Re: MDADM RAID1 of external USB 3.0 Drives
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Hi,
I'm going to address a number of things here....
First off, I used to use this script [1], with an entry in /etc/rc.local
to kick it off on boot. My goal was to start the RAID1 array only if 2
members could be found (minimum), I added a 3rd member that was for
backup. My process was to:
a) shutdown the box
b) remove the /oldest/ drive
c) move drives 1 and 2 along the /chain/
d) restart the system with only 2 drives attached
e) add a drive from off-site storage into position
f) let it start the array with two disks ...
and then add the 3rd one to re-sync the data.
Here is the supporting /etc/rc.local entry for the mount script:
nohup /usr/local/bin/mount-external-raid-devices.sh 2>&1 >/dev/null &
And this is what the parameter file looked like:
md0-vg-external-1-u1-wrk 06fd3d46-4c33-7670-edd8-d016611227ea 2 60
When all three disks were up to date, I would do the process again. I
never wanted the RAID1 array to start if it only found one disk.
Sometimes one or more of the external USB 2.0 (at the time) drive(s)
wouldn't fire up properly, hence the need for the script.
I was using an older Dell GX520 box, I later started using a HP
MicroServer N54L -- these boxes are very, very cheap and come with 2GB
of RAM, which should be plenty for this type of use. However, I found
out that I could install 16GB of RAM in to it and I like to max out RAM
when I can, so I did that; the RAM wasn't cheap, but it did work
regardless of HP saying it was only good for 8GB max. Now the cost of
the N54L was around the same as recent a 4TB WD Red drive, only slightly
more. The N54L doesn't have any USB 3.0 ports, but you can install a
card for it if you need one. I've since started using a different box,
Thecus N4800eco ... they are more expensive, but still good value and
they do have USB 3.0 ports available as well as a nice internal SATA
type stick, which is ideal for /boot file system and I can use 4 large
capacity disks with LUKS (root file system is LUKS too).
Whilst it is usually quite easy to find older server class hardware at
bargain prices (compared to new), it is often the case that older
hardware is slower and much less power efficient to newer hardware and
the pricing on lots of new gear has collapsed enough to make buying new
a much better option in many cases.
[1] http://ix.io/epu
Kind Regards
AndrewM
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