Greg Helledy on 16 Oct 2017 11:25:27 -0700

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

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

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