Redundancy

James

Please can you clarify the value, or otherwise of using QRecall's redundancy feature if the archive is stored in a RAID 5 array or a ZFS Mirror.

Thanks
Adrian

Adrian Chapman wrote:Please can you clarify the value, or otherwise of using QRecall's redundancy feature if the archive is stored in a RAID 5 array or a ZFS Mirror.

There are no advantages. If you are using a filesystem or device that performs error correction, your archive's data redundancy should be set to "none".

QRecall's data redundancy in inferior to both hardware (RAID5) and filesystem-level (ZFS) error correction. It cannot protect against whole-device failures (like RAID5) and it cannot evenly distribute correction codes across the media (as ZFS can). (QRecall "encourages" the filesystem to distribute the correction blocks, but since applications have no control over how a filesystem organizes blocks, this can't be guaranteed.)

QRecall's error correction is intended for use on simple hard drives that lack any kind of error detection or correction.

Thanks James, I thought you might say something like that but I thought it best to check.

Adrian