[Bug 599255] Re: dmraid fails to read promise RAID sector count larger than 32-bits

[Greg Turner]

This bug is ancient, and perhaps nobody cares anymore, but I've figured
out a bit more about where we are left with respect to this.

dmraid userland always assumes that the sector size is 512.  It is a
hard-coded constant value.

Meanwhile, in kernel land, dm devices always map their sector sizes,
both logical and physical, to the logical sector size of their
underlying devices.

Perhaps in order to deal with this discrepancy, there is code in dmraid
userland to ignore any drive whose sector size is not 512.  That code
doesn't get triggered, as in this case the problem is that Promise wants
to virtualize the sector size, as they do in their scsi miniport driver
for windows.

Check out this:

https://www2.ati.com/relnotes/AMD_RAIDXpert_User_v2.1.pdf, (p. 107)

If that's right, we might be able to work around this whole mess, having
our dual-boot cake and eating it, too, by creating multiple volumes of
size less than 2TB, keeping MBR on them (as linux does not grok GPT-
partitioned dynamic disks) and using LDM to piece them together.

For my part, looking at the state the dmraid code and Promise metadata
are in, I'm disinclined to rely on it at all; I'm just going to give up
on fully functional dual-boot, use md-raid, and an emulated NAS if I
need access to my other-system data from Windows.

That stated, I guess, to solve the problem fundamentally, in linux, we'd
either need to extend dmraid to support emulated, metadata-based sector
sizes, both in the kernel and the userland code-bases, or to implement
some hack to change the logical geometry of the physical devices before
setting up these arrays (but see
https://bugzilla.redhat.com/show_bug.cgi?id=624335 which suggests this
might not work, anyhow).

It's hard to see anyone putting that kind of effort into the
increasingly marginalized dm-raid framework so I wouldn't hold my
breath...

** Bug watch added: Red Hat Bugzilla #624335
   https://bugzilla.redhat.com/show_bug.cgi?id=624335

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https://bugs.launchpad.net/bugs/599255

Title:
  dmraid fails to read promise RAID sector count larger than 32-bits

Status in “dmraid” package in Ubuntu:
  Triaged
Status in Baltix GNU/Linux:
  New
Status in “dmraid” package in Fedora:
  New

Bug description:
  I have two amd sb7*** motherbord. I tryed two case.

  I use raid0(1.5TB x 3=4.5TB) by bios(SB7*0).

  I partitioned two array. 2.0TB(A) and 2.5TB(B).

                     win7-64
                     winxp32    ubuntu10.4 /fedora13
  ------------------------------------------------------------------
  raid-A 2.0TB   ok              ok          all capacity OK
  raid-B 2.5TB   ok (all)       no*1      only 300GB(NG)
  ------------------------------------------------------------------
  *1=ubuntu knows only 300gb. fedora too.

  ubuntu x64/Fedora13 x64,by DMRAID

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