Re: questions about io scheduler

[Mike Fedyk]

Timothy Miller wrote:
> Mike Fedyk wrote:
>
> > Nick Piggin wrote:
> >
> > > Kyle Wong wrote:
> > >
> > > > 2. Does io scheduler works with md RAID? Correct me if I'm wrong,
> > > > io-schedular <-->  md driver <--> harddisks.
> > >
> > > It goes md driver -> io schedulers -> hard disks.
> >
> >
> >
> > There is an IO scheduler per disk.
> >
> > So MD submits the data to each disk through the IO scheduler.
> >
> > This allows you to have the heads on each disk in the array at 
> > different locations, and helps keep response times lower for seeky loads.
>
>
> Say you've got a RAID1.  In this case, MD could send the read request to 
> either device.  How does it decide which one to use?

The one with the drive head closest to the data.
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