Re: [PLUG] Things to correct when copying over a filesystem with rsync?

[Greg Helledy <gregsonh@gra-inc.com>]

> Also, I'd hesitate to use the label "RAID-1" to describe your setup.
> These are not really mirrored drives, in that anything you do to the
> one isn't automatically reflected on the other, and you don't get the
> other benefits of RAID like increased read performance.  There is
> nothing wrong with how you're doing it, though you do need to be
> careful to keep them equivalent. 

OK Rich, I have to admit that I did think I have RAID 1 with mirrored 
drives.  Isn't that what I have if I use mdadm to create a device 
labeled as raid 1?  Is there a link I should read to understand the 
difference between what I think I have and what I actually have?

I have the machines set to email me periodic reports, which look like this:

> RAID Status:
> ============
>
> Date:               Oct 13 2017 09:00:03 UTC
> Status:             Clean
>
> Array         Size          Mount         Level         RAID Status
> -----------------------------------------------------------------------
> /dev/md126    951214MB      /             RAID-1        Clean
> /dev/md127    476MB         /boot         RAID-1        Clean 



A related question:  For the purposes of backup I can deal with using 
two drives to exactly duplicate my setup (two identical physical drives, 
each with three partitions, 1 X 4 GB, 1 X 1 GB, 1 X (remainder of 
space), with the first being swap, the second being used to create 
/dev/md0 across the drives, as /boot, and the third being used to create 
/dev/md1 across the drives, as /.)

For testing of third-party software install and upgrade, and training 
staff on use of said software, I'd like to simplify things down to a 
single drive configuration, to produce a drive image suitable for 
VMWare/VirtualBox.

If you wanted to go from the two-drive configuration with mdadm 
partitions across them to a single-drive configuration (no raid), and do 
this by creating a copy (leaving the existing drives untouched), what's 
the best way?  I don't care whether I use a single physical hard drive 
first and then make an image of it, or go directly to an image.  Could I 
copy the contents of /dev/md0 and /dev/md1 to a /dev/sda1 and /dev/sda2 
with rsync?  Would that eliminate the metadata associated with the mdadm 
partitions?  This is ClearOS 6 (a clone of CentOS 6), 64-bit.  I will be 
repeating the process with ClearOS/CentOS 7.  Links are fine.

--
Greg Helledy
GRA, Incorporated
P:  +1 215-884-7500
F:  +1 215-884-1385
www.gra.aero


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