building a RAID system - yup

Joseph Landman landman at scalableinformatics.com
Thu Oct 9 09:48:10 EDT 2003


On Thu, 2003-10-09 at 07:26, Robert G. Brown wrote:

> users tapes of special areas or data on request.  The tape system is
> expensive, but a tiny fraction of the cost of the loss of data due to
> (say) a server room fire, or a monopole storm, or a lightning strike on
> the primary room feed that fries all the servers to toast.

Monopole storm... (smile) I seem to remember (old bad and likely wrong
memory) that Max Dresden had predicted one monopole per universe as a
consequence of the standard model.  Not my area of (former) expertise,
so reality may vary from my memory ...

[...]

> I don't think a sysadmin is ever properly paranoid about data loss until
> they screw up and drop somebody's data for which they were responsible
> because of inadequate backups.  Our campus OIT just dropped a big chunk

I always ask my customers a simple question:  What is the cost to you to
recreate all the data you lost when your disk/tape dies?  That is I tend
to recommend multiple redundant systems for backup.  I also like to
point out that you can build a single point of failure into any system,
and the cost of recovering from that failure needs to be considered when
designing systems to back up the possibly failing systems.  

If you backup all your systems over the network, and your network dies,
are you in a bad way when you need to restore?  What about, if you back
up everything to a single tape drive, and the drive dies (and you need
your backup).

Single points of failure are critical to identify.  They are also
critical to estimate impact from.  Most folks have a backup solution of
some sort.  Some of them are even reasonable, though few of them are
about to withstand a single failure in a critical component.

My old research group has a tape changer robot and drive from a well
known manufacturer.  Said well known manufacturer recently told them
that since the unit was EOLed about 2 years ago, there would be no more
fixes available for it.  They (the research group) told me that they
were having trouble with it... 

One tape drive, one point of failure.  Tape drive company is happy
because you now have to drop a chunk of change on their new units, or
scour eBay for old ones.



-- 
Joseph Landman, Ph.D
Scalable Informatics LLC
email: landman at scalableinformatics.com
  web: http://scalableinformatics.com
phone: +1 734 612 4615


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