[H-GEN] Linux Backup

[Robert Brockway]

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On Sat, 10 May 2003, David Jericho wrote:

> Hard drives, yes, I'll agree. CDs. No.
>
> CDs can suffer the same problems as tape in many ways. I've burnt CDs
> on various different drives over the years, that can only be reliably
> read on that very CD burner. Caveat emptor and all the rest. Same goes
> for DVD.

I've had no problem with CDs but I'll accept not everyone has had my good
fortune.  I don't consider CD/DVD as viable for primary backup for
capacity reasons anyway.  I do occassionally augment my normal backup
regime with CDs.

> As opposed to CD media which simply does not have the capacity for

Exactly.  rules them out for me (and many others).

> What I dislike about the use of disk for backup is that people do get
> lazy, and don't hotswap/unplug the unit simply because it can be

They can (and do) get lazy with any backup system.  In an office
environment I have found this can be solved with formally assigning the
backup procedures to one or more people[1] and making the importance of
the situation known.  This is a human problem, not a computer one.

[1] In an ordered scheme.  Alice does backups (ensuring they go offsite,
whatever).  If Alice is away, Bob covers it.  If Alice & Bob are both away
Charlie covers it.  Don the manager, keeps on eye on it too.

In my previous position (as a contractor) I put myself in as C.

> difficult. How many PCs do you still see with firewire ports only on
> the rear?

They normally have long cables, so the drive ends up sitting beside the
computer.

> Leaving a drive connected to the machine it's responsible for just as
> silly as storing your tape collection in the hot cupboard by the
> stairwell.

Agreed.  Failing to take the backup offsite negates most of the purpose of
a backup.  This can happen with any backup procedure unless it is managed
properly.

> I've always made a point of confirming on a regular basis that my
> backups can be read back on another machine with a similar drive. I consider

This is good practice.  I've seen far too many busiensses that didn't have
access to a 2nd drive unfortunately.  Makes you wonder where they'd get
the drive to restore if they lost the main system too.

> I've also always confirmed that if I use dump under Linux, that I can
> restore it under Solaris, and vice versa. The most interesting and
> particular attributes may not be restored, but what is most important
> to me is the data, not the system particular attributes it may have.
> Same goes for tar and the rest.

Definately.  This is good practice.

> I don't see anything wrong with disk as backup, but I see disk as
> fragile as a tape itself. Drop a disk, and like dropping a tape, you

I think you'll find quantitative data shows that tapes really do fail more
quickly and more often than disks.  Disks aren't perfect but they are
better than tape, in terms of failure rates.

> I'm not sure that I believe in the use of a filesystem on a backup device

This is interesting.  Having a filesystem provides some checks on
writting data.  Some OSes even provide for filesystems on tape drives.

> In anycase, nothing practical yet beats paper for long term storage.

This is true.  So far no magnetic media has shown great potentiasl for
storage past a few decades (CDs included).

> [1] Was it not 2.4.14 that was out for a matter of hours before it
>     wiped a few peoples filesystems?

2.4.15.  A travesty that should never have made it into a production
kernel.  You were ok unless you forgot to sync before you umounted.  Ouch.

Still, I don't see this invalidates the entire argument.  Such a bug could
just have easily been in the scsi tape driver or the MMU or the...

Anyway, looks like we might have to agree to disagree on this one :) I
still firmly believe that external firewire drives are an under-rated and
much maligned backup media.  Nothing said so far discussed discourages me
from my belief that they are more cost effective and more reliable for
small scale off-site storage.  I reserve judgement on large scale (as I
noted earlier in the thread) but I do think they have potential there
also.

Cheers,
	Rob

-- 
Robert Brockway B.Sc. email: robert at timetraveller.org  ICQ: 104781119
Linux counter project ID #16440 (http://counter.li.org)
"The earth is but one country and mankind its citizens" -Baha'u'llah

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