Backups [was Re: Is tape dead?]

Alexander Schreiber als at
Thu Sep 24 17:30:17 CDT 2015

On Tue, Sep 15, 2015 at 03:19:27PM -0400, Mouse wrote:
> > I think a more important issue in backing up is "How many GENERATIONS
> > to you keep around?"
> For many purposes, that's an important consideration, yes.  There's
> something (small) I back up weekly for which I keep the most recent
> seven backups, the oldest backup in each of the most recent twelve
> months, and the oldest backup in any year.  I'm considering something
> of the sort for my house backups - live replication to a backup host,
> with a once-a-week freeze of the replica, storing past replica drives
> on a scheme somewhat like the above.
> > I back up my original work or valuable reference sources.  No
> > pictures or movies.  When you consider how much *original* work
> > anyone does during a lifetime, it's surprisingly little.
> Pictures and movies can be original work - perhaps not for you,
> certainly mostly not for me (I have a few original pictures, but only a
> few), but I know graphic designers and photographers who have probably
> produced at least a gigabyte of original pictures each by now.  And
> people into video production....

A _gigabyte_? *ROFLBTC*

With a modern DSLR (especially if you care about data quality and have
it set to store both high quality .jpeg and RAW files), a day of moderate
shooting can easily produce a couple gigabytes of data. The D800 will
happily write around 50-60 MB _per_ picture (15 MB .jpeg, 42 MB .nef in
a typical example). Granted, out of a few dozen (or hundreds, if you
are a professional), only a few pictures are actually really good and
worth keeping, but why throw it away when it might be useful and storing
it is cheap?

> > Related to the subject of backup devices, I've been seeing stupid-low
> > prices on SSD using MLC flash.  How reliable are these things?  I'm
> > still of the spinning rust persuasion, right now.
> So am I.  I don't trust multi-level for anything more than passing a thumb
> drive to a friend or the like (where failure carries a very low cost)
> and I mostly don't trust wear-leveling algorithms yet, so I have little
> use for flash, certainly not for backups.
> Besides, even stupid-low SSD prices are still, in my admittedly limited
> experience, well above spinning-rust prices.  The advantages of flash
> (random access and physical ruggedness) aren't very important for most
> backup applications, so price (and burnt-in technology, to some extent)
> win out for my purposes.

Flash is great if you want high bandwidth and _massive_ IOPS (so it helps
speeding up your workstation/laptop). It is also nice for being basically
shock resistant (so dropping your running laptop on the bed is no problem).

But for long term storage? Rotating rust. For cheap bulk storage? Rotating
rust. Also, flash tends to have rather abrupt failure patterns, as in:
now it works just fine, now it is dead. Rotating rust tends to give you
at least some warning that you need to replace the disk _now_.

Kind regards,
"Opportunity is missed by most people because it is dressed in overalls and
 looks like work."                                      -- Thomas A. Edison

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