Hardware RAID 5 - Need vinum?

[Greg 'groggy' Lehey]

On Tuesday, 10 May 2005 at 16:05:50 -0500, Tony Shadwick wrote:
> I've worked with RAID5 in FreeBSD in the past, with either vinum or a
> hardware raid solution.  Never had any problems either way.
>
> I'm now building a server for myself at home, and I'm creating a large
> volume to store video.  I have purchased 3 200GB EIDE hard drives, and a 6
> channel Promise SX6000 ATA RAID controller.
>
> I know how to set up a RAID5 set, and create a mountpoint (say
> /media/video).
>
> What my concern is when I start to fill up the ~400GB of space I'm giving
> myself with this set.  I would like to simply insert another 200GB drive
> and expand the array, allowing the hardware raid to do the work.
>
> The problem I see with this is that yes, the /dev/(raid driver name)0 will
> now be that much larger, however the original partition size and the
> subsequent slices will still be the original size.  Do I need to (and is
> there a way?) to utilize vinum and still allow the hardware raid
> controller to do the raid5 gruntwork and still have the ability to
> arbitrarily grow the volume as needed?  The only other solution I see is
> to use vinum to software-raid the set of drives, leaving it as a glorified
> ATA controller card, and the cpu/ram of the card unitilized and burden the
> system CPU and RAM with the task.

What you need here is not Vinum (which would replace the hardware RAID
array), but growfs.  You'd need that with Vinum as well.

There have been issues with growfs in the past; last time I looked it
hadn't been updated to handle UFS 2.  If you don't need the UFS 2
functionality, you might be better off using UFS 1 if you intend to
grow the file system.

Greg
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