[Bug 1054948] Re: dmraid broken for large drives

Dmitrijs Ledkovs launchpad at surgut.co.uk
Sun Sep 23 12:13:45 UTC 2012

The problem was that after upgrading mdadm, previously working systems
with dmraid fail to boot due to fighting over isms raid drives with
mdadm. There are still many formats supported by dmraid that are not
supported by mdadm, somehow we need to make two co-exist happily.

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  dmraid broken for large drives

Status in “mdadm” package in Ubuntu:

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.

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