MCD is a program for storing very large files onto several CDs or DVDs
so that the original data can be reconstructed even if some files
become unreadable in future. The original data can be reconstructed
even after complete loss of one or two CD/DVD disks. MCD is not
a burning program - it can only cut the data into several blocks,
compute horizontal and vertical parity and store the result in
subdirectories. Files from
each subdirectory must be later burned onto a CD/DVD by other tool like
How MCD works
Before burning, the input data is divided into smaller blocks.
Each disk contains up to 64 data blocks and two parity blocks.
The block size is approximately 11 MB for CD and 70 MB
for DVD disks. If there is a problem with reading of one or two
data blocks then the parity blocks can be used to reconstruct the
original data (horizontal parity).
Finally, another one or two disks with vertical parity is added to
the archive. These disks are used if there are more than two unreadable
blocks on any media (or if some media is lost or become completely
If only one vertical parity disk is added then the archive
can survive complete loss of a single disk. If two parity disks are
generated then the archive will survive two lost disks.
The basic block structure of the archive is displayed below. Each
disk contains up to 64 data blocks (for example d01_db02 is second
data block of the first disk). Then two blocks with horizontal
parity are added (d01_pb01 and d01_pb02). The last two disks
contain vertical parity.
One of the most important features of all archiving programs is
compatibility with different computers and future versions of
operating systems. Therefore, to increase chance for succesful
archive restoration, MCD program is distributed together with
full source code. Both program executable and source code is
also copied to every archive. This way, it is possible to extract
the original data even on machines without MCD installed.
If for any reason the current version won't work on future operating
systems then the source code can be modified and the program can
be ported to the new environment.
MCD used for archiving digital video
MCD was originally developed for archiving huge files with digital
video (DV) onto CD-ROMs. One hour of video in DV format has
approximately 13 GB and needs over twenty 700MB CD disks.
When DVD is used then only three media are used for data and one
or two media for vertical parity. Due to much smaller number of
DVD disks it is usually enough to use only single vertical parity
disk. Three DVD disks are exactly enough to store 60 minutes in
DV PAL format. It is good to know such limits already during video
editing because 61 minutes would already need four data DVDs.
MCD was designed exclusively for storing very large files. It is very
inefficient for files smaller than several tens of megabytes. When
higher number of small files must be archived then the files should
be first compressed into single big file.
The program was compiled for Win32 API. It can work with very big
files (over 4 GB) but such files must be stored on a NTFS
partition (operating systems WinNT, Win2000 or WinXP). At the run
needs approximately 50 MB RAM when a CD archive is created
and 250 MB RAM for DVD archive creation. At the same time it
needs free disk space approximately 1.2 - 1.5 times bigger than
the original data.
MCD is freeware (free for any commercial and non-commercial use).
It needs operating system Windows 98 or better. No installation is
- just copy the mcd.exe and mcd_src.rar files into a directory and run
MCD is a console application (no windows or dialogs) and parameters
must be specified at command line.
Download: MCD 3.5
(c) Libor Šindlar,