I have a software RAID10 array (4-1TB drives) that I have assembled in a kvm vm on Proxmox (Debian Squeeze 6.0). The HDDs were mapped to the vm using virtio. The array once created and started in the vm (during resync) started throwing an I/O error on one of the disks. It kept repeating the error until I stopped the array. At the host level I ran smartctl on all drives and they all passed inspection. The drives are not all the same brand. The array is made up of 1 Seagate Barracuda, 2 WD Blacks, and 1 Hitachi. The Seagate is an Advanced Format with sector size (logical/physical) equal to 512B/4096B. The other drives are standard format 512B/512B. All drives are configured as GPT and have been partioned (using parted) to be aligned as follows: Number Start End Size File system Name Flags 1 1049kB 1000GB 1000GB udata_raid2 raid Is it possible that the physical sector size of 4096B of the Seagate drive is causing the problem? I don't believe that the I/O error was on the Seagate (I can't recall which it was on at the time). The HDD's where mapped to virtio devices using the following: qm virtio# /dev/disk/by-id/ata- Any thoughts? -- James