Dick Benton of Glasshouse Technologies has an article on SearchStorage.com titled Justifying your storage staffing.
The concept that there should be a linear "Storage Administrators per TB" rule-of-thumb has been around for a while.Back in 1992, I went to visit a customer in Germany who had FIVE storage admins for 90 GB (yes, GB, not TB) disk array.I told them they only needed 3 admins, but they cited German laws that prohibited "overtime" work on evenings and weekends.
Later, in 1996, I visited an insurance company in Ohio to talk about IBM Tivoli Storage Manager. They had TWO admins to manage 7TB on their mainframe, and another 45 people managing the 7TB across their distributed systems running Linux, UNIX, and Windows. My first question, why TWO? Only one would be needed for the mainframe, but they responded that they back each other up when one takes a 2-week vacation. My second question to the rest of the audience was... "When was the last time you guys took a 2-week vacation?"
Today, admins manage many TBs of storage. But TBs are turning out not to be a fair ruler to estimate the number of admins you need. It's a moving target, and other factors have more influence that sheer quantity of data.Let's take a look at some of those factors, which we call "the three V's":
- Variety of information types
In the beginning, there were just flat text files. In today's world, we have structured databases, semi-structured e-mail systems, hypertext documents, composite applications, audio and video formats that require streaming, and so on. Variety adds to the complexity of the environment. Different data requires different treatment, different handling, and perhaps even different storage technologies.
- Volume of data
Data on disk and tape is growing 60% year on year. It's growing on paper also. It's growing on film like photos and X-rays. The problem is not the amount, but the rate of growth. Imagine if population and traffic in your city or town increased 60% in one year, most likely people would suffer because most governments just aren't prepared for that level of growth.
- Velocity of change
Back in the 1950's and 1960's, people only had to make updates once a year, scheduling time during holidays. Now, people are making changes every month, sometimes every weekend. One customer we spoke with recently said they do about 8000 changes PER WEEKEND!
So, the key is that there is no simple rule-of-thumb. Fewer admins are need per TB on mainframe than distributed systems data. Fewer admins per TB are needed when you deploy productivity software, like IBM TotalStorage Productivity Center. Fewer admins per TB are needed when you deploy storage virtualization, like IBM SAN Volume Controller or IBM virtual tape libraries.
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