Re: Where do I find the definitive man page for mdadm?
On Friday 12 November 2021 11:56:48 Dan Ritter wrote:
> Andy Smith wrote:
> > On Fri, Nov 12, 2021 at 09:22:12AM -0500, Gene Heskett wrote:
> > > mdadm --create --verbose /dem/md0 --level=10 --raid-devices=4
> > > /dev/sde /dev/sdf /dev/sdg /dev/sdh
> > >
> > > should work.
> >
> > You may want to create identical partitions on each of the devices
> > first, and use those instead of the raw unpartitioned devices.
> >
> > The reason is that there is hardware (primarily motherboards) out
> > there that get upset when they see a drive without a partition
> > table, and just blindly make one, which corrupts your RAID. There
> > are ASRock motherboards which are known to do this at every boot.
>
> There's also the fact that disk manufacturers are notoriously
> unable to commit to the same size disks across models. A RAID
> expecting 4 identical 1,024,000,048,576 byte disks might be
> unhappy when you have to substitute in a 1,016,000,000,384 byte
> disk from the same manufacturer -- but if you created partitions
> that were all 1,000,000,000,000 in size, everyone will get
> along.
>
> -dsr-
Dan:
Forced to reboot to see if that would enable me to setup 2 partitions per
disk that failed as the raid label overides any write perms, its locked
for the other disk managers although fdisk was able to create and w rite
an empty GPT table, which did not release the raid locks.
So the ultimate hammer is now zeroing /dev/sde. At a rather glacial pace.
Once that is done, I'll setup a 900g partition on each of /dev/sde|f|g|
h1, and the remainder for the snapshots, called /dev/sde|f|g|h2. I was
able to create an empty GPT table with fdisk and write it without being
denied. I'll do the same with the other 3, and
nuke /etc/mdadm/mdadm.conf, then do the /dev/md0 creation again
with /dev/sde|f|g|h1 and md1 with the same list replacing the 1 with a
2. Then format md0 and md1. Will this satisfy everything?
But now the real write speed is being tested, and it will take nearly 40
minutes to zero each drive, its used up the write buffer. Or /dev/zero
is glacial.
1000204886016 bytes (1.0 TB, 932 GiB) copied, 2040.6 s, 490 MB/s
=34 minutes
And dd used to have a progress bar, but no mention in the man page, when
did that go away?
Its looking as if I'll have to reboot after zeroing all 4 of them, nuking
mdadm.conf first. /dev/sde is still locked by the raid. Is there a
quicker way to undo the creation and get my drives back to square zero
so I can start all over?
Thank you.
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>
Reply to: