Dantz: Adaptec SCSI Cards Unreliable With Retrospect & OS X

Dantz, the makers of Retrospect, recently released information on its support site that covers Mac OS X SCSI host adapter compatibility. They list brands like ATTO Tech, Initio, AdvanSys and Orange Micro but not Adaptec, the company that owns the largest percentage of the Macintosh SCSI market.

The page specifically warns that "Ongoing testing by DantzLab has found that Adaptec SCSI cards do not function in a consistent, reliable manner when used with Mac OS X." It also states that the problem isnit specific to any application or version of OS X. " The problem, which affects all versions of Mac OS X including 10.2 (Jaguar), is not application specific. Rather, incorrect data is passed by the SCSI card to and from any program communicating with a SCSI device. The result may simply be an inaccessible device, or worse, data corruption can occur."

Despite Dantzis claims, there is no mention of any such problem on either Adaptecis Mac OS X Compliance or support Web pages. Chris Schultz, marketing manager for Adaptecis Desktop Solutions Group told TMO that the Ultra 160 line of SCSI cards work acceptably with most applications under OS X. "Adaptecis currently released Ultra160 SCSI product line has been successfully tested with a broad range of Macintosh OS-X applications." Adaptec has also successfully tested their 2930U and 2906 cards in the new operating system. Schultz addressed the Retrospect issue specifically by stating that it "presents a unique environment with heavy I/O requirements."

The input/output demands of Retrospect, which can be quite heavy, should not cause the problems being reported to Dantz by hundreds of customers using tape and CDRW devices. According to Eric Ullman, technical marketing representative from the Dantz Development Corporation, "Supported SCSI cards donit exhibit this behavior, even when placed under the same iheavy I/O requirements.i"

He goes on to explain the technical details further, saying "...Retrospect accesses all SCSI devices through Mac OS Xis SCSITaskUserClient API. This is a high-level API that accepts SCSI commands like read, write, reposition, eject media, etc. At no time does Retrospect speak directly to a device or to a SCSI card; only high-level interaction takes place. What is happening with the Adaptec 160 line is data offset errors are returned during verification, meaning that the data actually written (or read)?doesnit match what was sent."

Both companies agree that there is a problem using Retrospect with Adaptec SCSI cards under OS X and state they are working closely with each other to remedy the problem. "Adaptec is firmly committed to supporting the Retrospect offering and is planning to provide a solution in the next revision of the drivers," says Schultz. The estimated timeframe for that next revision is during the first business quarter of 2003 and until that time, Dantz refuses to recommend or support the combination.

Apple declined to comment on this issue.