Re: Fwd: manually destriping a 4 drive raid5 with one missing drive

[Phil Turmel <philip@turmel.org>]

Hi Marek,

On 10/23/2015 04:46 PM, Marek wrote:
> On Fri, Oct 23, 2015 at 7:49 PM, Phil Turmel <philip@turmel.org> wrote:
>> 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.

> dd from mdX doesn't work i tried it even with testdisk, what you get
> is mixed up data, incomplete files.

Well, that suggests you've done more than just a forced resync.  Pretty
much the only way to get this is to screw up the device order with
"mdadm --create --assume-clean"

You'll need to provide a great deal of data about your array and
precisely what you've done to it.

> { Google mail on iPad doesn't support plain text, who knew :/ }

{Top-posting fixed. Gmail screws this up by default, too.}

Phil