snapshot database using db2inidb 
Author Message
 snapshot database using db2inidb

Hi,

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



Sun, 08 Aug 2004 05:42:22 GMT
 snapshot database using db2inidb

Quote:

> Hi,

> 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

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



Sun, 08 Aug 2004 18:52:42 GMT
 snapshot database using db2inidb



Quote:
> > Hi,

> > we are currently evalutating the process for mirroring a database using

"write suspend/resume"
Quote:
> > and mirroring the database files (SMS) with  flashcopy/snapshot technic

of the raid subsystem.
Quote:

> > In the fixpack docu i found a comment that  using db2inidb with the

snapshot option will
Quote:
> > 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

Quote:
> > for customization for this metrics.

> > Thanks
> > Thomas

> 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

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



Thu, 12 Aug 2004 15:48:08 GMT
 snapshot database using db2inidb


Quote:





> > > Hi,

> > > 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

> > 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

> 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

Correction:
A database backup can be taken from this clone database regardless it
contains SMS or DMS tablespace.

Shahed Quazi



Thu, 12 Aug 2004 16:05:13 GMT
 
 [ 4 post ] 

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