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Server: Dell T20 with additional SATA PCI-E controller, 5 SATA drives plugged in at the moment. All GPT partitioned.

System: GNU/Linux Debian 9 Stretch.

Situation: I often change HDD configuration in order to run data extractions from customer formatted drives and such.

Problem: If I unplug some drive(s), and plug in new one(s), I need to edit the file systems file:

/etc/fstab

If I don't do that, the system would hang on boot.

Personal suspicion: If I unplug, say:

/dev/sde

Which is part of one software RAID1 using mdadm, and plug in some other drive, the system, I think, is searching for the original drive, but finds other drive.

The mdadm.conf file follows:

cat /etc/mdadm/mdadm.conf | grep ARRAY -A 1
ARRAY /dev/md1 level=raid1 num-devices=2 metadata=1.2 name=backup-server:1 UUID=319334f9:76d6fccf:d61307bd:2427b6ba
    devices=/dev/sdd1,/dev/sde1

The /dev/md1 detail follows:

/dev/md1:
        Version : 1.2
  Creation Time : Sun Mar 26 17:25:30 2017
     Raid Level : raid1
     Array Size : 976630464 (931.39 GiB 1000.07 GB)
  Used Dev Size : 976630464 (931.39 GiB 1000.07 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Fri Aug 18 13:44:37 2017
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : backup-server:1  (local to host backup-server)
           UUID : 319334f9:76d6fccf:d61307bd:2427b6ba
         Events : 2562

    Number   Major   Minor   RaidDevice State
       0       8       49        0      active sync   /dev/sdd1
       1       8       65        1      active sync   /dev/sde1

Question #1: Is the devices line mandatory and if so, may I address the drives by UUID?

Question #2: Say I re-plug-in the original sde drive to another cable, how to make it still recognized? I think this whole thing should be addressing drives and array by UUID and it would be solved, no? If I am correct, where do I have to change stuff?

  • ARRAY /dev/md1 UUID=319334f9:76d6fccf:d61307bd:2427b6ba is all you need. – frostschutz Aug 18 '17 at 12:25
  • @frostschutz Could you elaborate and make an answer from your comment? – LinuxSecurityFreak Aug 18 '17 at 12:26
  • That's literally it. For each array, just the UUID, nothing else. – frostschutz Aug 18 '17 at 12:39
1

As per frotzschutz' comment

ARRAY /dev/md1 UUID=319334f9:76d6fccf:d61307bd:2427b6ba

is all you need. That's literally it. For each array, just the UUID, nothing else.

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