Washington - Some technical experts are perplexed at the US government's plan to switch web hosts for its new health insurance portal, HealthCare.gov, in the midst of an expected last-minute rush to beat an enrolment deadline of 31 March for 2014 coverage.Switching hosts is not in and of itself a huge risk if it is done carefully and with lots of preparation, according to technical experts interviewed by Reuters. It is the timing of the highly complex manoeuvre that is risky. If there are problems, the website could become sluggish or even unusable for anyone trying to enrol.The government is tempting fate, they said. It already has a poor technological track record in carrying out US President Barack Obama's signature health law, the Patient Protection and Affordable Care Act, which is intended to provide millions of uninsured with medical coverage.HealthCare.gov, an important component of the reform, was plagued by technical problems when it opened for insurance enrolments on 1 October and it has taken weeks of repairs to nurse it back to almost full health. It is still not functioning 100%.If the switchover between web hosts does not go smoothly, that could feed already negative perceptions among many people about the law known as Obamacare. The problems with the website have generated weeks of bad headlines, and polls show the negative publicity has weakened people's confidence in the initiative.TransitionThe timing of the change in host services "is nonsensical in all dimensions", said Peter Neupert, who managed similar transitions when he ran drugstore.com, a website he took public in 1999, and while working as a corporate vice president at Microsoft."Why would you plan for a big transition six months after going live?" said Neupert, now an operating partner with Health Evolution Partners, a private equity firm that invests in health companies.The government agency in charge of running HealthCare.gov says it is "working to ensure a smooth transition" to Hewlett-Packard from Verizon Communication's Terremark subsidiary.HP has successfully performed similar data centre transitions for Medicare.gov and another Medicare fee-for-service claims processing operation, a Centres for Medicare and Medicaid Services (CMS) official said.Technical experts were able to provide some insight into what was happening behind the scenes. The work involved in switching data centres is similar to the weeks of preparation required for moving a company office.First, HealthCare.gov will need to be rebuilt or "mirrored" at the new site, and then tested extensively to make sure all the new servers are properly configured, said John Engates, chief technology officer at web hosting firm Rackspace Hosting, a competitor to Terremark and HP."The data has to move, the code has to move, everything has to be sort of rebuilt at HP now to the same level of capacity and standards," he said.UndetectableIf a website's architecture has not been set up for the seamless movement of data between multiple locations then it may also need "significant programming and redesign of software," said computer architecture expert Onur Mutlu of Carnegie Mellon University in Pittsburgh.If the switch goes smoothly, the experts said it could be done during a planned outage on a weekend evening, undetectable to consumers trying to sign up for insurance.But if it does not go well, one only has to look back to 27 October to see the potential consequences, when a glitch within the Terremark server running HealthCare.gov brought down the site for several hours, preventing customers from enrolling.Along with UnitedHealth Group's QSSI, the company serving as the general contractor for HealthCare.gov repairs, the contractors are looking at developing parallel operations for the transition to ensure consumers can continue to use the site when the switch is made, the CMS official said.Problems with switches in data centres happen from time to time in the private sector, although they are not widely advertised, the experts said.Like an office move, "nothing ever works perfectly once you get to the new place", Engates said. "The phones sometimes don't work yet."