Re: "raid5:md0: read error not correctable (sector 795463080 on sdf1)" error on controller with SIL 3114

[Robert Hancock <hancockrwd@gmail.com>]

On 02/08/2010 05:11 AM, Håkon Løvdal wrote:
> Hi. I have had some trouble with the machine I want to have as a file server.
>
> After having let the "get raid up and running reliably" project lie
> dormant for some time, I tried again this Friday. After connecting the
> disks, the status was the following: 4 out of 6 disk in a raid6 setup
> were recognised (see log-1). I was able to mount the volume when the
> machine was finished booting.
>
> I then added the two missing disks with mdadm, one of them started
> rebuilding and the other one were not recognised in some way (log-2).
> The rebuild of the disk was successfull (log-3), but later some errors
> occured, see log-4 below, and now only three disks are left in the
> array (log-5).
>
> Are these errors related to Tejun's recent statement "Sil3112/3114 are
> now virtually the only controllers with occassional and unresolved data
> corruption issues."? Disks sda (hosting root file system for os), sdb
> sdc and sdd are connected the motherboard while sde, sdf and sdg are
> connected to a controller card using 3114:

..

> ---BEGIN log-4---
> Feb  6 07:09:57 localhost kernel: ata8.00: exception Emask 0x0 SAct
> 0x0 SErr 0x0 action 0x0
> Feb  6 07:09:57 localhost kernel: ata8.00: BMDMA2 stat 0x6c0009
> Feb  6 07:09:57 localhost kernel: ata8.00: cmd
> 25/00:80:cf:cd:69/00:00:2f:00:00/e0 tag 0 dma 65536 in
> Feb  6 07:09:57 localhost kernel:         res
> 51/40:00:e4:cd:69/00:00:2f:00:00/e0 Emask 0x9 (media error)
> Feb  6 07:09:57 localhost kernel: ata8.00: status: { DRDY ERR }
> Feb  6 07:09:57 localhost kernel: ata8.00: error: { UNC }

That's fairly definitive, uncorrected read error reported by the drive. 
You might want to check its SMART status. Could be a bad drive, or 
potentially other causes like excessive vibration, high temperature, 
power issues..