Subject: Re: Funny -> ATA drive read error
To: Manuel Bouyer <>
From: Markus W Kilbinger <>
List: netbsd-users
Date: 06/04/2004 10:08:05
>>>>> "Manuel" == Manuel Bouyer <> writes:

    >> On Thu, Jun 03, 2004 at 09:00:22PM +0800, Todd Gruhn wrote:
    >> Jun  3 08:17:01 gandalf /netbsd: wd0: (uncorrectable data error)
    >> Jun  3 08:17:01 gandalf /netbsd: wd0: transfer error, downgrading to Ultra-DMA mode 1
    >> Jun  3 08:17:01 gandalf /netbsd: wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 1 (using DMA data transf
    >> ers)
    >> Jun  3 08:17:01 gandalf /netbsd: wd0e: error reading fsbn 3034368 of 3034368-3034383 (wd0 bn 4193568; cn 416
    >> 0 tn 4 sn 36), retrying

    Manuel> This is specific to ATA drives. "uncorrectable data error"
    Manuel> is one of the few error conditions an ATA drive can
    Manuel> report. This error mean that your drive has a bad block.

I had the same problem with one of our ata drives last days...

    Manuel> You can try to write to this block to try to remap it.

... and could really fix it with such a write attempt! :-)

Strange thing: After the read error occured once no further access
(read and write) to the erroneous block (and afterwards) is possible
on a running system, further I only see Input/Output error's for these

So I had to reboot the machine to get the erroneous block accessible
again. ... and then I have to do the write attempt first to fix the


Is it normal that once as erroneous detected blocks are permanently
marked/remembered as failed? (Is this a feature of the disk or of the
driver? Any {ata,dk}ctl command to change this behavior?)