Rebuild speeds and recently failed devices oops

Andrew,

I had set the min to 15000 (15MB/s) and max to 80000 (80MB/s). My
rebuild rate still wouldn't go above 7MB/s. :(

Sean.

> I was seeing similar rebuild performance on my large number of RAID1
> arrays (the first rebuilds went speedy and subsequent ones slowed down
> after the first ones completed).  I bumped up the speed_limit_min and
> the rebuild performance went up to where I expected it to be. 
> 
> What were you speed_limit_[min|max]?
> 
> -----Original Message-----
> From: Sean Kormilo [mailto:skormilo@xxxxxxxxxxxxxxxxxx] 
> Sent: Thursday, March 13, 2003 8:48 AM
> To: Neil Brown
> Cc: linux-raid@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] md - 1 of 12 - Missing mddev_put in md resync code
> 
> 
> Neil,
> 
> > 
> > No.  There have been lots of changes since 2.4.  Some patches might 
> > conceptually apply, but they would need a bit of work to make them 
> > actually apply.
> 
> Ok, then I won't give it a try. Thanks for the heads up.
> > 
> > > 
> > > It looks like one or more of these might reduce the chances of the 
> > > kernel oops I experience on occasion when manipulating arrays.
> > 
> > Would this be when removing a recently-failed device?  That can still 
> > oops.  I should send in a patch for that...
> 
> Yes in fact, that is the one I was seeing.
> 
> 
> > These patches are about management, not performance.  They won't 
> > affect rebuild performance at all.  It is already quite good in 2.4 I 
> > believe.  But maybe my experience is different from your.
> 
> I have an odd problem where the first rebuild performs as expected
> (about 40MB/s), but any subsequent rebuild plods along at about 6-7MB/s.
> There is no IO activity on the system other than the rebuild during my
> tests.
> 
> I tried putting in a couple of debug printk's here and there in the code
> that backs off the resync, and the printk's themselves returned the
> performance back to expected levels... some kind of a timing problem
> perhaps?
> 
> Sean.
-- 

Sean C. Kormilo, STORM Software Architect, Nortel Networks
              email: skormilo@xxxxxxxxxxxxxxxxxx
  

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