Making ArchivesThere is limited hard disk space available. Therefore, you have to take less frequently-used files offline. The most convenient medium for long term storage is the optical disk. When you leave this lab. you also want to leave copies of your archives behind, properly indexed. Following are some advice on how to do this properly. |
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| Media |
Recommended
media are CD-R (not RW) with a capacity of 640 to 700 MB and DVD-R (not
DL) with a capacity of 4.7 GB. CD-RW is not recommended because the
recording method is not as robust as CD-R's. Double-layer (DL) DVD-Rs
are not recommended because there are still many drives that cannot
read them. Tapes are not recommended because they are slow. However,
optical disks are not as long lasting as originally thought. Recorded
disks should not be left in hot places, such as a disk drive or a car.
If stored properly, optical disks are thought to last about five years. |
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| Gather |
The most
important step is to gather your files for archiving. Note that binary
files can compress by approximately 10% at best. Text files can benefit
most from compression. Bear this in mind as you gather your files. For
example, if you are archiving mostly text files to a DVD-R, gather up
to 8 to 10 GB of files for each archive. To determine the size of your
collection in kilobytes, type:du -sk
directoryname.If you have a choice, convert binary files to text form for the archive. This will make the archive more useful in the future because you may not have the proper program to read the binary files many years from now. (For YUP users, use Yup.avf.)Make a listing of your files and save it along with the archive: ls -laR
directoryname > catalogfile. |
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| Transfer |
Make a
compressed tar archive of your files, on IRIX:tar -cf - directoryname |
gzip > directory.tgzon other systems: tar
-czf directory.tgz directoryname.These commands use GZIP for compression. If you need even tighter compression, try BZIP2 (not available on IRIX). You will have to make the tar archive first, then compress the archive. This will protect the file formats and case-sensitive files. Optical disks cannot hold case-sensitive files. (I am not aware of any UNIX/LINUX system that can write native files to optical disks.) It is also easier to compress a single file, and to transfer it to another system. Keep the catalog listing separate from the tar archive. Use AppleShare to mount the UNIX volume, then drag the archive and the catalog listing to an empty optical disk. This is faster for the /LNX volume because the traffic is routed internally through the private Gigabit network. If you use SFTP for the transfer, your traffic will run through the public Megabit network. |
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| Archive |
It is easy to burn an optical disk in MacOSX. Make two verified copies, label them (use a pen that uses water-soluble inks). Store the disks in two separate cool, dark and dry places. Make a third copy for the lab. Once you have verified copies, remove the original files from the hard disk. This is important. We will not gain any advantage from your effort unless you reduce your online usage. |
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