprise and SAS. T3 is Migration. Newly allocated data goes >to T0. Cu tiering moves the data between SSD and Enterprise based on heat >map. After a policy-based amount of time, the data has diminishing business >value and HSM transitions it to T1. Data remains on the lower cost T1 while >it is still active and the cu moves the data between Enterprise and SAS based >on heat map. After the data goes inactive and should be archived, HSM >migrates it to the migration tier. The migration tier can be all ML1, >ML1/ML2, ML2 Virtual with all disk, ML2 Virtual with a combo of disk and tape, >or all tape... whatever is best for each client's environment, as each has its >strengths. >- If you reference my presentations on tiering, I have been a proponent of >eliminating multiple migration tiers for years. I have been recommending that >customers use CU tiering for online tiering and that they don't migrate data >until it really goes inactive, and then send it to a single migration tier. >Until recently, I ML2 was the best choice because you get the compression for >free on the tape cu (virtual or real). In this quarter, HSM is shipping >support for the new z compression engine. That provides very high compression >ratios for data on ML1, without using MIPS for compression. So, that now >makes ML1 attractive also, for those customers who want a tapeless >environment, like those on this thread. >- There is a clear cost value to tape. If a client can afford to have all of >their data uncompressed on online disk and don't have to worry about the UCB >constraints, then more power to them. But, I suspect that most clients are >still looking to keep their storage costs to a minimum. > >Our strategy is to provide all the options so that clients can select the ILM >strategy that best needs of their data. Integrating the strengths of CU >Tiering with Software Tiering provides the best of both worlds. > >Glenn > >---------------------------------------------------------------------- >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
