From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Majed B." Subject: Re: Swapping a disk without degrading an array Date: Mon, 25 Jan 2010 15:25:58 +0300 Message-ID: <70ed7c3e1001250425n6b6136ddr261a95042584df72@mail.gmail.com> References: <1264421475.30742.49.camel@test.apertos.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1264421475.30742.49.camel@test.apertos.eu> Sender: linux-raid-owner@vger.kernel.org To: =?UTF-8?Q?Micha=C5=82_Sawicz?= Cc: linux-raid List-Id: linux-raid.ids There's a technique called active spare, and is already available on some hardware RAID controllers. It keeps the hot spare in sync with the array, such that in an event of a disk failure, the spare kicks-in immediately without wasting time for a resync. I think what you're proposing is similar to the following scenario: array0: (assume raid5): disk0, disk1, disk2, disk3(spare) array1: (raid1): disk0, disk3 Though I'm not sure if it's feasible to nest raids or have a disk to be a member of 2 arrays at the same time. I think it was proposed before, but I donno about its priority. 2010/1/25 Micha=C5=82 Sawicz : > Hi list, > > This is something I've discussed on IRC and we achieved a conclusion > that this might be useful, but somewhat limited use-case count might = not > warrant the effort to be implemented. > > What I have in mind is allowing a member of an array to be paired wit= h a > spare while the array is on-line. The spare disk would then be filled > with exactly the same data and would, in the end, replace the active > member. The replaced disk could then be hot-removed without the array > ever going into degraded mode. > > I wanted to start a discussion whether this at all makes sense, what = can > be the use cases etc. > > -- > Cheers > Micha=C5=82 (Saviq) Sawicz > --=20 Majed B. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html