Guys,
Need your expertise on the definition of
inremental/full/differential backups.
AFAIK based on docs found on the net
Full = Makes a mirror copy of the full tree onto a backup medium.
backs up everything irregardless of whether it has changed
or otherwise
To Restore = Restores the backup medium onto the original tree,
overwriting the original source.
^^ This I understand fully.
Differential = Starts with Full backup, 1st day, finds the
difference with the full backup and backs that up(only
the
bits that changed will be backed up). 2nd day, find diff
betw full backup and 2nd day and backs it up (Incl the
stuffs backed up on the 1st day) etc.. till end of cycle and then
you do a full backup again
Restore = Take the Full backup and restore it. Then take the last day of
diff backup in the cycle before lets say your HD Crashed and
restore
it against the full backup.
^^ This I quite Understand. Each backup is a diff against the source. Sort
of like the kernel patches to the kernel source tree. Eg : 2.4.21 tree
patched by patch-2.4.22
Incremental = Full Backup, Each day will see me backing up what changed
from the day Before. eg : Day1=Full Day2=diff betw
Day2&Day1
Day3=Diff betw Day3&Day2
To Restore = Restore full backup. Take Day2 diffs, diff it against the
full backup. Then take Day3 diff, & diff against the full
backup.. so on so forth.
^^This is a Pain to restore I think.
What I do currently:
Solution 1:
Mirrordir. (HD to HD within Same server)
I use mirrordir to mirror the entire source tree (say [hda]/usr) into say
/mnt/hdb. I keep it rotating for 5days. So.. I think this is essentially a
_full_ backup. (am I right) To restore, I just mirrordir the backed-up into
the source (eg : /mnt/hdb/backupday2 -> [hda]/usr)
Solution 2:
Rsync ( HD to HD to Diff server)
I run Rsyncd on source PC. Shares out the data I wish to backup (eg: WWW,
UserHome, Project etc..)
I run rsync client from backup PC and syncs the files from source to backup
PC. rotating 7 days.
So.. The question is.. (I have not - touch wood - suffered any serious file
loss/HD damage) but am just wondering :
1. What sort of backups am I running? Incremental? Full? Differential?
I think Mirrordir is Full backup.
Rsync?? Is that Incremental or Diff??
I currently restore files by just copying the needed files back into the
source tree. I don't have to do the -restore full backup-diff day2-diff day3
etc..
huh?? Help??!! Explain...
Cheers, .^.
Mun Heng, Ow /V\
H/M Engineering /( )\
Western Digital M'sia ^^-^^
DID : 03-7870 5168 The Linux Advocate
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