Live cache Recovery.....

[Former Member]

Hello all,

This is related to SAP DB version 7.4.3.32 and it is running on Windows. My DBM GUI version is 7.6.00.12. On the recovery tab of the DBM GUI there is a option called "Recovery with Initialization". I have used this option to recover my SAP DB database and it was always successful. I used this option to intialize the existing database with a good full backup. This is a new option in 7.6.00.12 DBM GUI. It was not there in 7.4.3.30 DBM GUI. Though it is not a good option all the time but it is very good if your database is crashed and if you have latest good full backup then you can use this option for recovery.

My question is that I have never tried this option (Recovery with Initialization) on our Live Cache database (SAP DB instance installed as Live Cache on Solaris). I do see this new option in DBM GUI in 7.6.00.12 DBM GUI as DBM GUI is same for both type of database.

Is it possible to use this option for our SCM 4.0 Live Cache in same way I have used it for SAP DB database. It will be a very good option for Live Cache if we have one good backup and Live Cache is crached then we can use the latest full backup to restore the Live cache.

Please let me knwo if anybody knwos about it or have tried it.

I will really appreciate your help.

Thank you.

Sume

[roland_mallmann]

Hi,

it <b>is</b> possible indeed to use the "Recovery with Initialization" routine to recover using a certain full data backup.

Please keep in mind that point-in-time recovery scenarios are <b>not</b> supported, in case you want to do something like that, you should be aware of possible inconsistencies.

In short: you can use it as you did with your OLTP instance.

Please do not use it as a means to initialize your liveCache instance, because that should be done with transaction LC10.

Regards,

Roland

[Former Member]

Thank you for the reply.

No. I am not intended to use this method for Initializing the liveCache. I want to use this method in a case when our LiveCache is crashed or we want to restore the Livecache with earlier backup (not interested in point-in-time).

Lets say that -

<b>First Case -</b>

Today is Jan 1st and I took a full backup.

From Jan 2nd - Jan 6th, more activity took place and increased the size of the livecache.

It <b>crahsed</b> on Jan 7th.

<b>Second Case -</b>

Today is Jan 1st and I took a full backup.

From Jan 2nd - Jan 6th, more activity/testing took place and increased the size of the livecache.

On Jan 7th, the testing was over and management decided to restore with backup of Jan 1st. They were not interested in any data created while testing (log files between Jan 2nd - Jan 6th), which will do the point in time recovery.

I would prefer to use <b>Recovery with Initialization</b> for both the cases. Management agreed that this restore will not have a data created between jan 2nd - Jan 6th (Is this the type of possible inconsistencie you are referring?).

Would you agree with this approach.

I will appreciate your help and advice.

Thank you.

Sume.

[roland_mallmann]

Hi,

with liveCache it's a little bit different as opposed to an OLTP instance. The most imporant difference being that when you're using liveCache, there's <b>always</b> another DB instance aswell, the SCM/APO instance. The consistency between these two instances is of the utmost importance. Therefor, after <b>every</b> recovery of liveCache, you should run certain consistency reports to make sure the data in liveCache and SCM DB are consistent.

A normal liveCache recovery would look like this:

- you've got a (successfully saved) full data backup

- you've got several log backups

Using the above backups, you can minimize the loss of important data when experiencing crashes.

In your <b>first case</b>, you would recover using the last full data backup and could then continue to recover all available logbackups (either manually or automatically created).

> You could do a recovery <b>without</b> initialization here aswell, because all changes should still be on the logvolumes.

In the <b>second case</b>, you would just recover + init the data backup from Jan 1st.

In <b>BOTH cases</b>, you should run the consistency reports afterwards!

Regards,

Roland

[Former Member]

Thank you very much for the reply.

I understood it.

Yes. The consistency check reports should be run afterwards.

Thank you.

Sume