[CentOS] which uuid to specify a raid in fstab

2015-03-07 Thread Negative
I'm confused about which UUID to use to identify a software RAID in fstab.

lsblk -fs shows:

md127p1   ext4c43af789-82aa-49e9-a8ed-acd52b1cdd58 /y
--- md127   ext4  39c20575-4257-4fd7-b5c8-8a15757e9e8e
  --- sdb1  linux_r hostname:0
  af77830e-8cfd-9012-62ce-e57105c3bf6c
  --- sdb
  --- sdc1  linux_r hostname:0
  af77830e-8cfd-9012-62ce-e57105c3bf6c
  --- sdc linux_r hostname:0
  af77830e-8cfd-9012-62ce-e57105c3bf6c


mdadm --detail

gives for both md127p1 and md127

UUID : af77830e:8cfd9012:62cee571:05c3bf6c


I want to add some disks to the server, not to the raid and I wanted to
avoid trouble with the names.

Any help would be appreciated.

Barry
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Re: [CentOS] which uuid to specify a raid in fstab

2015-03-07 Thread Negative
Thanks.



On Sat, Mar 7, 2015 at 4:26 PM, Miguel Medalha miguelmeda...@sapo.pt
wrote:

 Assuming your raid group is /dev/md127, you can run:

 ls -l /dev/disk/by-uuid

 or

 blkid /dev/md127

 and use the ID both will show for /dev/md127

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Re: [CentOS] which uuid to specify a raid in fstab

2015-03-07 Thread Chris Murphy
/etc/fstab needs the UUID for the filesystem volume; so if you use
blkid, find the line with the filesystem type and label you used when
you created the file system, and use the uuid listed after UUID=

The grub.cfg should have a boot parameter mduuid which makes mdadm in
the initramfs aware that it should assemble the array as soon as it
can. It ought to be able to discover what it needs from mdadm metadata
1.x from the member drives, but I'm actually not certain of the role
the /etc/mdadm.conf plays or whether it needs to be baked into the
initramfs these days.

You can use 'systemd-analyze blame' to see if any particular unit file
is waiting for either the fs uuid or md uuid to appear. If so I'd
probably start with just rebuilding the initramfs with a 'dracut -f'.
I'd like to believe on-disk metadata can just be discovered
automatically but...


Chris Murphy
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Re: [CentOS] which uuid to specify a raid in fstab

2015-03-07 Thread Miguel Medalha
Assuming your raid group is /dev/md127, you can run:

ls -l /dev/disk/by-uuid

or

blkid /dev/md127

and use the ID both will show for /dev/md127

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Re: [CentOS] which uuid to specify a raid in fstab

2015-03-07 Thread Chris Murphy
On Sat, Mar 7, 2015 at 5:23 PM, Chris Murphy li...@colorremedies.com wrote:

 The grub.cfg should have a boot parameter mduuid which makes mdadm in

I'm not sure if grub2-mkconfig will automatically detect and add
mduuid to grub.cfg. You can try it. If not then you could add the
entry to the extra boot params line in /etc/default/grub and then
recreate the grub.cfg with grub2-mkconfig -o...

-- 
Chris Murphy
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