Harddisk "UDMA ICRC error..." from kernel at bootup. What does it mean?

[Bill Moran]

Rob <stopspam at users.sourceforge.net> wrote:
> Hi,
> 
> A friend of mine switched from Windows XP to FreeBSD, because I "garanteed" that FreeBSD
> would be faster. I also want to optimize performance as much as possible. I'm therefore
> worried about the following messages from the kernel at bootup:
> 
> [...snip...]
> ad0: 16448MB <WDC WD172AA> [33420/16/63] at ata0-master UDMA66
> ad1: 76319MB <WDC WD800JB-00CRA1> [155061/16/63] at ata0-slave UDMA66
> acd0: CD-RW <HL-DT-ST RW/DVD GCC-4320B> at ata1-master PIO4
> Mounting root from ufs:/dev/ad0s1a
> ad1s5c: UDMA ICRC error reading fsbn 93787664 of 46885768-46885895 (ad1s5 bn 93787664; cn 5838 tn 3 sn 5) retrying
> ad1s5c: UDMA ICRC error reading fsbn 93787664 of 46885768-46885895 (ad1s5 bn 93787664; cn 5838 tn 3 sn 5) retrying
> ad1s5c: UDMA ICRC error reading fsbn 93787664 of 46885768-46885895 (ad1s5 bn 93787664; cn 5838 tn 3 sn 5) retrying
> ad1s5c: UDMA ICRC error reading fsbn 93787664 of 46885768-46885895 (ad1s5 bn 93787664; cn 5838 tn 3 sn 5) falling back to PIO mode
> 
> ---
> 
> Both harddisks are on the same IDE 40-pin cable as master and slave.
> ad0 is the FreeBSD formatted harddisk; one slice and several FreeBSD partitions.
> ad1 is from a former Windows XP installation, with two partitions: ad1s5 (ntfs) and ad1s6 (msdos).
> 
> I don't understand much of the lines above.

Super-simplified: it's telling you it gets checksum erros when it tries to
talk to the drives at ATA66 speed, so it slows down and is then successful.

> The last line says it falls back to PIO mode due to errors with ad1s5c.
> What does that mean? Will it use the slow 16.6 MB/s data exchange from disk to host?

Yes.  Windows is probably already running at this speed, but it just doesn't
bother to inform you.

> Does this then also imply that both disks use PIO/slow data exchange speed?
> (remember: both disks are on the same cable to the motherboard).

Yes.

> What can I do to get things better and faster?

Get an 80 conductor cable (probably).

> And also: is this "UDMA ICRC error" because it's a Windows/DOS partition?
> Would formatting to FreeBSD filesystem solve the problem?

No, it's more likely because of the 40 pin cable.

-- 
Bill Moran
Potential Technologies
http://www.potentialtech.com