Time for LMTS conversion

[Former Member]

Hi Everybody,

The client wishes to perform DMTS -> LMTS conversion. The PRD DB-CI config is as follows:

Server: IBM P570

CPU: 8 * 2 GHz

Memory: 24GB

DB size: 1.5 TB

The client wants time estimates for the following options we presented:

1. Reorganize with BRSPACE / SAPDBA (online)

2. Reorganize with BRSPACE / SAPDBA (offline)

3. Export / Import with SAPINST

Could you please share your real-life experience in this regard?

Also, please let me know the time it took for the LMTS conversion. Please specify, if possible, the H/W, database size & versions worked on.

Thanks.

[former_member204746 · Accepted solution]

it took me weeks!

I reorg'ed every single tablespace online 1 by 1 (except SYSTEM) with SAP note 646681. This does not involve a lot of downtime but it takes a long time (and some additional disk space).

a complete export/import wil ltake a lot of time, so, if you do not have a lot of downtime available, this is not a solution.

please3 read http://bwfreak.com/joomla/index.php?option=com_content&task=view&id=111&Itemid=1 for interesting info.

DO NOT USE dbms_space_admin.Tablespace_Migrate_TO_Local. This is not supported by SAP.

[lbreddemann]

Hi Kailash,

for a estimation of the runtime, you will have to perform the reorg on a comparable machine first.

There are far too many factors that can influence the performance of such a reorg.

Testing the reorg first also brings the advantage of beeing able to tune the process beforehand, since you can check on what resources the involved programs/sessions have to wait the most.

KR Lars

[Former Member]

Hi Eric,

How big was the DB that you reorganized online? Also, what was the machine config?

Did the online reorg affect production operation noticeably?

Regards.

[former_member204746]

DB was 950GB, after complete reorg, It went down to 600GB.

this was on Windows on 4 CPU of 3.4Ghz each.

Reorg did affect the performance of the system. So, I was running those BRSPACE commands nightly when nobody was working on the system. Background jobs were slower but nobody really cared.

The worst part of the reorg is tables that have RAW or LONG RAW filed types. these must be reorganized offline... and they take a lot of time to be reorged. I was able to reorg this kind of tables at a slow rate of 3GB per hour. Really ugly.

[Former Member]

Hi Kaushal,

I've already reviewed note 214995. I'm just looking for time estimates for various database sizes on different platforms & HW configuration.

Regards.

[Former Member]

Hi,

it is difficult to say how much time it's required.

check Note 541538 - FAQ: Reorganizations question 9

regards,

kaushal

[markus_doehr2]

The speed is heavily dependent on the underlying I/O subsystem. You can convert 1 TB in some hours or some days - it all depends on the distribution of the files, SAN cache size and other things. Even having the same OS and database version the differences can be that big because the conversion is mainly driven by I/O speed and what your storage is able to read/write in a certain amount of time.

I would, to get an estimate, convert a tablespace on a test system (as long as the SAN environment is equal) and check how long that takes. You can mix DMTS and LMTS in a database without problems.

Markus

[Former Member]

HI,

read Note 214995 - Oracle locally-managed tablespaces in the SAP environment

regards,

kaushal