From mboxrd@z Thu Jan  1 00:00:00 1970
From: Phil Turmel <philip@turmel.org>
Subject: Re: Fwd: manually destriping a 4 drive raid5 with one missing drive
Date: Fri, 23 Oct 2015 13:49:39 -0400
Message-ID: <562A7333.9010702@turmel.org>
References: <CA+sqOsbjE4MLa7NXG6hxpzE1m-ZNbcJVNjK51WKCQMhwNgimhg@mail.gmail.com>
 <87fv19m7he.fsf@notabene.neil.brown.name>
 <CA+sqOsZJbvyAW6=CSG5EikhmDPt+Onjpm+VvBNPMKFmVi-ZQ8g@mail.gmail.com>
 <CA+sqOsZfjz0wTei+6qiv+zxXt7TA_GMO8EQ=v0EeDGFpqLrWRg@mail.gmail.com>
 <20151023155324.GA2555@lazy.lzy>
 <CA+sqOsYBbOwn5tJfygAR0MDCQPpd4w61XPGBLv8Mme8cT_HL8A@mail.gmail.com>
 <CA+sqOsY1Q4e3vNy4rmqjndsOStSGOg4JpqWBm4TTEvRdOmTkbQ@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Return-path: <linux-raid-owner@vger.kernel.org>
In-Reply-To: <CA+sqOsY1Q4e3vNy4rmqjndsOStSGOg4JpqWBm4TTEvRdOmTkbQ@mail.gmail.com>
Sender: linux-raid-owner@vger.kernel.org
To: Marek <mlf.conv@gmail.com>, Linux-RAID <linux-raid@vger.kernel.org>
List-Id: linux-raid.ids

On 10/23/2015 12:20 PM, Marek wrote:
> Not sure if it's destrip or destripe but it's basically like puzzle
> you take a block from each drive according to the layout you are using
> e.g. Left symmetric and then write it down in that order computing
> missing blocks from parity blocks - this way you would write an image
> which you can mount without using mdadm. Data restoration companies
> are using this technique.

No special tool required.  Obtain a new drive big enough to hold your
entire array and 'dd' from /dev/mdX to your new drive.

{ BTW: convention on kernel.org is to reply-to-all, trim unnecessary
context, and either bottom post or interleave your reply. }

Phil