Re: Where do I find the definitive man page for mdadm?
On Saturday 13 November 2021 09:51:05 Andy Smith wrote:
> On Sat, Nov 13, 2021 at 09:28:46AM -0500, Gene Heskett wrote:
> > the next question is why does
> > --scan even report it if its no good? blkid returns different
> > UUID's. Would those work?
>
> Why are you under the impression that every single thing called a
> UUID must work as a *filesystem* UUID?
>
> Lots of things have a UUID. Universally Unique IDentifiers are
> useful things. But not every UUID is a filesystem UUID. This is like
> taking the VIN from your car and putting it in fstab then asking why
> it didn't mount your car as a filesystem.
>
> MD arrays aren't filesystems, they are block devices.
>
> "blkid" does report filesystem UUIDs, according to its manpage, so
> the answer to that one is is yes.
>
> Andy
I wouldn't argue near as loud if it hadn't already been proven to me that
what you call filesystem UUID's are volatile. It happened when I moved a
drive from sda to sdd several years ago. Getting ready to switch to the
next version of debian because I always install to a new drive, which I
installed wheezy on, then put the old drive back in on a different sata
port to get my data copied to the new drive. No boot but single. It took
me 3 days to build an fstab that mounted everything by Labels. When I
finally had a working system again, I ran blkid again, and with the same
drives except the boot drive re-arranged, every UUID blkid reported was
different from what it was in the now commented out lines in fstab.
The downside of now using mkfs to install a label, I didn't use it then
but something else, but mkfs also wipes the drive, so in this case I
hadn't moved anything to it, so I lost nothing reformating to install
the label. The utility, if it wasn't journal-something or other I don't
recall, but it could label a partition that already had content, without
losing that data.
rant on:
That isn't moving forward in any field including computers. This stretch
install uses UUID's to mount the system, and bullseye might also be left
that way, but you can take it to the bank that anything associated with
amanda is mounted by labels. Its simply too big a risk to do UUID
mounts with something that important.
I wrote a wrapper for amanda, and its data is several gigs that are also
backed up after amanda is done. I can lose the boot drive, get in the
pickup and go get a fresh one, put it in and re-install to bare metal,
using a net-install dvd, get the amanda from the repo's and with
amanda's backups, have this system restored to about 2:20 this morning
in time to cook dinner.
Computers were designed to work for you, not against you. This email,
minus the typing I'm doing, will be sent with one click, and one more
takes me to the next unread message. If I can answer, one more click
selects a pm or list reply. Everything else is being done by scripts I
wrote, because computers are supposed to work "for you", not "make work"
for you.
/rant off:
Thanks Andy.
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>
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