"Prem K Mehrotra" <pr**********@hotmail.com> wrote in message
news:43**************************@posting.google.c om...
I come from Oracle background. In Oracle, when one wants to do a point
in time
recovery, one can specify recover database until timestmap. Oracle's
database maps to a db2 subsystem, i.e., in Oracle database means
entire database, i.e.. all tablespaces (including indexes).
I see only recover tablespace and recover indexspace (or index)
commands in db2.
Therefore, one has to specify all the tablespaces and indexspaces and
recover them
to a spaecific rba (is that right).
I did not see a recover database command in db2. That can be quite
useful.
My db2 subsystem runs 24x7. Db2 provides a quiesce command to make
various tablespaces consistent to a point in time. Why do I need this
command, if database is 24x7 and I will be always backing up using
shrlevel change.
I am new to db2, so please pardon if I am asking some nnewbie
questions ...
Thanks.
When you speak about DB2 you ALWAYS need to specify what platform (OS) you
are on. You are obviously on OS/390 or z/OS, since DB2 for Linux, Unix, and
Windows allows backup and restore at the database level just like Oracle.
DB2 for OS/390 does not allow recovery (restore) at the sub-system level.
The reason for this has to do with the nature of the mainframe vs. smaller
platforms, where there is often one (or a few) production DB2 sub-system
that is shared by all applications. On Linux, Unix, and Windows platforms,
it is often the case that one application has it owns database server or at
least its own sub-system (database).
You do not have to specify RBA. You can just say "recover" and DB2 will
apply the last image copy and roll the logs the forward to the current time.
Recovering to an RBA is fairly unusual. Most people just "Recover" (to
current point in time) or recovery to a (image) copy.
Quiece has some other features such as taking a synchpoint on the log. This
makes it a bit quicker to recover if there are no changes to the database
(or few changes) between the time you do the quiece and the backup. As you
mentioned, it also helps if you need to recover to an RBA.