12 Mar
2011
12 Mar
'11
9:22 p.m.
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.
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