From: Jolet, John (John.Jolet@MISYSHEALTHCARE.COM)
Date: Wed Oct 16 2002 - 13:43:54 EDT
um, no. the log gets rolled back or replayed when you boot after a system
failure. I don't think you want to mess with them yourself. And bear in
mind that jfs doesn't log the data, just the metadata.
-----Original Message-----
From: justin.bleistein@SUNGARD.COM [mailto:justin.bleistein@SUNGARD.COM]
Sent: Wednesday, October 16, 2002 12:19 PM
To: aix-l@Princeton.EDU
Subject: aix jfslog explanation please
I'm a bit of an Oracle database beginner DBA and from what I
understand from reading from books and doing exercises on my mock database
is that the definition of a log, is when a transaction is made it's not
committed it can always be rolled back. So If I don't have Oracle:
"autocommit" turned on then I use the "insert data" command to insert data
a column into a table, if I then type in rollback;. then the logs will
replay the way that table looked before that column was inserted with the
"insert data" was issued so the column isn't there. OK? Now that knowledge
is out of the way I'm looking at AIX the same way it has a JFS log. Now
from what I understand it holds all filesystem transaction changes. If this
is true, Is it possible for me to roll it back like with a replay or
rollback command just like in a database such as Oracle?. If so would a
good sinerio to use this be when you create a file you don't want you can
replay the log to replay the way it looked without that file?. If so what
are the commands to manage JFS and recreate the filesystems using the log.
For DR it would be a great tool to be able to just replay the JFS logs, to
rebuild them the way they looked in Production. I'm pretty sure mksysb and
sysback actually replays the JFS logs to recreate there Fs's during a
restore. What's the command? Can this be done from the command line, or is
this just an operating system thing?. Also this would be good for tuning
TSM to be an actual BMR solution to have scripts which replay JFS logs. In
Oracle you as the DBA have complete control as too replaying the logs to
recover from unwanted data. Do you have that same control as an AIX ADMIN
to recover from FS's oopss, or recreations in DR? Thanks and sorry for the
novel.
--Justin
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