snapshot database using db2inidb
Thomas Froelich
we are currently evalutating the process for mirroring a database using "write suspend/resume"
and mirroring the database files (SMS) with flashcopy/snapshot technic of the raid subsystem.
In the fixpack docu i found a comment that using db2inidb with the snapshot option will
result in a "read only" database! Has anyone used this option? Is it really a
R/O database. We plan to use this "mirror" as a analytical database, where different
statistical scenarios will be run using different metrics. So we need updating some tables
for customization for this metrics.
Thanks
Thomas
Bernard Dhooghe
When db2inidb was introduced in DB2 I started to investigate it on AIX
but stranded. 1. My usage resulted in APAR IY16529 (fixed in Fixpack
3) 2. It seemed that it was related to SMS tablespaces 3. Asked for
better explanation of the capability and stopped in the meantime (up
to now).
Even with fixpack info and the manual, even with the manual Data
Recovery and High Availability Guide and Reference lanual,
documentation remains very obscure (SMS and DMS supported?) and the
read-only state is part of it. I'm curious to see other postings.
A number of users (and I implemented it also) take logs from a main
system and replay the logs on another system (as tablespace definition
changes could be in the logs, replay of the logs can not be done on
the same system). But the database remains in rollforward pending, the
notion read-only does not exist here, I find this very unfortunate and
missing in the design. I wonder if splitting of the database could
alleviate this limitation.
Bernard Dhooghe
Shahed Quazi
"Bernard Dhooghe" <no...@attglobal.net> wrote in message
news:25959da8.02022...@posting.google.com...
The snapshot option supports split mirror of both SMS and DMS tablespaces.
Once the split mirror is initialized with the snapshot option it will become
a fully functional database (NOT read-only). The snapshot option of the
"db2inidb" tool is used to create a clone database. It forces the split
mirror database to go through a crash recovery and starts a new log chain.
Therefore, this clone database will not be able to replay any future log
files from the source database. If the database contains DMS only
tablespaces, a database backup can be taken from this clone database and it
can be restored to the source database. However, it will not be able to
rollforward through any log records generated on the source database after
the database was split. Thus it will be a version level copy only.
In snapshot scenario, the split mirror of a database includes the entire
contents of the database directory, all the
tablespace containers, the local database directory and the active log
directory if it does not reside on the database directory.
Shahed Quazi
Shahed Quazi
"Shahed Quazi" <sha...@ca.ibm.com> wrote in message
news:a5a5ru$ah0$1...@tornews.torolab.ibm.com...
Correction:
A database backup can be taken from this clone database regardless it
contains SMS or DMS tablespace.
Shahed Quazi