I suspect two things: RAM and one of your disk controllers. Going for the latter first---when you created non-LVM tests, were you using the same disk? Probably not. Same IDE or SATA channels? Maybe you only get random errors from one of your IDE channels, or only one of your SATA channels, or perhaps everything that passes through the Northbridge, or something like that. You may have to swap disks around to do fault isolation. The fact that the errors -stick- once the data's in RAM makes me think that it's getting trashed on the way in but that otherwise your RAM might be good. But maybe it's not. I had a bizarre failure once where I thought I had a network problem, since I detected it when dd'ing 500GB from one machine to another. Turns out the problem was bad behavior in my RAM, but ONLY WHEN when the CPU was throttled down! Once I turned off CPU throttling, the random errors went away. And, of course, memtest86+ never saw it, because it -always- nails the CPU... (In my case, I saw bit flips via md5sum whether the data was coming from IDE, SATA, or even a USB stick---and there's very little hardware in common there. A tight loop md5summing the same file (one which fit in RAM) got wrong, wrong, right right right right and the "rights" suddenly started getting spit out much faster---it was at that moment that I realized the wrong values were probably being produced while the CPU was throttled. [And putting a 10-second sleep in between each md5sum got mostly wrong values---but as soon as I started nailing the CPU in another process, the values being spit out by the loop, even with the pauses, became correct...]. The dd didn't use enough CPU time to throttle up, so I saw errors---and at about the same rate as you, maybe one bit flip every few gig. And I -knew- the data coming in from the disks -had- to be good because it was a crypto filesystem ---bit errors there would trash entire blocks, and that wasn't happening.) _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
