From: Alan Stern Subject: Re: Weird I/O errors with USB hard drive not remounting filesystem readonly Date: Tue, 24 Nov 2009 12:16:17 -0500 (EST) Message-ID: References: <20091123234234.GA22126@roll> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Jan Kara , , , Jens Axboe , , To: tmhikaru@gmail.com Return-path: In-Reply-To: <20091123234234.GA22126@roll> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, 23 Nov 2009 tmhikaru@gmail.com wrote: > Thank you. I've gotten output of it screwing up, but it's a 62MB file. I > don't think I'm allowed to send attachments here, nor do I know what I'm > supposed to be looking for in this output. So, instead I'm putting the > (compressed) file up on my home computer. If you've got suggestions for what > I should use instead, let me know. > > http://hikaru.no-ip.info:3000/1.mon.out.xz > > Although I don't think you'll need it, I've included the dmesg output of > what happened when I ran my backup script, just in case it helps at all. Here's an annotated example of one of those hiccups: f1aa1f00 2416018820 S Bo:1:003:1 -115 31 = 55534243 07050100 00100000 80000a28 000000ae ef000008 00000000 000000 f1aa1f00 2416018929 C Bo:1:003:1 0 31 > The computer issued a READ command for 8 blocks (4096 bytes) starting at block number 0x0000aeef = 44783. d2588b00 2416019342 S Bi:1:003:2 -115 4096 < d2588b00 2416019428 C Bi:1:003:2 -32 0 f1aa1f00 2416019435 S Co:1:003:0 s 02 01 0000 0082 0000 0 f1aa1f00 2416019554 C Co:1:003:0 0 0 The drive returned 0 bytes of data. f1aa1f00 2416019560 S Bi:1:003:2 -115 13 < f1aa1f00 2416019678 C Bi:1:003:2 0 13 = 55534253 07050100 00100000 00 And then it returned a status indicating no error but 4096 bytes residue (i.e., incorrect or undelivered data). This caused the usb-storage driver to send the SCSI layer a result code of DID_ERROR with no sense data. > sd 0:0:0:0: [sda] Unhandled error code > sd 0:0:0:0: [sda] Result: hostbyte=0x07 driverbyte=0x00 > end_request: I/O error, dev sda, sector 44783 The DID_ERROR code caused the SCSI layer to display this error message. > sd 0:0:0:0: [sda] Unhandled error code > sd 0:0:0:0: [sda] Result: hostbyte=0x07 driverbyte=0x00 > end_request: I/O error, dev sda, sector 51823 I would have expected the READ to be retried, but in these two cases it wasn't. The usbmon log contained five instances of this error sequence; the other three were retried successfully. I don't know what the difference was. Alan Stern