I have always done manual forecasting with Excel. The first thing to get a handle on is your TSM growth rate - the TSM accounting records are very useful for this. Another problem with TSM is that every environment is so different.
Here is a vanilla example of how you could do things: 1. Total up your onsite tape storage pools space used, total number of onsite tapes used, and a typical max capacity number you see for your type of media. Use these numbers to figure out what is the avg % utilized across all tapes - 60%-70% would be typical. i.e. 10,000GB total in onsite tape pools, using 100 LTO onsite tapes, assuming max capacity of 200GB compressed for LTO equals 50% average tape utilization. 2. Do the same thing for offsite tape storage pools - will probably be a little less avg % utilized per tape. You'll have tapes pending and reclamation thresholds might be higher for offsite pools. 3. Figure out your average growth rate i.e. if last month your onsite pools were 10TB and this month they are 10.5TB, then you are growing 5% per month. Try to trend this over as long as period as possible to get a more accurate average growth number. I find yearly growth rates to be a little more accurate. Will greatly depend on how far back your accounting records go. 4. Now just take your monthly or yearly growth rate, avg tape utilization %, and current size of storage pools and use those numbers to forecast out x number of months. i.e. use Excel to make the calculations for you as to how big your storage pools will be x number of months out from now. Then just use your average tape utilization number and tape capacity to figure out how many tapes it will take to cover that much tape storage pool space growth. i.e. Using my sample 50% avg tape utilization number from step1, assume that the forecast shows onsite tape storage pools to be 15,000GB 6 months from now, meaning 5,000GB in growth. That will require an additional 50 tapes just to cover the onsite data growth. Assuming your offsite tape utilization is a little less, then that would mean more than 50 tapes to cover the offsite tape growth that will happen also. This doesn't count archives, backup sets, or anything else you may be doing. Typically scratch tape counts, tapes in transit (pending status), DB backup tapes, etc. remain fairly constant over time so I don't really factor those in unless it is a brand new TSM customer. 5. If you do anything else special like archives, backup sets, etc. you could also use a similar method to calculate your growth rate there as well. It really depends on how often people want to buy tapes as to how far you forecast out. These estimates will also vary greatly on how accurately your past growth rate determines your future growth rate. But I find this to be about the closest you can get without using any 3rd party tools, and usually gets you within 5-10% of the tape number actually needed. The most I have ever gone out was 18 months and I have found the farther out you try to forecast the less accurate you will be. This method should get you really close for forecasting out 6 months at a time though. Should be good enough to do yearly budget numbers too (if you add in a little puff). ______________________________ John Monahan Senior Consultant Enterprise Solutions Computech Resources, Inc. Office: 952-833-0930 ext 109 Cell: 952-221-6938 http://www.computechresources.com "Etchison, Jim (SBS US)" <[EMAIL PROTECTED] To IEMENS.COM> [email protected] Sent by: "ADSM: cc Dist Stor Manager" Subject <[EMAIL PROTECTED] Tape Usage Forecasting .EDU> 08/12/2005 02:11 PM Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED] .EDU> Greetings, This is my first posting to this list, so please forgive me if this is not the right type of question or the right group to ask. I am currently a Client Manager for a large corporation that uses TSM as its backup solution. TSM seems to be working very well for my client, with one glaring exception: tape usage forecasting. On a number of occasions I have had to "surprise" my client by telling them they needed to buy thousands of more tapes. The first few times this has been forgiven, but with each successive request, they have gotten more and more irritated. From what I have been told by my Storage Manager, TSM does not have any Tape Forecasting capabilities. But from a business standpoint, this is a very real need because it is a substantial cost. At this point I am left with no option but to continue suprising my customer, which is not a career-enhancing choice. :) My question is this: how have others resolved this dilemma? Is there an add-on product that can be purchased that might solve this? Any help would be welcome. Thanks!
