Norbert Martin wrote:
Thats very easy.
Incremental, on default, is: The last active Backup Version of a Backup.
That true if you want to restore the last
incremental 1,2,3,4,5...+ Full Backup state of your server.
By using incrbydate, you can select the backups by date, for sample befor 30
days. All modification on a certain day.
hope this helps
regards norbert
P.S: It's not nice to know who writes
-----Urspr|ngliche Nachricht-----
Von: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]Im Auftrag von
Fc-Atm-Rck, Tivoli (UNKNOWN)
Gesendet: Friday, August 09, 2002 12:28 AM
An: ADSM-L AT VM.MARIST DOT EDU
Betreff: incremental and incremental -incrbydate
What exactly is the different between running backups with incremental and
incremental -incrbydate?
Thank you.
Norbert and who ever posted the original question,
I am sorry Norbert but your explanation of incrbydate is horribly
wrong. In fact you definition of incremental isn't even right.
When TSM does a incremental backup it selects files based on then being
either a new or changed file. This is relative to the information that
is kept in the TSM data base versus what is actually on the clients
machine. Now there are several parameters which determine whether a
file has changed, i.e. data modified, permissions changed, ownership
changed, etc. We also note when a file has been deleted during this
process as well. This is the preferred method for doing your regularly
scheduled backups. In addition Norbert, in you explanation refer to
"incremental 1,2,3,4,5...+ Full Backup", TSM does nothing of the sort!
The old expression for how TSM did backups was "incremental forever",
however that is not in fact accurate either the preferred terminology
today is "Progressive Backup Methodology". We truly do not do full and
incrementals in the classic sense at all!
Now in regards to incrbydate, that is effectively a very limited version
of a incremental backup. It's only advantage is that it will reduce
that backup time for the client, but it does come at a cost. It uses a
reduced set of criteria to determine whether a file gets backed up. The
only criteria it uses is the files data modification time stamp
(remember on some OS's there are multiple time stamps for a file). It
compares this time stamp to a time stamp kept in the TSM DB for the
particular file space that the file resides in. The file space time
stamped is set every time you do a complete ( as opposed to a partial
using a filespec, i.e. Incremental /home/mark/*, when the filespace is
/home) incremental backup. Another unfortunate side effect of the
incrbydate option is that it does not note deleted files. In addition,
a new file moved into the filespace but having a modification time stamp
earlier then the last complete incremental backup will not be backed
up. Another side effect is if you attempt to do a point in time (PIT)
restore it will always roll back in time to the previous complete
incremental.
BTW, include/exclude lists get processed exactly the same for either
command.
The long and short of it, incrbydate should only be used if your backup
window does not allow you to do a regular complete incremental backup.
However if you choose to use this option you MUST still do regular
complete incrementals on some regular schedule.
Norbert, I do not mean to flame in you in any way with this note and I
apologize if you are offended by this. I am sure you did not intend to
be misleading, but I could not let this misinformation go uncorrected.
--
Regards,
Mark D. Rodriguez
President MDR Consulting, Inc.
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