Re: Where do I find the definitive man page for mdadm?
On Fri, Nov 12, 2021 at 09:48:01AM -0500, Gene Heskett wrote:
> On Friday 12 November 2021 08:49:21 Dan Ritter wrote:
>
> > Gene Heskett wrote:
> > > The man page we have goes on and on for megabytes without ever
> > > giving an example.
> > >
> > > I thought maybe it could scan for devices so that I could build an
> > > mdadm.conf but it wont do a --scan by itself.
> >
> > You are looking for
> >
> > mdadm --detail --scan
> >
> Null return on stretch version of mdadm. Supposedly up to date as of an
> hour ago.
>
> > It is in that man page, as an example under --detail.
>
> Not in the stretch man page. And its sounding as if I should do that
> during the bullseye install to get the more capable mdadm, but will the
> devices have the same names? With the reputation for volatility of
> device names a mistake there could destroy 23 years of data.
>
> > > But I don't see an option (or recognize it if it is there) to give
> > > it a controller id and let it make a raid10 out of the 4 identical
> > > drives it could find there.
> > >
> > > If there is such a critter, point me at it please.
> >
> > You have to feed mdadm the drives you want specifically; there's
> > no scattershot approach.
> >
> > Let's say that the drives are /dev/sdf, /dev/sdg, /dev/sdh and
> > /dev/sdi.
> >
> > (You can re-confirm what drive is what via hdparm -i, or
> > smartctl.)
> >
> > If you have data on them, it will be wiped out. You should copy
> > off anything important, and then run wipefs on each of them.
> >
> > Then, creation is
> >
> > # mdadm -C /dev/md0 --level=10 --raid-devices=4 /dev/sdf /dev/sdg
> > /dev/sdh /dev/sdi
> >
> > (assuming you want it named /dev/md0 and there isn't one
> > already)
> >
> > Then you can make a filesystem on /dev/md0 and put it in your
> > fstab, mount it, and copy data over to it.
>
> So mkfs.ext4 /md0 is required, ok
>
> > > What I'd like to do when I install bullseye, is use this raid10 for
> > > the /home partition in the bullseye install.
> >
> > The installer will recognize it as an md RAID and can be told that you
> > want to use it as-is, or you can destroy it and re-create it without
> > data.
> >
> > -dsr-
> Thanks Dan.
>
> 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>
>
Gene
At the point when you want to install Bullseye:
Use an expert install.
set up the disks as RAID 10 first, then use the partition editor to assign
the RAID as /home
At that point, you're done :)
All the very best, as ever,
Andy C.
Reply to: