[Theory + Math] Long Term Storage Strategy

[Bob Zelin]

David writes –
The cheapest total cost over 15 years is to replace every 3rd year (2nd year was close too).

REPLY – hey, I agree with you. What do people do with all those DLT tapes, and SCSI and PATA drives (not to mention those iomega ZIP and JAZ drives). REPLACE every third year.

You know what the problem is of course – no one does this. Just like no one dumped their 1″ Tape libraries to Digi Beta (and then HDCam). They just sit on the shelf and rot.

Bob Zelin

[David Gagne]

Good to hear from someone who has been around long enough to see many generations of this… It’s helpful to have both experience as well as the math behind it showing that it makes sense to do this.

Of course the other piece of the puzzle is having good data-retention policies, but that’s a tough one to sell as well.

Bob, my thought is to make sure to be up-front with purchasers about this — and maybe even push for leased storage so that they get in the routine of renewing every third year. It’s helpful if they already have it marked on their calendar, “THIRD YEAR, TIME TO GET NEW STORAGE TO SAVE MONEY.” Also it’s helpful when purchasing — this purchase doesn’t have to last you forever, just for 3 years.

[David Gagne]

Here’s the link to my spreadsheet:

https://docs.google.com/spreadsheet/pub?hl=en_US&hl=en_US&key=0Ao_hE0x5R7SZdEhlY0lXVW80UGtVRTl1QlRYUVVFRkE&output=html

[Chris Gordon]

When you’re thinking of long term archival storage, don’t forget you need to make sure you have equipment and software that can actually read and use the data you’ve archived. Do you end up keeping your own inventory of parts and equipment to access the older formats or do you do data migrations to new formats? Both can be expensive. Also, don’t forget you need to periodically check the media and make sure everything is still ok on it. Over time there are various things that will happen that will render that digital archive useless. This can again, be expensive to do — periodically go through the media and make sure everything is ok, writing data to new media (may be same type, but just media that isn’t worn out from reads/writes) to be ahead of failures. Archiving can be very expensive well beyond just the cost of the media used.

As for 3 years, that is a very common “lifespan” for equipment. You find that after 3 years, failure rates will start increasing as things wear out. For equipment you buy support for, 3 years is often the initial term you can buy. After that you’re buying another round of support that is sometimes more expensive than buying new gear (not blaming a vendor selling support — if failures are far more likely, they need to cover that cost). At work, we put a 3 year life on the vast majority of the servers we buy. After 3 years of operation, we replace them. This helps avoid failures of aging machines, keeps with modern hardware that is supported by newer software, and is tied to our financials (depreciation schedules, etc). For some select gear, we use a 5 year schedule. These numbers are very common throughout the IT industry, so it’s not surprising that the numbers work out that way for your scenario.

But to your initial assertion, archiving is expensive especially when you have a constantly growing archive requirement. There’s no way around that. Storage has gotten far far cheaper over time, but if rate of your archive growth is greater than the rate of storage cost reductions, you’re on the expensive side of the equation.

Chris