James,

After updating my production copy of Qrecall to the latest beta (1.2.0 Beta 6) one of my archives got corrupted. I'm not sure if it is directly related or just a coincidence.

During the required "repair" operation I have received multiple "Transient data read error; re-reading the same data was successful" errors.

Do you automatically re-write the data to a new location on disk to prevent future transient data read errors? If not, is there an option to force you to as those areas on disk are not most likely to go bad so I would like to have the data relocated to a safer place.

Regards,
Wayne

Wayne Fruhwald wrote:After updating my production copy of Qrecall to the latest beta (1.2.0 Beta 6) one of my archives got corrupted. I'm not sure if it is directly related or just a coincidence.

Your guess is as good as mine.

During the required "repair" operation I have received multiple "Transient data read error; re-reading the same data was successful" errors.

When QRecall reads a block of data and finds it to be corrupted, it requests a second (unbuffered) read from the drive to a different RAM location. If the second read returns uncorrupted data, it logs the message you are seeing and continues.

This message means that the data on the drive is, more than likely, OK and that the data is being corrupted somewhere "in the pipe." The data could have been mis-read from the media, scrambled during transfer through the interface (USB/Firewire/eSATA), or could have been dinged by bad RAM.

If this message persists, I would suggest a thorough RAM diagnostic. This wouldn't be the first time that bad data was caused by failing RAM. I would also try to test the drive using a different interface (i.e. switch from Firewire to USB), if that's an option, and see if the errors go away. It's also instructive to notice if the file location associated with the error changes. If the problem persists at the same location, it would point to a media problem. If it changes, then it would indicate transient corruption elsewhere.

Do you automatically re-write the data to a new location on disk to prevent future transient data read errors? If not, is there an option to force you to as those areas on disk are not most likely to go bad so I would like to have the data relocated to a safer place.

Sector sparing is now the purview of modern drive controllers. This should be done automatically by the hard dirsk controller, and it's no longer possible to do this from software—which is a good thing, if you ask me.

It should be noted that the error you are seeing occurs while reading (not writing) the data. The fact that the data can be re-read means that it's probably stored on the magnetic media OK and that the problem is in the transportation of the data, not its storage. Detecting bad sectors on write, sparing those sectors, and writing the data to a more reliable region of the drive is the job of the hard disk controller. If it's not doing that, then you need a new drive/controller.