Set up in December after another major outage, a blog called GripeForce has been chronicling media coverage of the issue, along with the increasing frustration of "crmguy," who started the blog with, "All our sales data is trapped in there. How are we supposed to be productive when the site is always down!"

Although Salesforce has insisted that its availability rate is about 99 percent, recent glitches with a database software bug and other issues have caused downtime.

The outage on Monday prompted Salesforce to note that it understands customers get frustrated when service is not available and that the company is working on service improvements constantly.

Temporary Pain

Although Salesforce.com customers might be grumbling now, it is likely that most complaints will fade quickly once the company makes good on a plan to expand its number of data centers, said Forrester analyst Liz Herbert.

"They've been building additional data centers to handle the traffic, and they should be up and running very soon," she said.

Once the centers are operational, which could be within the next month, the type of incidents seen recently will be cut down to a minimum, Herbert noted.

Service Station

The complaints over Salesforce.com's outages highlight the importance of data-center management, but they also highlight another issue that is likely to crop up more frequently in the software-as-service world.

"Salesforce.com is one of the few on-demand companies that does not include service-level agreements as part of its contract," said Herbert.

That means customers who experience downtime are not eligible for any kind of compensation because the company had not made an uptime commitment.

Larger customers often are able to work with Salesforce.com to hammer out an uptime agreement, Herbert said, but often smaller companies, or those that do not involve I.T. in their on-demand decisions, are left with complaining on a blog as their only recourse in an outage.

"Because business users haven't had to deal with service-level agreements in their jobs, they might not even know what they are," said Herbert. "Then, if there's an outage, they'll be unhappy."