On 24Dec2019 14:47, Javier Perez <pepebuho@xxxxxxxxx> wrote:
I have my /home partition on a 2TB HDD drive about half full. Should be
doing regular backups but not in the habit.
What is better?
A. Purchase a second 2TB to create a Raid1 mirror or
B. Purchase a second 4TB drive for backup purposes.
If case B, should I get a USB3.0 adapter or similar so that I could just
plug the HDD, let it do the backup and unplug and store it? Or is it better
to install it on another networked pc and do it through the network?
Is there a better, easier, less troublesome option to keep the data safe
that does not involve the cloud?
This is a home network
As pointed out, these are 2 different requirements. My recommendation:
do both. (Yes, more $s, alas.)
Let me describe our home setup.
Our personal machines are Macs which we backup with TimeMachine to
drives which generally live in a drawer (i.e. not online, and less
visible to theft).
Our home server and media machine is an Ubuntu Linux box. The main
storage area is a pair of 8TB drives in RAID1. We like RAID1 because it
means that a single drive works standalone, even without RAID - RAID5
etc distributes the data more complexly. This makes RAID1 handy for
recovery in another machine (eg plugged into a USB cradle).
If you have RAID1 I recommend you have a cron job to monitor it. I run
my chkmdstat script once every 5 minutes; it is silent when things are
good and thus generates an email if a drive fails:
https://bitbucket.org/cameron_simpson/css/src/tip/bin/chkmdstat
We back up the main area to external USB3 drives (we like WD
MyPassports, but there are equivalent products for similar prices; a
nice USB powered 2TB or 4TB drive). We keep 2 backups: an "online" one
which is updated regularly and an "offline" one which lives in a drawer
where accidents won't happen to it.
You'll notice that 2TB < 8TB. (WD now sell a 4TB MyPassport, but that is
still <8TB.)
We divide the main area into different areas for backup (I'm in the
midst of changing this to use a tagging scheme instead of directory
layout) and backup some areas to backup A, some to backup B and so
forth. This manages the space requirement. It sounds like your home
machine is small enough to fit in a single external drive, so you are
spared this pain.
I use histbackup for these backups; it is an rsync wrapper which keeps
multiple historic backups as hardlinked trees named after the backup
date. So a new backup goes: hard link the last tree to the new tree and
rsync into it. Since rsync makes new files for changes this keeps the
hard links for unchanged files and makes shiny new files for changes, so
the cost is incremental.
Histbackup is here:
https://bitbucket.org/cameron_simpson/css/src/tip/bin/histbackup
There are plenty of other similar tools.
These days, to reduce the likelihood of accidental damage to the backups
I like to have the "A1" backup plugged in but not mounted ("A2" is the
second copy which lives in a drawer). This also has the advantage that
provided a backup is not running you are free to unplug or plug in the
external drive at will, because it is unmounted.
The backup script has the form:
if mount /mnt/backupA
then
histbackup into /mnt/backupA/area from /app8tb/area
umount /mnt/backupA
fi
(Obviously the real script reads mountpoints and areas in a loop to do
several backups.)
My fstab has lines for each backup drive, eg:
LABEL=ARCHIVE_1A /mnt/archive1_a xfs user,noauto,noatime 0 0
so that the mounts work; you just have to label the USB drive
filesystems when you make them. I also put a little paper sticker on
each drive to describe it.
Finally, if you have multiple external drives (eg multiple backup drives
for space reasons, or both the 1 and 2 copies plugged in at once) I
recommend doing the backups in series, not in parallel; I've a little 4
port USB4 hub and have had bad experiences trying to run both drives at
once - might be lack of power, might be dodgy hardware, might be USB
driver issues. Anyway, I/O errors ensued.
Cheers,
Cameron Simpson <cs@xxxxxxxxxx>
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