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I'm in the Malev lounge at the Budapest Airport, waiting for my flight to return back to Tucson.
Back in the late 1980's and early 1990's, I was one of the architects for DFSMS on z/OS, and customers always asked, "What is the clip level?", in other words, how big does a customer have to be to take advantage of DFSMS. We worked it out that if you had more than 100GB of disk data, DFSMS is worthwhile. DFSMS is now just standard by default, as everyone now easily has more than 100GB of data.
Later, in the late 1990's, I worked on Linux for System z. Again, customers asked how many Linux guest images would justify deploying applications on a mainframe. We worked it out to about 10 images. 10 Linux logical partitions, or Linux guests under z/VM was enough to cost justify the entire investment.
So what is the "clip level" for SANs? How many servers does an SMB need to have to justify deploying a SAN? IBM announced the new BladeCenter S designed specifically for mid-sized companies, 100 to 1000 employees, typically running 25 to 45 servers. However, I suspect companies as small as 7-10 servers would probably benefit from deploying an FC or IP SAN.
What do you think? Send me a comment on how many servers should be the clip level.
A client complained that their tape drives were not compressing data as well as it used to. Investigating further reminded me of a scene from the 1970's television show "All in the family", summarized well inAmerican Scientist:
... in one episode of All in the Family, Archie Bunker's son-in-law, Mike, watches Archie put on his shoes and socks. Mike goes into a conniption when Archie puts the sock and shoe completely on one foot first, tying a bow to complete the action, while the other foot remains bare. To Mike, if I remember correctly, the right way to put on shoes and socks is first to put a sock on each foot and only then put the shoes on over them, and only in the same order as the socks. In an ironic development in his character, the politically liberal Mike shows himself to be intolerant of differences in how people do common little things, unaccepting of the fact that there is more than one way to skin a cat or put on one's shoes.
Both agreed that socks go first, then shoes, but the actual deployment was different.
In the case of this customer, a recent change was the use of "encryption" before the data reached the tape drive. In regards to compression and encryption, you should always compress first, then encrypt. Compression algorithms rely on frequency of data, for example the letter "E" appears more often in the English language than the letter "Z". However, once you encrypt data, those data patterns are randomized, and any attempt to compress the data afterwards is wasted effort.
With IBM tape encryption on either the TS1120 or LTO4 tape drives, we compress, then encrypt, the data when it arrives to the tape drive, so that the compression has some chance of getting up to 3:1 reduction. This comp So, just as the case between Archie Bunker and his son-in-law, there are many ways to deploy compression and encryption, just make sure you do them in the right order to get the most benefit.
So, just as the case between Archie Bunker and his son-in-law, there are many ways to deploy compression and encryption, just make sure you do them in the right order to get the most benefit.
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This week I am off to Budapest, Hungary, for business meetings. It is the closest major city to IBM'smanufacturing plant in a small town called Vac (rhymes with "knots") where the IBM System Storage DS8000 seriesand SAN Volume Controller are assembled.
Last week, I opined that Monday's IDC announcement "IBM #1 in combined disk and tape storage hardwaresales for 2006" was in part because of a resurgence of interest in tape, with four specific examples. There was a lot of reaction and reflection fromboth sides.
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One of the differences between IBM and the other storage vendors is that IBM is also in the business of middleware, application-aware backup software, and advanced copy services. This allows IBM to put togethersolutions that work to address specific challenges for our clients.
IBM has written a whitepaper on a cleverVSS Snapshot Backup for Exchange using IBM Tivoli Storage Manager and the point-in-time copy capabilities of IBM System Storage disk systems.
A problem in the past was that each vendor's point-in-time copy method had its own unique proprietary interface.Microsoft Developed Volume Shadow Copy Services (VSS) as a common interface front-end to resolve this concern.IBM Tivoli Storage Manager for Mail can invoke standard VSS interfaces, and this in turn can invoke FlashCopyon the IBM System Storage SAN Volume Controller, DS8000 series, or DS6000 series disk system.
You might be thinking: Wouldn't it have been less effort to just have TSM for Mail invoke IBM proprietary interfaces,rather than having to put full VSS support into TSM for mail, and then full VSS support into IBM's various disksystems? Perhaps, but IBM doesn't decide to do things because it is the cheapest way, we focus on what is theright way, and in this case, customers now have more choices, then can use TSM for Mail with IBM or non-IBM disksystems that support the VSS interface, and IBM disk systems can be employed into other uses for VSS snapshot.
Of course, we would like our clients to consider both TSM and IBM System Storage disk systems for a combined solution,not because they are required to make the solution work, but because both are best-of-breed, and whitepapers likethis show how they can provide synergy working together.