Grandfather system as I usually see it defined is used for full monthly
backups as grandfather, full weekly backups as father, and daily
"incremental" backups between father backups as son as described below. So
if this is the strategy you are following the yes it makes a difference
which set you restore. The most recent backup would be the last father
backup and then the incremental son backups since that father backup.
Incremental backups backup any changes since the last full backup and the
last incremental backup after that full backup. Differential backups that
are not used in this system backup all changes since last full backup. Glad
to hear you have a backup strategy that worked for you. Most users do no or
little backing up.
Grandfather-Father-Son Method
One of the most commonly used tape rotation schemes is called
Grandfather-Father-Son. This scheme uses three sets of tapes for daily,
weekly and monthly backup sets. To execute the Grandfather-Father-Son
rotation scheme, you will need twelve sets of media. The actual number tapes
required in each media set will vary depending on how much data you need to
backup.
The first set, "Son," represents your daily backups. Assign four tapes as
incremental daily backups and label them "Monday" through "Thursday." These
tapes will be used to perform daily incremental backups and can be reused
weekly on the day that they are labeled.
A second set of up to five weekly tapes, called "Father," is used to perform
full backups on the day in which you do not perform a daily incremental
backup. This media set should be labeled "Week 1" through "Week 5" and can
be reused monthly on the day matching its label.
The final set of three tapes, called "Grandfather," is used to perform full
backups on the last business day of each month and can be reused quarterly.
