[Bug 1054948] Re: dmraid broken for large drives

[Jan Kleinsorge]

But wouldn't that simply only imply that dmraid and mdadm are not supposed to co-exist? I'm a bit puzzled about this change. As far as I understand this, the auto-assemble rules have been removed just to guarantee the function of dmraid - temporarily or not. 
Automated installation procedure aside, it is currently not possible to remove dmraid and add mdadm to get an imsm 1.3 (external metadata) running out of the box, right? If no dmraid is present, the cut-down of mdadm does not seem necessary.

It seems this can also be user-fixed without jumping through many hoops
by restoring previous rules, right?

>From my perspective it then boils down to the problem that, even if
auto-assembly would be enabled, mdadm currently does not support the
root being member of the array itself. As I mentioned in 1028677, mdmon
is missing in the initrd which prohibts the any assembly at that point.
The effect is that mdadm sets of read-only devices, instead of auto-
read-only. With adding mdmon this boots but during shutdown the array
seems to be taken down too early so the system does not finish that
gracefully. There have been attempts to fix this in debian (1054773).
See also [1].



[1] http://www.spinics.net/lists/raid/msg37335.html

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to mdadm in Ubuntu.
https://bugs.launchpad.net/bugs/1054948

Title:
  dmraid broken for large drives

Status in “mdadm” package in Ubuntu:
  New

Bug description:
  Attempting to set up a fresh Quantal system on a system with Intel 'fakeraid' (imsm, 1.3) and 3TB SATA RAID1. When running the live CD, dmraid identifies the drives as being of size 746GB (Same effect with a Windows 7 setup without loading the corresponding Intel drivers prior to partitioning). 
  dmraid -an does not release the mappings. The work-around for the installation is to boot with nodmraid, install mdadm and assemble manually prior to starting the installation. dmraid seems to be severly broken for a pretty much standard PC setup. 
  mdadm can handle Intel imsm firmware-backed RAID just fine. 

  After installation, several measures still have to be taken when the system /root is also part of that array/. See #1054773 and references for major issues regarding this.
   
  SInce mdadm is actively supported by Intel and dmraid is at best in a maintenance state, deprecation of dmraid in favor of mdadm would be welcome.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/mdadm/+bug/1054948/+subscriptions