Dying disk or missing quirk?

[Henrik Brix Andersen]

I recently acquired a Revoltec Alu Book USB mass storage enclosure for
a 2.5" PATA HDD, which is based on the Myson CE8818 chipset and
therefore matched by the (wrongly named, as this matches all CE8818
based devices) following USB quirk in -current:

        { USB_VENDOR_MYSON,  USB_PRODUCT_MYSON_HEDEN, RID_WILDCARD,
          UMASS_PROTO_SCSI | UMASS_PROTO_BBB,
          NO_INQUIRY | IGNORE_RESIDUE
        },

The enclosure works fine under low disk I/O, but under heavy disk
activity, I get the following:

kernel: umass0: <Myson Century, Inc. USB Mass Storage Device, class 0/0, rev 2.00/b0.08, addr 2> on uhub4
root: Unknown USB device: vendor 0x04cf product 0x8818 bus uhub4
kernel: da0 at umass-sim0 bus 0 target 0 lun 0
kernel: da0: <  > Removable Direct Access SCSI-2 device 
kernel: da0: 40.000MB/s transfers
kernel: da0: 114473MB (234441648 512 byte sectors: 255H 63S/T 14593C)
...
kernel: (da0:umass-sim0:0:0:0): READ(10). CDB: 28 0 8 45 78 6f 0 0 48 0 
kernel: (da0:umass-sim0:0:0:0): CAM Status: SCSI Status Error
kernel: (da0:umass-sim0:0:0:0): SCSI Status: Check Condition
kernel: (da0:umass-sim0:0:0:0): ILLEGAL REQUEST asc:20,0
kernel: (da0:umass-sim0:0:0:0): Invalid command operation code
kernel: (da0:umass-sim0:0:0:0): Unretryable error
kernel: g_vfs_done():da0s1a[READ(offset=71050477568, length=36864)]error = 22
kernel: vnode_pager_getpages: I/O read error
kernel: vm_fault: pager read error, pid 27989 (cp)

cp(1) says the following, and the destination file is corrupt:
cp: /foo/bar/baz.txt: Bad address

Question is, what is causing this? A dying disk? A quirky chipset? or
something else?

Brix
-- 
Henrik Brix Andersen <brix at FreeBSD.org>
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