pef vs dng

Graydon oak at uniserve.com
Mon Oct 5 11:15:30 EDT 2009


On Mon, Oct 05, 2009 at 04:38:08PM +0200, Dario Bonazza scripsit:
> Graydon wrote:
[snip]
>> I've managed to fill two 8 GB cards precisely once; my brain gives out
>> around 600 exposures, as a general rule.  To get to a difference between
>> DNG and PEF storage that adds up to a single 8 GB SD card, you need to
>> take a thousand shots or more on each photographic outing.
>>
>> This does not strike me as an operative difference; maybe I don't take
>> very many shots, I don't know.
>
> What about hard disk space and extra time for backup? 

Well, backup is automated; it doesn't take any of *my* time, if that
follows.  (A combination of rsync and a crontab entry, but there are
ways to do this for any operating system out there.)

> I already have four USB external drives connected to my PC (2x500GB +
> 2x 1TB), and I'm short of space, so I'm going to add two more USB
> units very soon (one unit being the backup for the other one). At this
> shooting pace, I'm adding a couple drives a year. Within 10 years from
> now, I'm planning to have 24 external drives in my small room. Of
> course, I'm going to do something for shrinking that into fewer larger
> units, but I'm afraid of the time for managing copying all those data
> sooner or later. Even before figuring the whole bill, I tend to not
> waste hard disk space.

To a first approximation, disk space is free.  (And disk space
capacity/cost curves should keep on doing what they're doing until 2020
or so, given current information.)

Yes, you have to buy hard drives, but the cost of optimizing disk usage
outside of some very narrow special-purpose uses (like massive blocks of
data from scientific instruments or for financial databases) is
generally way higher than just buying another drive.

I have a 2 TB RAID 10 array in the case and 2 1 TB external SATA drives;
the RAID and the external backup drives, considered as units, each have
about 1 TB of space free.  Since I've got a total of 530 GB of K20D
shots since getting the camera in March of 2008, that should be good for
at least a year or so.  By which point I can swap 2 TB drives into the
RAID array.  (Well, OK, get another RAID controller and build a larger
array, probably, but you know what I mean.)

And I don't delete shots, and I do shoot DNG.

Copying speed, well, USB2 is a dog with short legs; eSATA or USB 3 (or
especially, USB4's optical interconnect version) aren't or won't be, and
I'm pretty sure even Macs let you have eSATA these days.

Time management, well, there shouldn't be any; it should either be a
straight copy of an unambiguous directory structure, such as:

$ROOT/photo/K20D/2008/06/20080621/ with all the shots from the 21st of
June, 2008 in it

or it should be something your photo management application just does
for you; in either case while it takes time it doesn't take interactive
time with the human.  (I know Macs have or can get command-line rsync
for this; don't know about Windows boxen.)

So, yes, there's value in staying organized but the marginal cost of
your time versus 3/8 larger DNG files doesn't strike me as an obvious
win for expending time.

-- Graydon




More information about the PDML mailing list