Digital archiving tools

Jerome H. Fine jhfinedp3k at compsys.to
Sat Mar 12 23:22:54 CST 2011


 >Shoppa, Tim wrote:

>>Friends don't let friends store their archives on a media that requires physical contact
>>with a read/write head.
>>
>As a data point: All of bitsavers fits on 27 DVD-R's.
>  
>
That is only about 125 GigaBytes?  Is there any possibility of putting 
everything for the
PDP-11 in one set of files?  How much would just the PDP-11 files occupy?

>I'm told that Blu-Ray recordables store 25GB (single layer) or 50 GB (dual layer) but I'm
>not at the leading edge of media adoption. Only in the past year have I grudgingly
>admitted that DVD-R might be halfway decent for everyday use, but I still don't trust
>anything but Gold CD-R for longer term use.
>  
>
I started to use DVD-R media around 2003 for my monthly backup for a 
Windows 98SE
system with GHOST making the image file of the C: drive.  Each monthly 
was about 950 MB
and 4 * monthly would fit on one DVD-R along with an ASCII text file 
with MD5 values for
each image backup file.  I just copied one of the 2003 backups to a 
current Windows XP
system and checked each of the MD5 values against the known value from 
the ASCII text
file.  ALL MD5 values were the same.  I must thank Tim Shoppa for the 
use of MD5 values
to verify that a file is unchanged.  Also for using bzip2 for 
compression.  For large files that
compress easily, I will save the MD5 value for both the compressed and 
uncompressed
version, but archive only the compressed version on one DVD-R along with 
the file which
holds the MD5 values (I also record the size of the file).

Have I just been lucky?  I plan to make up a few DVD-R media with just 
the December 31st
backup to preserve one backup from the end of each year.  Three DVD-R 
should hold all
of the years along with a few individual files.

Has anyone else found that DVD-R media are satisfactory for 5 years at a 
time?

>The mainframe people use cartridge-loaded WORM media which is 60 GB per cart. I think
>it's magneto-optical but who knows, maybe it's really closer to Blu-Ray type technology. For
>a while (back in the 600 Mbyte/cart era) I was a big fan of the 5.25" magneto optical
>carts but CD-R and DVD-R is so easy that I have a hard time going back.
>  
>
About 15 years ago, I acquired over a hundred magneto optical media for 
the Sony SMO S-501
along with a few drives.  Since they are 295 MB on each side (590 MB per 
media - only one side
available at a time - these are flippies), the DVD-R media at 4.7 GB are 
about 8 times the capacity
and 1/4 the thickness.  So the magneto-optical can't compete with the 
convenience of a DVD-R.

Does anyone have much experience with Blu-Ray reliability.  I really 
need a larger capacity media
when I switch to Windows XP as the monthly backup will likely be around 
8 GB.  Blu-Ray would
also reduce the bitsaver media needed to just TWO.  Incredible.  Also, 
what is the current time
to read and / or write a 25 GB Blu-Ray media?

Jerome Fine



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