On Mon, 30 Jun 2014 16:23:45 -0400
Lamar Owen <[log in to unmask]> wrote:

> On 06/30/2014 03:52 PM, Andras Horvath wrote:
> > Actually the drive has its own power so it is not USB powered. I 
> > cannot tell if the drive spins down (did not get the idea to check 
> > it), but the CPU is in 100% I/O wait all the time after this happens. 
> > I was told the disk is a WD RED, but I'll check the power mode later 
> > with hdparm.
> 
> The only time I've personally run into the 100% I/O wait issue with EL6 
> was when I was trying to RAID a Seagate 1.5TB internal SATA drive with a 
> WD GREEN 1.5TB SATA drive.  The system was basically unusable, with 
> frequent and long forays into 100% iowait territory. Replacing the WD 
> GREEN drive with another 1.5TB Seagate fixed that. It could be WD's 
> TLER/non-TLER (Time-Limited Error Recovery) handling doing this.  More 
> info on this at http://www.wdc.com/en/library/other/2579-001098.pdf and 
> googling 'WD TLER' yields a lot of hits.
> 
> Another possibility is that the idle timer is set up on the disk; I 
> would think that it would hit you sooner, though, if it was that issue.  
> I ran into that sort of issue with an eSATA Seagate a long time ago, 
> where throughput was good but after a while it would error out.  For 
> some reason the standard Linux write caching and the timeout interacted 
> badly.  There's more about the WD RED and GREEN drives and this idle 
> timer at 
> http://forums.freenas.org/index.php?threads/hacking-wd-greens-and-reds-with-wdidle3-exe.18171/ 
> with some open source tool at http://idle3-tools.sourceforge.net/

It would make sense, but I tried every part with different new hardware. I still cannot access my machine because it still could not reboot from the high I/O so I'll check the spin down setting tomorrow in the morning.

Also, this very thing happened on a production server with many services and on my single backup machine too that has no services at all except a single SSHd without RAID. So we can say this error comes up on a basic install of SL 6 with different kinds of my hardware where the system works normal without the USB drive.

You mentioned eSATA, I might go look into setting that one up instead of USB.