I am using kpartx to mount some VMware vmdk virtual disks in order to write some data to the partitions contained therein. Initially writing the data starts off fine, but within about 30 seconds or after a few hundred megabytes is written, everything grinds to a halt and IO plummets. When mounting the vmdk partitions using losesetup, performance is better and doesn't stop but it does appear to slow down at times. The vmdk's are located on a USB3 disk and the disk performance is good when writing to the disk itself. I am copying one of the vmdk's to a local disk on the server to see if the USB disk is a factor and will advise. When I monitor it using "atop" I can see high utilisation that seems to swap between the physical disk and the loop device being written to. I am using Debian Wheezy with Kernel 3.2.0-4-amd64 and kpartx 0.4.9+git0.4dfdaf2b-6 Is this is a known limitation or something that kpartx was never intended to support... or perhaps a bug? Kind Regards, James -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel