[Parted-maintainers] Bug#778712: libparted2: Breakage of RAID GPT header

[Phillip Susi]

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On 2/18/2015 4:05 PM, jnqnfe wrote:
> Background ================= I have a 'fake-raid' RAID0 array,
> created from two HDDs using my motherboard firmware. This is not
> used for root, just data.

FYI, unless you have to dual boot with windows, you should avoid using
fakeraid and stick with conventional linux software raid, which is
much better supported.

> sdb and sdc are the RAID members here and the RAID device is
> md126.

Then you need to only manipulate md126 and ignore sdb and sdc.  Most
of what you seem to be reporting involves looking directly at the
individual disks, which you must not do as that will present a
partial/corrupt view of the raid array.  In other words, if the first
few sectors of the raid array map to sdb, then sdb will appear to have
a partition table in its sector 0 that describes a disk that is twice
the size, since this partition table is actually describing the raid
array and not the individual disk.

The one thing you mention that I can't write off as user error is "but
parted is not and seems to be forcibly applying what it believes to be
correct (ignoring the fact that it was only asked to display info, not
modify anything)".  Can you provide more details here?  Exactly what
command did you run and what changed before vs. after?  Parted should
not be modifying anything on the disk unless you tell it to.  Normally
it will throw a warning telling you something is wrong with the disk
and ask if you want it to fix it and you have to answer "fix" for it
to modify the disk.


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