see freebsd-usb@ on 17. Oct 2015 External USB Harddisk ZFS boot problem, the problem disapeared after adding the quirk.

Thx @HPS for the hint.


[root@nas01 /usr/src]# svn diff sys/dev/usb/quirk/usb_quirk.c 
Index: sys/dev/usb/quirk/usb_quirk.c
===================================================================
--- sys/dev/usb/quirk/usb_quirk.c	(revision 290054)
+++ sys/dev/usb/quirk/usb_quirk.c	(working copy)
@@ -333,6 +333,7 @@
 	USB_QUIRK_VP(USB_VENDOR_SAMSUNG_TECHWIN,
 	    USB_PRODUCT_SAMSUNG_TECHWIN_DIGIMAX_410, UQ_MSC_FORCE_WIRE_BBB,
 	    UQ_MSC_FORCE_PROTO_SCSI, UQ_MSC_NO_INQUIRY),
+	USB_QUIRK(SAMSUNG, M3_PORTABLE, 0x0000, 0xffff, UQ_MSC_NO_SYNC_CACHE),
 	USB_QUIRK(SANDISK, SDDR05A, 0x0000, 0xffff, UQ_MSC_FORCE_WIRE_CBI,
 	    UQ_MSC_FORCE_PROTO_SCSI, UQ_MSC_READ_CAP_OFFBY1,
 	    UQ_MSC_NO_GETMAXLUN),
[root@nas01 /usr/src]# svn diff sys/dev/usb/usbdevs
Index: sys/dev/usb/usbdevs
===================================================================
--- sys/dev/usb/usbdevs	(revision 290054)
+++ sys/dev/usb/usbdevs	(working copy)
@@ -3812,6 +3812,7 @@
 product SAMSUNG I500		0x6601	I500 Palm USB Phone
 product SAMSUNG I330		0x8001	I330 phone cradle
 product SAMSUNG2 RT2870_1	0x2018	RT2870
+product SAMSUNG M3_PORTABLE	0x61b7	M3 Portable Samsung



# usbconfig -u 0 -a 4 dump_device_desc
ugen0.4: <M3 Portable Samsung> at usbus0, cfg=0 md=HOST spd=SUPER (5.0Gbps) pwr=ON (36mA)

  bLength = 0x0012 
  bDescriptorType = 0x0001 
  bcdUSB = 0x0300 
  bDeviceClass = 0x0000  <Probed by interface class>
  bDeviceSubClass = 0x0000 
  bDeviceProtocol = 0x0000 
  bMaxPacketSize0 = 0x0009 
  idVendor = 0x04e8 
  idProduct = 0x61b7 
  bcdDevice = 0x0000 
  iManufacturer = 0x0002  <Samsung>
  iProduct = 0x0003  <M3 Portable>
  iSerialNumber = 0x0001  <NA820YR2>
  bNumConfigurations = 0x0001