W9 - FILE COMPRESSION AND BACKUP

Question 1

W9-1: What is “File Compression?”

Answer 1

_ storing a file’s data in “LESS SPACE” by “MINIMIZING REDUNDANCY” indatacontent
_ An ARCHIVE is a collection of folders and files stored in one file, e.g. filename.ZIP
+ Files are usually compressed (but not necessarily)
_ SSH (Secure SHell) can compress data: asynch.
_ VoIP must do this in real-time, synchronously.

Question 2

W9-2: Why use File Compression?

Answer 2

_ Sending data takes bandwidth and I/O time
+ Tape – not as obsolete as you might think
+ NAS – Network Attached Storage (local or remote intranet)
+ USB – removable drives (ad hoc, user level)
+ FTP or Cloud Storage: AWS Glacier, Google Nearline
_ Encrypt off-site data for security
+ compression software has a password encrypt option

Question 3

W9-3: How File Compression works

Answer 3

Compression combines:
_ MATCHING and REPLACEMENT of DUPLICATE strings w/t pointers.
_ replacing symbols with NEW, weighted symbols based on FREQUENCY of use.

Question 4

W9-4: What is “Lossless” Vs. “Lossy” Compression?

Answer 4

_ Lossless: contains all ORIGINAL data with redundancies removed.

_ Lossy: drops things-you-won’t-notice (you hope) from ORIGINAL data