Microsoft yesterday unveiled details of Windows Home Server's first feature update, dubbed Power Pack 1. Microsoft said it does not know when it will finish a patch for a data corruption bug that has been scrambling files on Windows Home Server.

Joel Sider, a senior product manager for Windows Home Server, said that the update, dubbed Power Pack 1, will ship "sometime this spring". It will be the first feature enhancement upgrade to the home server operating system, which launched last August.

Among the new features, said Sider, will be support for home PCs running 64bit versions of Windows Vista, server backup and restore, more granular access privilege settings and multi-file upload and download. "The feedback was neck and neck between Vista 64bit support and the backup and restore," said Sider. "They were definitely the top two requests."

Although the "Power Pack" label is one Microsoft rarely uses to describe an update - "Service Pack" is more common for the company - Sider said another way to think of it is as a minor upgrade in Microsoft's previously-announced alternating minor and major OS updates. "We also wanted to have a name that was kind of fun, in keeping with the product, and one that also said we were turbo-charging Windows Home Server," he added.

The new server backup - a backup of the backup - has been among the feature requests posted by users on Microsoft's support forums since before Windows Home Server shipped. Power Pack 1 will let users back up portions of the server. "Users will be able to select folders or specific files," confirmed Sider, "whatever they want to offload."

The backup and restore feature will also back up the operating system software, so that in the case of a unrecoverable crash, the server will not have to be restored from the original install media.

But while Microsoft had plenty of information to share about Power Pack 1, it had no news on the patch for the data corruption bug that it disclosed the week before Christmas.

The bug could hash files edited with Windows Vista Photo Gallery, Windows Live Photo Gallery, OneNote 2003, OneNote 2007, Outlook 2007, Microsoft Money 2007 or SyncToy 2.0 beta, Microsoft said several days later, only when the server is also occupied with copying large files.

More than a week ago, another Windows Home Server product manager, Todd Headrick, promised that the team would work around the clock on a fix. Monday, however, Sider declined to set a timetable for its release.

"We still have no ETA," he said. "The team is working diligently, but the real key here is testing." When the patch is finished, it will be posted to Microsoft's download site, and pushed out automatically to all Windows Home Server users.

In the meantime, Microsoft has urged users not to use the listed applications to save or edit files stored on a Windows Home Server-powered machine.

Sider also declined to share sales figures for Windows Home Server, citing company policy. He said only that it had sold the home server software to users in more than 30 countries, and that Hewlett-Packard's MediaSmart Server (reviewed here), the first OEM-produced hardware that uses WSH, had been "a best seller right out of the gate" on when it launched last month.

The HP server is sold in two versions - a $599 box with 500GB of storage and a $749 model with 1TB of disk space - and should reach retail store shelves this week, Sider said.