The climate-controlled room whirrs with electronics. A digital recorder copies a 46-year-old video of the trial of Nazi war criminal Adolf Eichmann. Other machines digitize audio testimonies taped by Holocaust survivors. Microfilmed war documents flash across a digital scanner at two images per second, or 5 million a month.

Israel's Yad Vashem Holocaust Memorial is getting its huge archive ready to go online.

In Washington, the U.S. Holocaust Memorial Museum is reproducing its own millions of pages of wartime records in digital format.

One more archive — perhaps the mother lode from history's worst genocide — is missing.

In the German town of Bad Arolsen, technicians are scanning the largest closed collection of Nazi documents, sheet by sheet. The archive is managed by the International Tracing Service, created by the International Committee of the Red Cross in the chaotic aftermath of World War II to track down missing persons and help reunite families.

The ITS files comprise the most complete record on Nazi victims. Its estimated 50 million pages of concentration camp papers, death lists, transport documents and postwar displaced-persons folders contain the names of 17.5 million murdered or persecuted people — about one-fourth of them Jews.

After years of pressure from victims groups and from the United States, the 11 nations that govern the Tracing Service decided in May 2006 to make them accessible for the first time to researchers and to survivors. Each country's national archive would be offered electronic copies.

That decision cheered aging survivors, who believed they finally might find clues to the fate of friends, old neighbors and entire villages that vanished in the Nazi inferno.

But their mood turned angry when they learned that the decision required ratification by all 11 countries — a process expected to be completed only later this year. Even then, they still won't be able to browse the files freely. Instead, staff will search for material they request.

"Such an arrangement falls far short of genuine open access," said the Holocaust Survivors' Foundation, based in Miami, Fla. Survivors want to see the records "with our own eyes and on our own terms."

The archivists in Jerusalem and Washington defend their colleagues in Germany, citing an array of legal and technical problems.

Sara Bloomfield, director of the U.S. Holocaust Memorial Museum, which will receive a copy of ITS' archive, said critics "grossly oversimplify accessibility." At Yad Vashem, which will receive Israel's copy, information technology chief Michael Lieber says the documents are simply too disorganized.

"Even if the member states resolved to put it on the Internet, there wouldn't be much point," he said. "There is no tool available for people to handle it themselves."

But Fred Taucher, a computer specialist in Seattle, is 74 and impatient. Over the years, he has tried unsuccessfully to get answers directly from the Tracing Service about his relatives, but was told each time that the backlog of inquiries was too big.

"I have been waiting 20 years to know what happened to my family. Only I and my brother survived. I lost my mother, father, and lots of aunts and uncles — in Auschwitz, I think," he said, reached by telephone.

Taucher was 12 when he was arrested on a streetcar in 1945 and sent to Dachau "on the last cattle car from Berlin" before the end of the war, but he escaped en route. Now, he wants to see what the Nazi files say about him.

One problem for Bad Arolsen is legal. The 2006 agreement says receiving countries must "ensure adequate protection relating to personal data" and block access to sensitive information about the victims.

Then there's the ITS' system. Unlike a library's alphabetized card index, ITS' Central Name Index of 40 million cards has many duplicated names with variations, usually filed according to the German phonetic spelling.

All but 3 million are written by hand, many in German script, and aren't machine-readable.

Still, the ITS is scanning its files at an increasing pace. The first batch of 13 million pages of concentration camp records — enough data to pack 8,000 CD ROMs — will be transferred in September. It will take until 2009 to finish the job.

Most of the documents were seized after the war from concentration camps, collected from town records and from Nazi offices. The index cards give indications of where files may be found, but the archive has been reorganized so many times that the cards are often useless in pinpointing actual documents. Drawing on memory and experience, veterans among the 380 ITS staff have the best chance of tracking them down.

Starting well before the computer age, ITS has responded to 11 million requests to locate family members or to support applications for reparations and pensions. It says its success rate in finding names is about 56 percent.

The Associated Press has been given extensive access to the archive to report on its contents. With permission from the families, the AP submitted several names to be searched, including birth dates and last known locations. None was found.

Nearly 65 years after the war, Yad Vashem still receives 20,000 requests a year for information about individuals. The Washington museum and ITS each gets about 8,000 inquiries.

But many names are missing, likely gone forever. The Nazis destroyed millions of records as the Third Reich was collapsing. The names of others in Eastern Europe may have disappeared during the secretive Soviet era, though records are still being recovered and sent to Jerusalem and Washington.

Taucher, who runs a technology consulting company, says he understands the problems in converting the Bad Arolsen files to computer data, but believes at least the names and places of victims should be made available on the Internet.

"Yes, it's going to take time," he said. "I believe it can be done."