On Wed, 2 May 2012, Norman Diamond wrote: > Alan Stern wrote: > > On Tue, 1 May 2012, Norman Diamond wrote: > >> When a 3TB SATA drive is connected through a JMicron JMS539 (USB3.0 > >> to SATA Bridge, 152d:0539), Windows sees 3TB and Linux sees 3TB. > >> > >> When the same drive is connected through a JMicron 20337 (152d:2338), > >> Windows sees 3TB but Linux sees 800GB.� (Fortunately Linux avoids > >> mounting the truncated partitions.) > > > > For debugging issues like this, usbmon is your friend. > > OK, quoted below is usbmon for donnection and disconnection through > the JMicron 20337. > > Do you also need usbmon for the JMicron JMS539 which is handled properly? No. > Meanwhile I tested my Prolific bridge again too, with an additional > PATA-to-SATA adapter. Windows sees 3TB but Linux sees 800GB minus > one block. Do you need usbmon for that? Probably the two bridges have the same bug. > usbmon for the JMicron 20337 is around 2000 lines, which seemed like > enough for one mail message. Here's the interesting part: > edb17580 3641398166 S Bo:2:003:2 -115 31 = 55534243 03000000 08000000 80000a25 00000000 00000000 00000000 000000 > edb17580 3641398233 C Bo:2:003:2 0 31 > > edb17c80 3641398246 S Bi:2:003:1 -115 8 < > edb17c80 3641398357 C Bi:2:003:1 0 8 = 5d50a3af 00000200 > edb17580 3641398444 S Bi:2:003:1 -115 13 < > edb17580 3641398608 C Bi:2:003:1 0 13 = 55534253 03000000 00000000 00 This shows a READ CAPACITY command. The response says the highest numbered LBA is 1565565871 (5d50a3af in hex) and each block is 512 bytes. That amounts to a little over 800 GB, which is what you saw. It looks like the bridge is sending just the least-significant 32 bits of the capacity. What it should have done is reply with 0xffffffff. Then the kernel would know to try again with a READ CAPACITY(16) command, which is capable of retrieving values larger than 32 bits. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
