On Sun, Sep 21, 2008 at 10:26 AM, Nataraj <incoming-centos at rjl.com> wrote: > Does software raid 1 compare checksums or otherwise verify that the same > bits are coming from both disks during reads? What I'm interested in, No. Reads are distributed over disks to increase performance. > is whether bit errors that were somehow undetected by the hardware would > be detected by the raid 1 software. Depends on the type of error. However, the sad thing is, if you use 3 disks for raid 1 the kernel does not do the right thing. Let me explain. Say you have 3 disks in a raid 1 array. If there is a mismatch then the smart thing to do would be to take a vote of the 3 disks. 2 out of 3 wins (assuming they are not all different). The odd man out should be corrected (if possible). But what actually happens is the highest numbered disk is copied to the others. I haven't looked at the latest kernel code but if this http://linas.org/linux/raid.html is correct then I think the kernel maintainers should address this issue. I don't think it would be hard to implement. -- Robert Arkiletian Eric Hamber Secondary, Vancouver, Canada Fl_TeacherTool http://www3.telus.net/public/robark/Fl_TeacherTool/ C++ GUI tutorial http://www3.telus.net/public/robark/