From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Leslie Rhorer" Subject: Adding a smaller drive Date: Sun, 28 Jun 2009 13:31:06 -0500 Message-ID: <20090628183111280.HTRN20969@cdptpa-omta01.mail.rr.com> Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids I have a few questions. Some RAID implementations will simply refuse to create or grow an array if all the targets are not precisely the same size. Clearly this is not the case for mdadm. Not all drives of a given "size" are actually precisely the same size, however, and I am using unpartitioned drives for my RAID systems. What happens if I add a drive whose apparent physical size is a bit smaller than the device size used to create the array? Does the resync force a smaller device size? What is the limit for how much smaller a new drive can be than the smallest extant in the array? What if I try to replace a drive in the array with one smaller than the provisioned device size? This would apparently shrink the array some. I take it in such a scenario I should shrink the filesystem on the array before replacing the drive (scary!)? How will I know a-priori this would be the case?