0) what is the full DD command you are issuing? (I think we have this) 1) does your DD command work when LVM is not using caching of any kind.
2) does your DD command work if using 'direct' mode 3) are you able to write smaller chunks from NON-cached LVM volume to SSD vdev? Is there an inflection point in size where it goes haywire? 4) what is your IO elevator/scheduler set to? 5) what is value of vm.dirty_background_ratio vm.dirty_ratio vm.dirty_background_bytes vm.dirty_bytes What do you observe in /proc/vmstat during DD? 6) run DD via strace _______________________________________________ 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/
