updated 11:59 pm EDT, Tue July 10, 2012
Should affect only 0.5 percent of users' email
Apple has posted on its iCloud status update page that it will have a brief period of planned maintenance to its free iCloud service between the hours of 10 p.m. and midnight Tuesday (Pacific time, 1-3 a.m. Wednesday Eastern time). The company says that only one-half of one percent of users should be affected by the outage, which will cause some users to be unable to retrieve email.
Users of iCloud have seen small-scale outages of some services periodically since its introduction, but this will mark the first time a deliberate service interruption has been planned since the shutdown of iCloud's predecessor, Mobile Me. Though generally quite reliable in recent years, Mobile Me experienced many small- and large-scale disruptions in its early days in mid-2008, prompting an unprecedented apology and a total of a three-month free extension of service to its paying customers.
The transition and takeover of iCloud has generally been seen to be much smoother, even though Mobile Me eventually grew to have millions of subscribers that needed to be switched over. Apple has seen strong growth in iCloud adoption, with the last public figure reaching over 120 million users. Adoption has no doubt been helped by the reduction in the cost of the service (from $100 per year to free) and the continuation of practical benefits such as "Find My iPhone" and other services like syncing that offer obvious advantages to owners of multiple Mac and iOS devices.
Though iCloud dropped several services (such as photo/video and website hosting) that had been popular with a portion of the Mobile Me base, the company continues to add modest features to iCloud. Recently, the iOS version of iPhoto implemented a form of iCloud-hosted photo-sharing called Photo Journals along with the existing Photo Stream syncing, and the forthcoming releases of OS X 10.8 (Mountain Lion) and iOS 6 will expand the use of iCloud for document storage and syncing, though Apple does not look to be taking on cloud storage competitors such as Dropox and Microsoft's SkyDrive directly.
The last (unplanned) service interruption for iCloud was on June 20, where services were offline (for some users, but not all) for a little over two hours late in the evening (or early in the morning on the east coast). On average, some form of minor disruption has been reported by Apple about once a month.