[CentOS] External Backup Systems?

Mon Sep 28 02:17:23 UTC 2009
M. Hamzah Khan <hamzah at hamzahkhan.com>

On Sun, 2009-09-27 at 21:10 -0400, Robert Heller wrote:
> At Sun, 27 Sep 2009 23:40:17 +0100 CentOS mailing list <centos at centos.org> wrote:
> 
> > 
> > 
> > 
> > Hey everyone,
> > 
> > My home server just had a disk failure a few weeks ago and like a lot of
> > people I haven't ever really made backups on a regular basis. So I was
> > looking into backup solutions which will save me from this situation
> > again.
> > 
> > Now I have Bacula setup, and backing up my files onto my home server.
> > 
> > Although this works great, I have one issue: The disk in my server was
> > the one that actually failed, and so, even with RAID1, could fail again.
> > So to get around this I wanted to backup to external media aswell.
> > 
> > I don't really think external hard drives are that great considering
> > they are just as reliable as internal hard drives which would be
> > pointless as RAID1 should be reliable enough in that case.
> 
> The point to using an external hard drive is that unlike the internal
> one(s), the external one(s) would be 'idle' most of the time (only
> active during the actual backup process, which would be a once every n
> time units (once a day, once a week, whatever).  Depending on the
> technology in use, 'inactive' can mean unmounted, sleep mode, powered
> off, disconnected, etc.

Thats true. Although I wanted to avoid hard drives mainly because they
seem to have a failure rate which I'm not too comfortable with. 

In the last 7 months, I've had to replace at least 9 disks, some due to
a bad head which dropped and scrached a platter (although this was due
to that model having a problem during manufacturing) and some due to bad
sectors. Both of these issues can occur in external drives regardless of
whether they are active or even switched off.

I've actually had issues with external drives in the past too, and have
heard alot storys from friends and family who have had such issues too
with external drives. The additional to spin ups and spin downs and
extra knocking around doesn't really help keeping data safe. :)

I'm beginning to get the feeling that considering cost, storage space,
and realiablilty the only really feasible solution would be to use hard
drives in RAID5 or 6 with a large redundancy group.

I guess the likelyness of more than two disks failing at the same time
is quite slim, especially if I have a large redundancy group. I could
always keep a spare disk so if one disk fails I can replace it ASAP,
reducing the chances of data loss even more.

> > 
> > Backing up to DVDs are quite unreliable too, a simple scratch could
> > render the backup useless. Also it would require quite a lot of DVDs to
> > backup my data (at least 500GB!).
> 
> The clue here is 'Jewel Cases!'  Keep your CDs and DVDs in Jewel Cases. 
> Don't store CDs and DVDs in sleves or on a spindle or other 'low cost'
> option.  Use a proper Jewel Case.

I do use proper jewel cases, but even so I have found they aren't
perfect at at keeping discs scratch free, besides using 63 dual layer
DVDs to backup 500GB worth of data on a regular basis would really be a
pain. :D

> > 
> > The only other option I could think of is to use tapes, but this option
> > can be quite pricy for a home user.
> 
> Tapes are actually the worst option.  All maner of failure modes, unless
> you go to extreme measures to protect them (which talks it from a pricy
> option to an imposibly pricy option).
> > 
> > So I was wondering what you guys use for external backups for a home
> > system containing at least 500GB worth of important data?
> 
> I don't have disk that ginormous (and cannot imagine having disks that
> size).  I have a 73gig SCSI system disk, that I do monthly fulls and
> daily incrementals to an enternal 120gig SATA 2.5" disk in an USB
> enclosure.  I run a cron job that uses dump and a Tower Of Hanoi
> sequence.  Monthly I manually burn DVDs of the previous months backups.

I actually have 4x1TB disks, but only 500GB is important.

The rest is historical stuff I keep for reference which although is
unreplaceable, it would not be a huge loss if it were to be damaged. :)

> > 
> > Regards
> > 
> > Hamzah
> 
-- 
M. Hamzah Khan
RedHat Certified Engineer Number: 804005539516829
Email: hamzah at hamzahkhan.com
URL: http://www.hamzahkhan.com
Mobile: +44 (0)7525663951
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