From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: 3T drives and RAID Date: Sun, 31 Oct 2010 11:30:29 -0400 Message-ID: <20101031113029.226d9e65@notabene> References: <20101030103312.7b5a2107@zealot> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Leslie Rhorer Cc: 'Johannes Truschnigg' , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Sat, 30 Oct 2010 04:21:16 -0500 "Leslie Rhorer" wrote: > Md will automatically treat the oddball drive as if it had .5K > sectors, or does one need to tell ma (or the kernel) to do so? > You don't need to tell the kernel to do anything special - it should just work. md/raid5 (and raid6) do all writes as 4K blocks, 4K aligned (as the stripe-cache is made of pages which are 4K). So that fits perfectly with the new drives. If your filesystem issued a non-aligned read, then it could get down to the device as a non-aligned read, but there is little performance penalty for reads, only writes. And XFS almost certainly does all IO in 4K multiples, so you should be fine. In short: I can see no reason why it shouldn't work smoothly. NeilBrown