Re: how to clone a disk

[Ming Zhang <mingz@ele.uri.edu>]

On Sat, 2006-03-11 at 06:53 -0500, Paul M. wrote:
> Since its raid5 you would be fine just pulling the disk out and
> letting the raid driver rebuild the array. If you have a hot spare

yes, rebuilding is the simplest way. but rebuild will need to read all
other disks and write to the new disk. when serving some io at same
time, the rebuilding speed is not much,

but if i do a dd clone and plug it back. the total traffic is copy one
disk which can be done very fast as a fully sequential workload. with
that bitmap feature, the rsync work after plugging back is minor.

so the one disk fail window is pretty small here. right?

ming



> then that disk will automatically take over when you remove the
> failing disk.
> It would also be reasonable to simply wait for the disk to fail. When
> that happens the array will be keep running. When the disk does fail
> the system will use the hot spare to rebuild the array.
> The short answer is your way will work but it not necessarily.
> -Paul
> 
> On 3/10/06, Ming Zhang <mingz@ele.uri.edu> wrote:
> > Hi folks
> >
> > I have a raid5 array that contain 4 disk and 1 spare disk. now i saw one
> > disk have sign of going fail via smart log.
> >
> > so i am trying to do this
> >
> > 1) pull that disk (A) out
> > 2) using dd to copy that disk (A) to another same one (B);
> > 3) put disk (B) back to raid5 and assume that bitmap can help me resync
> > quickly.
> >
> > now my question is
> > 1) can this achieve my goal?
> > 2) is there any better/correct way?
> >
> > thanks!
> >
> > Ming
> >
> >
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