Questions[mdadm](ubuntu)

I would like to install Ubuntu 20.04 Focal Fossa on a machine with two hard disks using RAID 1.

Unfortunately it seems this doesn't work. If I use the "Create Software RAID (md)" option and select both my disks the installer tells me:

If you put all disks into RAIDS or LVM VGs, there will be nowhere to put the boot partition.

I found this detailed answer about 18.04 but the problem with this and similar findings on the subject is that Focal dropped the alternative installer so the required partitioning options are gone.

What options do I have to accomplish this?

I created a RAID with:

sudo mdadm --create --verbose /dev/md1 --level=mirror --raid-devices=2 /dev/sdb1 /dev/sdc1
sudo mdadm --create --verbose /dev/md2 --level=mirror --raid-devices=2 /dev/sdb2 /dev/sdc2

sudo mdadm --detail --scan returns:

ARRAY /dev/md1 metadata=1.2 name=ion:1 UUID=aa1f85b0:a2391657:cfd38029:772c560e
ARRAY /dev/md2 metadata=1.2 name=ion:2 UUID=528e5385:e61eaa4c:1db2dba7:44b556fb

Which I appended it to /etc/mdadm/mdadm.conf, see below:

# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#

# by default (built-in), scan all partitions (/proc/partitions) and all
# containers for MD superblocks. alternatively, specify devices to scan, using
# wildcards if desired.
#DEVICE partitions containers

# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

# instruct the monitoring daemon where to send mail alerts
MAILADDR root

# definitions of existing MD arrays

# This file was auto-generated on Mon, 29 Oct 2012 16:06:12 -0500
# by mkconf $Id$
ARRAY /dev/md1 metadata=1.2 name=ion:1 UUID=aa1f85b0:a2391657:cfd38029:772c560e
ARRAY /dev/md2 metadata=1.2 name=ion:2 UUID=528e5385:e61eaa4c:1db2dba7:44b556fb

cat /proc/mdstat returns:

Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] 
md2 : active raid1 sdb2[0] sdc2[1]
      208629632 blocks super 1.2 [2/2] [UU]

md1 : active raid1 sdb1[0] sdc1[1]
      767868736 blocks super 1.2 [2/2] [UU]

unused devices: <none>

ls -la /dev | grep md returns:

brw-rw----   1 root disk      9,   1 Oct 30 11:06 md1
brw-rw----   1 root disk      9,   2 Oct 30 11:06 md2

So I think all is good and I reboot.

After the reboot, /dev/md1 is now /dev/md126 and /dev/md2 is now /dev/md127?????

sudo mdadm --detail --scan returns:

ARRAY /dev/md/ion:1 metadata=1.2 name=ion:1 UUID=aa1f85b0:a2391657:cfd38029:772c560e
ARRAY /dev/md/ion:2 metadata=1.2 name=ion:2 UUID=528e5385:e61eaa4c:1db2dba7:44b556fb

cat /proc/mdstat returns:

Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] 
md126 : active raid1 sdc2[1] sdb2[0]
      208629632 blocks super 1.2 [2/2] [UU]

md127 : active (auto-read-only) raid1 sdb1[0] sdc1[1]
      767868736 blocks super 1.2 [2/2] [UU]

unused devices: <none>

ls -la /dev | grep md returns:

drwxr-xr-x   2 root root          80 Oct 30 11:18 md
brw-rw----   1 root disk      9, 126 Oct 30 11:18 md126
brw-rw----   1 root disk      9, 127 Oct 30 11:18 md127

All is not lost, I:

sudo mdadm --stop /dev/md126
sudo mdadm --stop /dev/md127
sudo mdadm --assemble --verbose /dev/md1 /dev/sdb1 /dev/sdc1
sudo mdadm --assemble --verbose /dev/md2 /dev/sdb2 /dev/sdc2

and verify everything:

sudo mdadm --detail --scan returns:

ARRAY /dev/md1 metadata=1.2 name=ion:1 UUID=aa1f85b0:a2391657:cfd38029:772c560e
ARRAY /dev/md2 metadata=1.2 name=ion:2 UUID=528e5385:e61eaa4c:1db2dba7:44b556fb

cat /proc/mdstat returns:

Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] 
md2 : active raid1 sdb2[0] sdc2[1]
      208629632 blocks super 1.2 [2/2] [UU]

md1 : active raid1 sdb1[0] sdc1[1]
      767868736 blocks super 1.2 [2/2] [UU]

unused devices: <none>

ls -la /dev | grep md returns:

brw-rw----   1 root disk      9,   1 Oct 30 11:26 md1
brw-rw----   1 root disk      9,   2 Oct 30 11:26 md2

So once again, I think all is good and I reboot.

