Re: time limited error recovery and md raid

[Redeeman <redeeman@metanurb.dk>]

On Fri, 2008-12-05 at 18:52 -0500, Justin Piszcz wrote:
> 
> On Sat, 6 Dec 2008, Redeeman wrote:
> 
> > On Fri, 2008-12-05 at 16:01 -0500, Justin Piszcz wrote:
> >>
> >> On Fri, 5 Dec 2008, Redeeman wrote:
> >>
> >>> Hello..
> >>>
> >>> Im going to be building a software raid6 setup with probably 8 disks,
> >>> and i've been looking at the wd gp disks, which comes in both standard
> >>> and raid edition, with the raid edition being much more expensive.
> >>>
> >>> I have searched around, and found that it is indeed possible to activate
> >>> tler on the "normal" disks, however, the setting has a parameter, more
> >>> specifically, how many seconds it should be limited to. Default is 7.
> >>>
> >>> So i was wondering, what should that be set to, to be optimal for linux
> >>> md raid? i havent been able to find any information about this.
> >>>
> >>>
> >>> Thanks.
> >>>
> >>>
> >>> mvh.
> >>> Kasper Sandberg
> >>>
> >>> --
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> >>>
> >>
> >> The exact time is a good question.
> >
> > About this, shouldnt it be possible to find the exact time which the
> > linux raid system waits until it auto kicks out the drive?
> >
> >
> >>
> >> Something I have noticed is when TLER is off, the drives hang up when they
> >> hit a bad sector and when TLER is on, the drives is kicked out of the
> >> array immediately when it reports a bad sector.
> >
> > On further thought, might this not suggest that the linux raid system
> > waits indefinetly for I/O error, before kicking out?
> It times out after 1-2 minutes.  I have been dealing with this for a very long
> time, another 'symptom' is short smart tests taking forever when the disk is in 
> a soon-to-be failing state.

Do you know if this is actually caused by the disk's error recovery
timing out in 1-2 minutes, or the linux raid system?

> >
> > If that is indeed the case, then if the use of the raid isnt
> > time-critical, then maybe its a good thing to have tler enabled, just in
> > case the disk is able to fix stuff?
> With TLER enabled the drive is kicked out immediately. The purpose of TLER is
> that of HW raid where it can alert the controller about it and the controller
> handles it.
> 
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