[unisog] Tape backup solutions

Patrick Darden darden at armc.org
Mon Jun 17 17:26:30 GMT 2002

Tapes are prone to mechanical failure--much more so than hard drives.  If
you have a Storagetek archive or something similar, you can set it to
automatically duplicate tapes in case of failure.  You have to dedicate a
drive to "dupe" mode, and a section of storage; e.g. a 10TB unit might
become a 5TB unit, and backup backup tapes are also exchanged.  If you
don't do this, then a tape will fail on you sooner or later--probably
sooner.  This is a big argument against using HFS and tapes as your
primary long term storage solution, vs. a backup solution.

--Patrick Darden                Internetworking Manager             
--                              706.475.3312    darden at armc.org
--                              Athens Regional Medical Center

On Mon, 17 Jun 2002, Peter Van Epp wrote:

> > 
> > 
> > I think hard drives are cheap enough so you could just use NAS to mirror
> > your stuff.  HDs are beginning to get competitive with tapes:
> > 
> > Tapes		$75/40GB		slow, ~1 year shelf life
> > HD		$100/40GB		fast, ~3 year shelf life
> > 
> > 
> > --
> > --Patrick Darden                Internetworking Manager             
> > --                              706.475.3312    darden at armc.org
> > --                              Athens Regional Medical Center
> > 
> 	While this is possible (and in some cases such as petabyte file stores,
> the only practical alternative) there are volume and power issues to think
> about. Tape takes no power (of course neither does disk that is powered off)
> and is much lower volume than tape. This makes multi generations of backup
> more practical which can be important when you are defending against a software
> error (such as subtle file corruption in the NAS unit that isn't noticed for
> several backup periods). Backups aren't only protection against hardware 
> failure typically (otherwise raid and friends would be enough usually) ...
> 	As well a UPS failure that overvoltages (and destroys) your spinning
> disk won't affect a non powered tape. Storing tapes off site is much easier
> (partly because they are less shock sensitive than disk) as well. While a 
> a remote backup site with spinning disk will solve most of these problems (but
> not the software error if both NAS units run the same software ...), you may
> find the TCO is more than tape by the time you factor in the cost of the 
> network pipe between the NASes. There are lots and lots of issues to consider
> on a well designed backup system not only the usual one of a hardware disk 
> failure ...
> Peter Van Epp / Operations and Technical Support 
> Simon Fraser University, Burnaby, B.C. Canada

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