On Tue, Mar 12, 2013 at 10:10 PM, Keith Keller <
kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> On 2013-03-12, SilverTip257 <silvertip257@xxxxxxxxx> wrote:
> >
> > I've not had any MegaRAID controllers fail, so I can only say they've
> been
> > reliable thus far!
>
> I think that this is not a helpful comment for the OP. He wants to
> know, in the event the controller does fail, can he replace it with a
> similar-but-possibly-not-identical controller and have it recognize the
>
I've had no problem with various versions of Dell MegaRAID/PERC5i
controllers.
You can swap drives from a PERC5i into a PERC6i for example and things are
peachy. But it is not possible to swap drives from a PERC6i into a PERC5i
controller.
Avoid SAS6/iR controllers ... they are low-end controllers that only
support hardware RAID0 and RAID1.
Ultimately hardware RAID controllers can be a big pain -- just like
anything else it's a good business practice to have spares!
> original RAID containers. Just because you have not seen any failures
> so far does not mean the OP never will.
>
> > You start by failing/removing the drive via mdadm. Then hot remove the
> > disk from the subsystem (ex: SCSI [0]) and finally physically remove it.
> > Then work in the opposite direction ... hot add (SCSI [1]), clone the
> > partition layout from one drive to the new with sfdisk, and finally add
> the
> > new disk/partitions to your softraid array with mdadm.
> >
> > You must hot remove the disk from the SCSI subsystem or the block device
> > (ex: /dev/sdc) name is occupied and unavailable for the new disk you put
> in
> > the system. I've used the above procedure many times to repair softraid
> > arrays while keeping systems online.
>
> This is basically the same procedure for replacing a failed drive in a
> hardware RAID array, except that there is no need to worry about drive
>
I'll argue that the software RAID process is slightly more complex. And it
is crucial that one remember to hot-remove the disk ... after all one
could panic their box by just yanking the drive.
I think that information will be useful to the OP and others, so I posted
it all.
I ought to check the CentOS wiki and see if any/all of those steps are
documented.
> names (since individual drives don't get assigned a name in the kernel).
> But the point is that replacing a failed drive is the same amount of
> on-site work in either scenario, so that should not deter the OP from
> choosing software RAID. (There may be other factors, such as the
> aforementioned write cache on many RAID cards.)
>
> --keith
>
>
> --
> kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx
>
>
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--
---~~.~~---
Mike
// SilverTip257 //
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