On 4/12/12, Stan Hoeppner stan@hardwarefreak.com wrote:
On 4/11/2012 11:50 AM, Ed W wrote:
One of the snags of md RAID1 vs RAID6 is the lack of checksumming in the event of bad blocks. (I'm not sure what actually happens when md scrubbing finds a bad sector with raid1..?). For low performance requirements I have become paranoid and been using RAID6 vs RAID10, filesystems with sector checksums seem attractive...
Except we're using hardware RAID1 here and mdraid linear. Thus the controller takes care of sector integrity. RAID6 yields nothing over RAID10, except lower performance, and more usable space if more than 4 drives are used.
How would the control ensure sector integrity unless it is writing additional checksum information to disk? I thought only a few filesystems like ZFS does the sector checksum to detect if any data corruption occurred. I suppose the controller could throw an error if the two drives returned data that didn't agree with each other but it wouldn't know which is the accurate copy but that wouldn't protect the integrity of the data, at least not directly without additional human intervention I would think.