Re: Where do I find the definitive man page for mdadm?
On Sat, Nov 13, 2021 at 08:39:15AM -0500, Gene Heskett wrote:
> And I just found I didn't have an mdadm.conf, and I had figure a
> new -C would have created it. But the last time I ran it, no
> mdadm.conf was created.
>
> So I made a 2 liner from the --scan output. What else should it have?
It can be empty or missing. So the answer to your question is,
"nothing". Mine have this:
CREATE owner=root group=disk mode=0660 auto=yes
HOMEHOST <system>
MAILADDR root
"man mdadm.conf" should tell you what each of those things does.
> ARRAY /dev/md0 metadata=1.2 name=coyote:0 UUID=3d5a3621:c0e32c8a:e3f7ebb3:318edbfb
> ARRAY /dev/md1 metadata=1.2 name=coyote:1 UUID=ddb6ffa2:e068b701:f316cc5f:83938a13
> You indicate that these are not the UUID's to put in fstab, or do I
> miss-understand?
You've clearly read the email you are replying to which said "array
UUIDs are not filesystem UUIDs and do not go in fstab", so I don't
know why you are asking the same thing again.
Array UUIDs are not filesystem UUIDs and do not go in fstab. What is
unclear about this statement that you felt the need to do it anyway?
> Experiment after putting those UUID's into fstab
I still don't understand why, after reading me tell you that they
don't go in fstab, you then put them in fstab.
> @coyote:etc$ mount /home2
> mount: can't find UUID=3d5a3621:c0e32c8a:e3f7ebb3:318edbfb
Guess what - if you put arbitrary nonsense in /etc/fstab, it won't
work.
> root@coyote:etc$ mount /snapshot
> Which nicely demos why I don't trust UUID's.
All you've demonstrated is that if you put garbage in your fstab
then it won't work.
But no one cares whether you "trust UUIDs" or not. You already said
that you wanted to use fs labels, not UUIDs. Great. Do that then.
> But, why didn't it work?
I'm at a loss as to why you have to ask. You are replying to an
email that tells you not to put nonsense in your fstab, you then
show a transcript of you putting nonsense in your fstab, and then
ask why it didn't work. You even, further down, quote me telling you
not to put array UUIDs in your fstab. Is this performance art?
> Why did I have to revert to md0/md1 names to remount them?
'cos given a choice between nonsense and a device node, mounting a
device node is more likely to work.
> > > And for the time being use that UUID in /etc/fstab to mount it to
> > > /home2, right?
> >
> > No, because that is not a filesystem UUID. And you said you wanted
> > to mount the filesystem by label anyway. So put whatever label you
> > chose when you did mkfs (or when you did it from the installer).
>
> I didn't know mkfs can do labels.
If only any of these tools had a man page.
$ man mkfs.ext4
[…]
-L new-volume-label
Set the volume label for the filesystem to
new-volume-label. The maximum length of the volume label
is 16 bytes.
Andy
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