Again, after the reboot, /dev/md1 is /dev/md126 and /dev/md2 is /dev/md127?????

sudo mdadm --detail --scan returns:

ARRAY /dev/md/ion:1 metadata=1.2 name=ion:1 UUID=aa1f85b0:a2391657:cfd38029:772c560e
ARRAY /dev/md/ion:2 metadata=1.2 name=ion:2 UUID=528e5385:e61eaa4c:1db2dba7:44b556fb

cat /proc/mdstat returns:

Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] 
md126 : active raid1 sdc2[1] sdb2[0]
      208629632 blocks super 1.2 [2/2] [UU]

md127 : active (auto-read-only) raid1 sdb1[0] sdc1[1]
      767868736 blocks super 1.2 [2/2] [UU]

unused devices: <none>

ls -la /dev | grep md returns:

drwxr-xr-x   2 root root          80 Oct 30 11:42 md
brw-rw----   1 root disk      9, 126 Oct 30 11:42 md126
brw-rw----   1 root disk      9, 127 Oct 30 11:42 md127

What am I missing here?

I use Ubuntu 12.04 on a home server. There are 5 hard drives: one SSD with the OS and 4 HDDs (Samsung HD204UI) configured as a RAID5 using mdadm.

I don't need the RAID very often (say, about once per day in average); it contains multimedia data and some backups, so I decided to put the drives to standby most of the time.

I configured the drives to automatically spin-down after 20 minutes using hdparm, here /dev/sda as an example:

hdparm -S 240 /dev/sda

The output of the command confirmed this:

/dev/sdb:
 setting standby to 240 (20 minutes)

But the problem is that the drive spins down after about 5 seconds (instead 20 minutes) after the last access, and

hdparm -C /dev/sdb

displays:

/dev/sdb:
 drive state is:  standby

Why doesn't the drive wait the 20 minutes as configured? Does it have something to do with the RAID setup? (I don't think so...)

This very short timeout is problematic since it is a RAID5 and when I access a file, it is spread block-wise around the four drives. Since drive 1 isn't needed when drive 2 is read, it went asleep when it will be used the next time (after drive 3 has been read from). So the drives keep spinning up and down the whole time resulting in a throughput near zero.

For the people being concerned about the life of my drives: It will be no problem that the drives are spinned up and down once a day in average since I prefer saving energy and heat over health of the drives (I use RAID5 and the content isn't very important).

We are currently trying to run access the data on a server running a HP Ml110 G5 SATA raid controller, using the latest Ubuntu Live CD. We need to delete a few files to let the server boot into Windows but are unable to mount the partitions.

We can see the individual disks via the disk management program but can not mount the partitions, does anyone have any suggestions?

I am in the process of building my first RAID5 array. I've used mdadm to create the following set up:

root@bondigas:~# mdadm --detail /dev/md1
/dev/md1:
        Version : 00.90
  Creation Time : Wed Oct 20 20:00:41 2010
     Raid Level : raid5
     Array Size : 5860543488 (5589.05 GiB 6001.20 GB)
  Used Dev Size : 1953514496 (1863.02 GiB 2000.40 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Wed Oct 20 20:13:48 2010
          State : clean, degraded, recovering
 Active Devices : 3
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 64K

 Rebuild Status : 1% complete

           UUID : f6dc829e:aa29b476:edd1ef19:85032322 (local to host bondigas)
         Events : 0.12

    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc
       2       8       48        2      active sync   /dev/sdd
       4       8       64        3      spare rebuilding   /dev/sde

While that's going I decided to format the beast with the following command:

root@bondigas:~# mkfs.ext4 /dev/md1p1 
mke2fs 1.41.11 (14-Mar-2010)
/dev/md1p1 alignment is offset by 63488 bytes.
This may result in very poor performance, (re)-partitioning suggested.
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=16 blocks, Stripe width=48 blocks
97853440 inodes, 391394047 blocks
19569702 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=0
11945 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
        4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 
        102400000, 214990848

Writing inode tables: ^C 27/11945
root@bondigas:~# ^C

I am unsure what to do about "/dev/md1p1 alignment is offset by 63488 bytes." and how to properly partition the disks to match so I can format it properly.