Difference between automatic and Auto-resize tablespace
Justin
What is the difference between automatic and DMS Auto-resize
tablespace?
Ian
> What is the difference between automatic and DMS Auto-resize
> tablespace?
If you mean automatic storage vs auto-resize:
With Automatic Storage, you assign a series of storage paths to
the database, and when you create a tablespace DB2 chooses where
to put the tablespace containers. So, your create tablespace
command can be as simple as,
"create tablespace myts"
Adding more storage to the database is as simple as a simple
"alter database" command; automatic storage also makes a
redirected restore far simpler.
With DMS tablespaces that use auto-resize, you still need to
specify the tablespace containers on a tablespace by tablespace
basis. However, auto-resize will allow the tablespace containers
to grow (as necessary) without returning a tablespace full error.
FYI: automatic storage uses DMS File with auto-resize for (regular
and large tablespaces) and SMS (temporary tablespaces) under the covers.
Mark A
news:R0mmk.6836$3l5....@newsfe06.iad...
> Adding more storage to the database is as simple as a simple
> "alter database" command; automatic storage also makes a
> redirected restore far simpler.
Except that it appears to me (unless I am mistaken) that if you have a
backup on a database with automatic storage, you cannot switch to a
redirected restore where you specify the paths and containers yourself (the
target database must also use automatic storage). This can create some
problems in certain situations.
Ian
When you restore a database with automatic storage, you can specify
new paths in the restore database command. Example:
create database x on /storage/path/1, /storage/path/2
backup database x to /tmp
restore database x from /tmp on /storage/path/3,
/storage/path/4,
/storage/path/5
This is the equivalent of redirected restore. One command, regardless
of how many tablespaces you have.
Granted, you have less control than with traditional tablespaces. But
in many situations it can be very helpful.
Mark A
> When you restore a database with automatic storage, you can specify
> new paths in the restore database command. Example:
>
> create database x on /storage/path/1, /storage/path/2
> backup database x to /tmp
> restore database x from /tmp on /storage/path/3,
> /storage/path/4,
> /storage/path/5
>
> This is the equivalent of redirected restore. One command, regardless
> of how many tablespaces you have.
Nope, not the same. In many cases I might want to use automatic storage in
development environments (or someone gives me a database with automatic
storage), but I need regular containers in the performance, QA, or
production environments. Of maybe I need to recover a database where I have
to specify the containers in order to make it fit in the space I have
available.
> Granted, you have less control than with traditional tablespaces. But
> in many situations it can be very helpful.
I am not complaining about automatic storage. Very nice. But I would like to
be able to convert automatic storage to regular containers with a redirected
restore (so long as I don't try and convert DMS to SMS or SMS to DMS). It is
not automatic storage that prevents this, it is the way the restore command
works that prevents it. It can be done if IBM wanted to do it. And I was
just warning people that they need to think very carefully about using it,
because it cannot be easily undone.