Am 2016-08-17 11:12, schrieb Roger Pau Monné:

No, I don't think so, this is what I get using a slow USB 2.0 disk as the
backend: (on Dom0 I get something between 70-80M/s, so there isn't much

# dc3dd wipe=/dev/ada1

dc3dd 7.2.641 started at 2016-08-17 09:03:26 +0000
compiled options:
command line: dc3dd wipe=/dev/ada1
device size: 2097152 sectors (probed),    1,073,741,824 bytes
sector size: 512 bytes (probed)
  1073741824 bytes ( 1 G ) copied ( 100% ),   16 s, 65 M/s

input results for pattern `00':
   2097152 sectors in

output results for device `/dev/ada1':
   2097152 sectors out

dc3dd completed at 2016-08-17 09:03:42 +0000

What may I be doing wrong?

TBH it's hard to tell, I don't know of any option that could cause this disk performance degradation. Do you also have ada* devices apart from the xbd* ones? I don't think it's going to make any difference, but could you try
with the ada* block devices instead?

Strange thing is, I have ada devices for the the other disks, but this one didn't show up as ada-device.

On my FreeBSD11 Test VM, the disk didn't show up until I rebooted, even though I (believe to) have the xen-guest stuff installed:

(freebsd11 </root>) 0 # ps ax |grep xe-d
694 v0- I 0:00.00 /bin/sh /usr/local/sbin/xe-daemon -p /var/run/
2202  0  R+   0:00.00 grep xe-d
(freebsd11 </root>) 0 # pkg info|grep xe-
xe-guest-utilities-6.2.0_2 FreeBSD VM tools for Citrix XenServer and XCP
(freebsd11 </root>) 0 # pkg info|grep xen
xen-guest-tools-4.6.1          Xen tools within FreeBSD domU

I have an ada device there and I got about 10MB/s on wipe. At least in the beginning.

(freebsd11 </root>) 0 # sysctl -a |grep xen
kern.vm_guest: xen
device  xenpci
vfs.pfs.vncache.maxentries: 0
dev.xenbusb_back.0.%parent: xenstore0
dev.xenbusb_back.0.%driver: xenbusb_back
dev.xenbusb_back.0.%desc: Xen Backend Devices
dev.xn.0.xenstore_peer_path: /local/domain/0/backend/vif/245/0
dev.xn.0.xenbus_peer_domid: 0
dev.xn.0.xenbus_connection_state: Connected
dev.xn.0.xenbus_dev_type: vif
dev.xn.0.xenstore_path: device/vif/0
dev.xn.0.%parent: xenbusb_front0
dev.xbd.1.xenstore_peer_path: /local/domain/0/backend/vbd3/245/768
dev.xbd.1.xenbus_peer_domid: 0
dev.xbd.1.xenbus_connection_state: Connected
dev.xbd.1.xenbus_dev_type: vbd
dev.xbd.1.xenstore_path: device/vbd/768
dev.xbd.1.%parent: xenbusb_front0
dev.xbd.0.xenstore_peer_path: /local/domain/0/backend/vbd3/245/832
dev.xbd.0.xenbus_peer_domid: 0
dev.xbd.0.xenbus_connection_state: Connected
dev.xbd.0.xenbus_dev_type: vbd
dev.xbd.0.xenstore_path: device/vbd/832
dev.xbd.0.%parent: xenbusb_front0
dev.xenbusb_front.0.%parent: xenstore0
dev.xenbusb_front.0.%driver: xenbusb_front
dev.xenbusb_front.0.%desc: Xen Frontend Devices
dev.xs_dev.0.%parent: xenstore0
dev.xctrl.0.%parent: xenstore0
dev.xenballoon.0.%parent: xenstore0
dev.xenballoon.0.%driver: xenballoon
dev.xenballoon.0.%desc: Xen Balloon Device
dev.debug.0.%parent: xenpv0
dev.privcmd.0.%parent: xenpv0
dev.evtchn.0.%parent: xenpv0
dev.xenstore.0.%parent: xenpv0
dev.xenstore.0.%driver: xenstore
dev.xenstore.0.%desc: XenStore
dev.xen_et.0.%parent: xenpv0
dev.xen_et.0.%driver: xen_et
dev.xen_et.0.%desc: Xen PV Clock
dev.granttable.0.%parent: xenpv0
dev.xenpv.0.%parent: nexus0
dev.xenpv.0.%driver: xenpv
dev.xenpv.0.%desc: Xen PV bus
dev.xenpci.0.%parent: pci0
dev.xenpci.0.%pnpinfo: vendor=0x5853 device=0x0001 subvendor=0x5853 subdevice=0x0001 class=0x010000 dev.xenpci.0.%location: slot=3 function=0 dbsf=pci0:0:3:0 handle=\_SB_.PCI0.S18_
dev.xenpci.0.%driver: xenpci
dev.xenpci.0.%desc: Xen Platform Device
dev.xen.xsd_kva: 18446735281894703104
dev.xen.xsd_port: 3
dev.xen.balloon.high_mem: 0
dev.xen.balloon.low_mem: 0
dev.xen.balloon.hard_limit: 18446744073709551615
dev.xen.balloon.driver_pages: 0 2097152
dev.xen.balloon.current: 2096128

Do you know what I could check on the dom0 side to make sure it's configured right?

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