Greetings,

I have built many RAID systems using desktop disks and they are
generally quite stable. One of the issues with WD drives are with their
Green drives. By default, they park the heads after ~8 seconds of
inactivity. This will cause them to drop out of the array. The disk
firmware can be configured to disable this feature. I have had very good
luck with Samsung and Seagate drives. I have never spent the money on
Enterprise level drives.

BTW: The head parking feature is notoriously bad. If you calculate 1
park every 8 seconds. At constant usage, the drive will die in about 3
months. Perhaps this feature is fine for a desktop, but it is not for a
server or production environment.

	Good luck,
	doug


> 
> My understanding is that the main difference between desktop drives
> and enterprise raid array drives in this regard is that the drive firmware
> is configured to retry errors a lot longer on the desktop drives.
> It is also my experience, although it was a few years ago on older
> model WD drives, that the main thing that would produce problems of
> disk drives dropping out of the array (desktop or enterprise)
> is unexpected vibration of one kind or another.  Easy for harmonics
> to build up between the fans and the drive heads.
> We have several Megaraid 9260-i controllers (and their successors and 
> their predecessors) in production but we did spend the money for the 
> enterprise drives.
> 
> Steve Timm
> 
> 
> On Thu, 4 Oct 2012, Ken Teh wrote:
> 
> > I've run into problems trying to use desktop disks in a RAID array with a 
> > MegaRAID 9260-8i.  I built 2 previous systems with desktop disks and did not 
> > have any problems but I've been unable to get this 3rd system to function 
> > stably.  Disks dropped from the array except the disks are fine which I 
> > proved by deleting the disk group and starting again.
> >
> > This behaviour is consistent with Western Digital's discussion about TLER 
> > (time-limited error recovery) and their admonition to use enterprise disks 
> > instead of desktop disks.
> >
> > I was wondering if there are ways of getting around this problem without 
> > having to buy another set of disks.  Googling suggests some options to try 
> > but I thought I'd used the list as a sounding board first before embarking on 
> > options.
> >
> > Thanks!
> >
> 
> ------------------------------------------------------------------
> Steven C. Timm, Ph.D  (630) 840-8525
> [log in to unmask]  http://home.fnal.gov/~timm/
> Fermilab Computing Division, Scientific Computing Facilities,
> Grid Facilities Department, FermiGrid Services Group, Group Leader.
> Lead of FermiCloud project.
> 

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   Doug Johnson                    email: [log in to unmask]        
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