Firstly, can you please configure your thunderbird mail client to NOT send
HTML mail?  Or at least send both HTML and plain text?  HTML mail really
screws up the quoting, making it very hard to tell what's quoted and what's
new.

Also, don't bottom-post.  Bottom posting is evil.  And please trim your quotes
to the bare minimum required to provide context for your response - no-one
wants to read the same quoted messages over and over again just because you
couldn't be bothered editing your messages properly.  It tells the reader "I
don't care about wasting YOUR time, as long as I save myself a few precious
seconds".

On Sun, Feb 17, 2019 at 02:08:13AM +1100, Andrew Greig via luv-main wrote:
> This my /etc/fstab
> 
> andrew@andrew-desktop:~$ sudo cat /etc/fstab

You don't need sudo to read /etc/fstab, only to edit it. it's RW by root, RO
by everyone else.

> # /etc/fstab: static file system information.
> #
> # Use 'blkid' to print the universally unique identifier for a
> # device; this may be used with UUID= as a more robust way to name devices
> # that works even if disks are added and removed. See fstab(5).
> #
> # <file system> <mount point>        <type>  <options>          <dump>  <pass>
> /dev/mapper/ubuntu--vg-root /        ext4    errors=remount-ro    0       1
> /dev/mapper/ubuntu--vg-swap_1 none   swap    sw                   0       0
>
> andrew@andrew-desktop:~$ blkid
> /dev/sda1: UUID="sI0LJX-JSme-W2Yt-rFiZ-bQcV-lwFN-tSetH5"    
> TYPE="LVM2_member" PARTUUID="92e664e1-01"
> /dev/mapper/ubuntu--vg-root: UUID="b0738928-9c7a-4127-9f79-99f61a77f515"    
> TYPE="ext4"

If you're running LVM then you don't need to (and shouldn't, see below) use
UUIDs to mount your filesystem.  The device mapper entries provide the same
kind of consistency and uniqueness as a LABEL.

You shouldn't use UUIDs when mounting LVM volumes because any snapshots of
that fs will have the same UUID unless you change the snapshot's UUID with
something like 'tune2fs -U random' (ext4) or 'xfs_admin -U generate' (xfs).


> after hot plugging the two drives (I chose to try this to see if they would
> be picked up and configured in the same way as a USB key is detected. it
> seems that sdb and sdc have been detected
>
> dmesg gives this:
>
> [  279.911371] ata5: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
> [  279.912343] ata5.00: ATA-9: ST2000DM006-2DM164, CC26, max UDMA/133
> [  279.912349] ata5.00: 3907029168 sectors, multi 0: LBA48 NCQ (depth 31/32), 
> AA
> [  279.913799] scsi 4:0:0:0: Direct-Access     ATA      ST2000DM006-2DM1 CC26 
> PQ: 0 ANSI: 5
> ...
> [  331.750805] ata4: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
> [  331.751777] ata4.00: ATA-9: ST2000DM006-2DM164, CC26, max UDMA/133
> [  331.751784] ata4.00: 3907029168 sectors, multi 0: LBA48 NCQ (depth 31/32), 
> AA
> [  331.753212] scsi 3:0:0:0: Direct-Access     ATA      ST2000DM006-2DM1 CC26 
> PQ: 0 ANSI: 5
>
> Since the drives have not been partitioned or formatted, should I just
> download the latest Ubuntu and install as a server, with the two drives
> taking up a RAID config?
>
> Or could I just run gparted and partition and format those disks alone?

I don't see any reason why you'd want to re-install the OS just to add some
drives.

how you partition and format them depends on what you want to do with them.
your two main options are to:

1. Add them as new physical volumes to your existing LVM volume group.  This
would allow you to expand any existing filesystems and/or create new logical
volumes to format and mount (e.g. you could create a new lv, format it with
xfs or ext4, and mount it as /media to store video & music files)

2. Partition, format, and mount as completely separate filesystem(s). e.g. if
you just want somewhere to store video or music files.  This could be done
using any filesystem, with or without RAID (either via mdadm, or by creating a
new LVM volume group, or even with btrfs or zfs)



I'd guess that the only reason you're using LVM is because that was the
default option when you first installed Ubuntu.  It doesn't seem like you're
familiar enough with it to have chosen it deliberately.  IMO unless you know
LVM well, you're generally better off with btrfs - like ZFS, it's a filesystem
that has the features of software RAID and volume-management built in, and
is much easier to use than dealing with mdadm + lvm2 + filesystem utilities
separately.

BTW, you may be tempted to use some variant of RAID-0 (linear append or
striped) to combine the two 3TB drives into one 6TB filesystem.  Don't do
that unless you're willing to risk that a single drive failure will lose
*everything* stored on that 6TB.  RAID-0 is NOT safe to use for any data of
any importance.  The only reason to use it is if you need a large amount of
fast storage for temporary files....and an SSD will be much faster than that
anyway.

(NOTE: data stored on striped raid-0 is effectively unrecoverable in case of a
single drive failure. With linear append, recovery of most of the data stored
on the non-failed drive is a PITA but possible. Striped gives a performance
boost as reads and writes are spread across both drives so is roughly twice as
fast as a single drive. Linear does not, as data is written first to one drive
and then onto the second drive when the first fills up)

So, either use RAID-1 (giving you a total of 3TB of usable space, with
everything mirrored on both drives for redundancy/safety) or two separate
filesystems of 3TB each.

> I am puzzled by the almost empty fstab - when I was running OpenSuse the
> fstab was quite large.

it's not something to worry about.

The size of /etc/fstab depends on how many filesystems and swap-devices needed
to be auto-mounted at boot. your previous suse system was probably partitioned
to have separate filesystems for /, /home, /usr, /var, /tmp and/or other
common mountpoints.

This was common practice back when drives were small (filesystems were often
actually on separate drives, not just partitions), but is uncommon and
not recommended these days. The hassles involved in having multiple small
partitions (largely the risk of running out of space on one partition while
still having plenty free on other partitions) tend to greatly outweigh the
minor benefits.

craig

--
craig sanders <[email protected]>
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