Mozy, the online backup service provider and EMC subsidiary, plans to announce today that it's dumping its subscription permitting customers to store unlimited data.

The reason is not hard to guess: with ever-growing quantities of photos and videos, the unlimited plan is financially unsustainable, the company said. In other words, it's my fault.

You see, I'm a Mozy customer. I spent $82 for a two-year subscription and started inflicting my hundreds of gigabytes of photos and increasingly videos as well. I'm a photo nerd, so each 21-megapixel photo in raw format sucks up something like 20MB or 25MB, and each video is shot in 1080p so even shortish clips can occupy a half a gigabyte.

I'm somewhere in the top 0.3 percent in terms of my data use, but I'm also a leading indicator, and that's why Mozy is altering course.

"There has been a change in consumer behavior," said Russ Stockdale, Mozy's vice president of product management. "What we have seen since we launched an unlimited service five years ago is there has been an explosion in digital content, specifically digital photos and video."

In my case, with just under 600GB of data, the $3.40 per month I pay now will explode to just about $60 per month when my subscription runs its course in a few months.

That's because Mozy will begin charging $5.99 per month for up to 50GB of data, with more costing $2 per month per 20GB after that. And, recognizing that more and more people have multiple computers to back up, it's added a new multi-machine option costing $9.99 a month for up to 125GB and three computers. More computers or further 20GB increments add another $2 per month each.

Good-bye unlimited Needless to say, I'm now looking at Mozy alternatives. But I don't feel resentful--just sad at the disappearance of yet another uncapped part of the Net.

I'm grandfathered into an unlimited-data plan with T-Mobile UK, but if I leave to try to find a carrier with better service, they don't have an unlimited plan for me, and I can't go back to the T-Mobile plan. Likewise, my unlimited home broadband account actually has fair-use limits, as is customary in the U.K. My $25 a year at Flickr gets me unlimited photo storage, but it's something of a holdout in an increasingly pay-as-you-go world.

And Mozy isn't alone. Google Docs costs $1,400 a year for 400GB, for example, and Google's Picasa Web Albums costs $100 per year for 400GB. Jungle Disk, which provides a front end to storage using Amazon's S3 service, charges $3.15 per gigabyte per month. Carbonite, perhaps Mozy's best-known competitor, throttles down bandwidth for big-data users. And up-and-comer Dropbox charges $20 per month for 100GB.

Here's Mozy's rationale for the change: the average storage per user increased more than 50 percent last year. More than half of the growth, though, was with the top 10 percent of the users, as measured by how much data that they have.

"The great majority of customers are growing at manageable levels, while the heaviest users bring up the average for the entire group," Stockdale said.

Mozy braces itself The company knows it's in for some ill will.

"We do not take this on lightly...I don't expect everybody to be happy about it. But if they take a look at what we're doing and why, it'll at least be understandable," he said. Mozy is trying to make the change so it can provide sustainable high-quality backup in the long term" and not resort to fine-print shenanigans hoping few will notice.

The unlimited plans come to an end starting March 1, but last through the end of each customer's paid subscription.

Not all of Mozy's costs are going up. Hard drives can hold ever more data for a given price (2-terabyte drives can be had for $100 these days). But that's not enough to deal with Mozy's financial plight, Stockdale said.

"The cost of storage is an element, but it is not even the majority of cost of providing the service," Stockdale said. "The bandwidth, the data centers, the people who manage that--those costs are a larger part of the cost of providing this."

Mozy, though a subsidiary of storage powerhouse EMC, uses its own software running on commodity storage systems. Later this year, though, to it'll start moving users to EMC hardware and eventually migrate everyone, Stockdale said.