On Mon, 2020-05-25 at 11:03 -0700, Samuel Sieb wrote: > On 5/25/20 2:25 AM, Patrick O'Callaghan wrote: > > On Sun, 2020-05-24 at 16:22 -0700, Samuel Sieb wrote: > > > On 5/24/20 3:39 PM, Patrick O'Callaghan wrote: > > > > > > > So although the above message says the existing partition table will be > > > > lost, for some reason I'm still getting a partition, while you > > > > apparently didn't. I copied the --create command directly from the man > > > > page. Is this not the "standard" way you mentioned in an earlier reply? > > > > > > That message is a little misleading. What happened was you created an > > > > > > array out of disks with existing data on them. Only the superblock gets > > > > > > rewritten, the rest of the drive just gets resynced, not erased. So > > > > > > your existing partition table is still there. > > > > More than a little misleading. I'd call the message downright wrong. > > I'll consider reporting it to BZ. > > It depends on which drive has the partition table and which drive gets > cloned to. For example, you have one blank drive and one with a > partition table. If the blank one get cloned to the other, then the > partition table gets wiped out. If it goes the other way, then your > raid has a partition table. But even in that case, depending on where > the raid metadata goes and other factors, it could mess up the table or > have it point to the wrong place. It's best to just assume that the > partition table will be invalid even if it appears to still be there. > Unless you're really sure about what you're doing, you should always > reinitialize a newly created raid array, not trusting the existing data.
That decision was taken by mdadm without input from me, i.e. it's the default. I see there is an "--assume-clean" option which would possibly have skipped that step, though the man page doesn't recommend it unless you know what you're doing, which I clearly don't. All the same, saying "the partition table *will* be lost or meaningless after creating array" is certainly wrong. poc _______________________________________________ users mailing list -- users@lists.fedoraproject.org To unsubscribe send an email to users-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org
