Date: Wed, 11 May 2005 08:58:44 +0530 From: Subhro <subhro.kar@gmail.com> To: Tony Shadwick <tshadwick@goinet.com> Cc: freebsd-questions@freebsd.org Subject: Re: Hardware RAID 5 - Need vinum? Message-ID: <42817BEC.5060901@gmail.com> In-Reply-To: <20050510155942.V34838@mail.goinet.com> References: <20050510155942.V34838@mail.goinet.com>
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This is a multi-part message in MIME format. --------------050800020804070003090502 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 5/11/2005 2:35, Tony Shadwick wrote: > 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. That is what everybody does. It is very much normal. > > 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. I could not understand what you meant by RAID device entry would be larger. The various entries inside the /dev are nothing but sort of handles to the various devices present in the system. If you want to manipulate or utilize some device for a particular device present on your box from a particular application, then you can reference the same using the handles in the /dev. And the handles remains the same in size irrespective of whether you have 1 hard disk or 100 hard disks in some kind of RAID. > 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. The main idea in favor of using Hardware RAID solutions over software RAID solutions is you can let the CPU do things which are more worthwhile than managing I/O. The I/O can be well handled and is indeed better handled by the chip on the RAID controller card than the CPU. If you add another disk to your RAID or replace a dead disk at any point of time, then the RAID card should automatically detect the change and rebuild the volumes as and when required. This would be completely transparent to the OS and sometimes also transparent to the user. Regards S. --------------050800020804070003090502--
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