[GTALUG] Computer wierdness

[William Park]

On Sat, Aug 29, 2015 at 10:34:24PM -0500, o1bigtenor wrote:
> On Sat, Aug 29, 2015 at 9:30 PM, Lennart Sorensen <
> lsorense at csclub.uwaterloo.ca> wrote:
> > What entry do you have for your raid stuff in /etc/fstab?
...
> nothing listed for md0 or md/0

You can always add it.  But, if manual mounting doesn't work, then
/etc/fstab won't work either.

> > And as already said, software raid does NOT use /dev/dm devices, it uses
> > /dev/md devices.  dm is for device mapper, which you will see if you use
> > dmraid (which I think most people have fortunately stopped doing), or lvm
> > (which many people are using) or encrypted disks (which some people use).
> >
> > What does fdisk -l /dev/md0 show?  Did you partition the raid or is the
> > filesystem on the full raid?
> >
> 
> 
> # fdisk -l /dev/md0
> Disk /dev/md0: 1.8 TiB, 2000403038208 bytes, 3907037184 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes
> I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
> Disklabel type: gpt
> Disk identifier: 1EB47793-0CDF-4E16-AE84-33EC825AC448

> sdb
> ??????sdb1  linux_raid_member debianbase:0 79baaa2f-0aa2-b9fa-18e2-ea6b6e2846b3
>   ??????md0
> sdc
> ??????sdc1  linux_raid_member debianbase:0 79baaa2f-0aa2-b9fa-18e2-ea6b6e2846b3
>   ??????md0
> sde
> ??????sde1  linux_raid_member debianbase:0 79baaa2f-0aa2-b9fa-18e2-ea6b6e2846b3
>   ??????md0
> sdf
> ??????sdf1  linux_raid_member debianbase:0 79baaa2f-0aa2-b9fa-18e2-ea6b6e2846b3
>   ??????md0

There is no filesystem on /dev/md0.  It seems that it has GPT table with
no partitions.  If you do 
    gdisk -l /dev/md0
you'll probably get similar result as 'fdisk -l'.  

In that case, you have to follow through and create partitions on
/dev/md0.  This is similar to regular harddisk /dev/sda with empty MBR
table, where you have to follow through and create partitions /dev/sda1,
etc.

If you intend to use the entire /dev/md0, then wipe off GPT markers
using 'gdisk' ("expert" screen -> "zap" option)
-- 
William