On Thu, Dec 10, 2009 at 6:00 PM, Marco Peereboom <sl...@peereboom.us> wrote: >> Does this mean there's little advantage of hardware mirror raid over software? >> So software mirror raid increases chances of data corruption while decreasing >> the chances of downtime. True for hardware as well? > > There are pro and cons to both solutions. Pick what makes sense in your > scenario. > >> Hmmm. I've used hardware raid cards for mirrors that have the verify function. >> It would be interesting to know how and what those cards do. > > They read the data to make sure the disk is working. If one disk is > failed they can rebuild that block from the remaining disk provided that > the remaining disk isn't corrupt or broken too. They assume that the > data that was read is accurate; if it isn't you are SOL. > > They either don't detect or ignore blocks that are different because > they can not know which one is accurate (if any). > > Verify for RAID 1 is mostly marketing fluff.
Thanks a lot for this info. In the past I've had weird corruption of files with a raid card - some files on the volume would become corrupt, but the corruption was limited to files only. IOW the whole volume would be intact and I could write and read new files to it but as the time went some individual files would contain garbage instead of real data. I wonder what that was all about.
