MAXDB High Availability and Failover

[Former Member]

Hi Gurus,

I am architecture and designing the MAXDB 7.6 high availability and failover. The option implementing is "STANDBY DATABASE". Question is "Does MAXDB support Multiple Standby Database". Reason I am asking also plan to setup STANDBY database for Disaster Recovery. That's why trying to find out more information is this feasible or not. If anybody has implemented this scenario, I will appreciate the technicality and the experience on this. Or direct me to the right place to look for the answer.

Thanks for everyone's time.

Saroj

[Former Member · Accepted solution]

Hi Saroj

It would be poosible to have multiple standby databases.

As the process of shipping and applying the log backups to the standby database is a manual process (i.e. no maxdb set of commands to do this for you) , you will just have to modify your scripts to copy the log backups to your various DR instances and apply the log backups to these instances.

Regards

Doug

[Former Member · Accepted solution]

Hi Doug,

Thanks for your response. I went through the MAXDB wiki and found that script to automate log shipping in STANDBY database. Question is in case of Frame crash, won't able to recover log to apply in standby. Is there any solution to prevent the loss of data.

Thanks again for your effort and time.

Saroj

[Former Member · Accepted solution]

Hi Saroj

From memory, the scripts on the wiki only copies the log backups at the end of the day and then applies them.

A better solution is to copy the log backups to the standby server as soon as possible after they have been created. I would also have the auto log backup set to run periodically, how often would depend on your requirements. Without replicating your logfile to your standby system you will always lose this data in a disaster. The amount of time between your log backups will dictate the amount of data you will lose. There are tools that can replicate the log backups and logfile to your standby system in (almost) real-time which will minimise your loss of data.

The impact of the loss of the WAN/LAN connection to your standby system depends on the delay of getting the log backups (and the logfile changes) to your standby system.

Hope this helps.

Doug

[former_member229109 · Accepted solution]

Hello Saroj,

A) If you think about the log area disk error/lost, then the loss of data could occur if you NOT follow the recommendations 3. & 4. < 5. & 6. > from SAP note 869267.

B) As you already know the SAP note 952783 - FAQ: MaxDB high availability, the HA solutions could have the Advantages & Disadvantages.

Please explain in more details, what kind of a disaster you think of?

What you would like to minimize? The system downtime? The data loss?

Then it will be possible to discuss the HA solution for you.

Thank you and best regards, Natalia Khlopina

Edited by: Natalia Khlopina on Feb 3, 2010 5:38 PM

[Former Member · Accepted solution]

First of all thanks to Doug & Natalia for the valuable info.

Here is what exactly looking in terms of MAXDB High Availability and Disaster Recovery.

Instead of Hot standby approach I am going for HA & DR for MaxDB is that STANDBY DATABASE and can have 2 standby databases (One for HA, one for DR). So no concern there

HA failover is manual. From my perspective, manual failover is not providing HA. It will not meet 99.999% or 99.99% availability.

MAXDB STANDBY DATBASE design shows logs being placed in a staging directory. That makes me think there is a shared NFS filesystem between the 2 servers used for log transfer.

The Shared Storage wonu2019t be available in DR until a disaster is declared. Meaning, logs could not be applied from a shared stage directory if it is indeed on NFS

My main concern:

Are there alternative IP-based log transfer methods? If not, a standby may not be appropriate for DR . Note, if canu2019t use a standby for DR, then may not be the right approach.

Will virtual host names be redundant?

Issues here is HA failover need to be automated.

How logs are transferred/applied from one host to another. Shared storage cannot be used as the mechanism for this.

Amount of loss of Data, in case of frame crash.

Sorry for the lengthy message but this is what looking for the MAXDB HA & DR aproach.

Thanks again for all your effort and time. Help will be appreciated.

- Saroj

[Former Member · Accepted solution]

Any advise or suggestions to my previous message. I will really appreciate your help.

- Saroj

[Former Member · Accepted solution]

Hi Saroj

There are a number of vendors that provide products for HA and DR. For example, HP Service Guard, NetApp etc.

You may need a mixture of vendor products to achieve your goals.

As you have defined your requirements for the HA and DR (above), the next phase, for you, is to find out your budget($$$). Then start talking to vendors about your requirements and your budget.

A standby database may not be part of your solution if you choose to replicate the entire database at either the SAN or OS level.

Regards

Doug

[lbreddemann]

Question is: Why is the 'architecture' not able to use the search facility on this site and instead asks other people to do his job?

There are even samples for what you want to do available in the SDN Wiki... but of you're too lazy busy to look for it, you may hire somebody to do the work instead anyhow.

regards,

Lars

[Former Member]

FYI, I always search in GOOGLE and SDN forum before I post message on any forum. That's the thumb rule I follow.

Here are the information which I already looked before I posted this message for your kin information.

http://wiki.sdn.sap.com/wiki/display/MaxDB/HowTo-StandbyDBlog+shipping

http://wiki.sdn.sap.com/wiki/display/MaxDB/SAPMaxDBHowTo

http://wiki.sdn.sap.com/wiki/display/sandbox/ExpertWikiMockup

http://wiki.sdn.sap.com/wiki/display/MaxDB/SAP+MaxDB

http://wiki.sdn.sap.com/wiki/display/MaxDB/SAPMaxDBSupport+Guide

Failover from the primary to the standby database

To perform a switch (or failover) from the primary instance to the standby database, it's necessary that all remaining log entries since the last applied log backup are transfered to the standby database and applied there.

To do so, just create a log backup (which is also possible when the data area is not accessible anymore and the database can only started up to admin state) and make it available on the standby server. After the recovery of this last log backup the standby database can be opened.

Finally the applications that should access the standby database need to have the connection data so that the new server is accessed (e.g. change of hostname and database name).

If the application use the XUSER mechanism to logon to the database, only the XUSER data need to be changed to redirect the application to the standby database.

My question was "whether it's possible or support the multiple MAXDB standby datbase or not. Otherwise I know if I can setup one standby then I can do another one too. Then need to use pipe to do log shipping to synchronize with Primary/Master datbase.

Now come to the second part of your message.

"There are even samples for what you want to do available in the SDN Wiki... but of you're too lazy busy to look for it, you may hire somebody to do the work instead anyhow."

When your are there to do the job, why need to hire somebody.

Usually everybody says increase the knowledge by sharing with others. I am not intruder to your property. This is public forum and not compelling you to answer. If you know you answer and otherwise do not. But by mentioning this you prove yourself what you are.

Have fun with knowledge you have and attitude.

Saroj

[lbreddemann]

>

> FYI, I always search in GOOGLE and SDN forum before I post message on any forum. That's the thumb rule I follow.

Well, the question did not look like you did.

> Here are the information which I already looked before I posted this message for your kin information.

> http://wiki.sdn.sap.com/wiki/display/sandbox/ExpertWikiMockup

You looked up the "Mockup" page ??? really?

To me this looks like you didn't like me answer and now copy/pasted the links you found now.

> My question was "whether it's possible or support the multiple MAXDB standby datbase or not. Otherwise I know if I can setup one standby then I can do another one too. Then need to use pipe to do log shipping to synchronize with Primary/Master datbase.

Pipes ? For a failover scenario? For multiple standby DBs?

You seem to be either very optimistic or have some very robust pipes at hand that are available even in a failover case.

> Now come to the second part of your message.

>

> "There are even samples for what you want to do available in the SDN Wiki... but of you're too lazy busy to look for it, you may hire somebody to do the work instead anyhow."

>

> When your are there to do the job, why need to hire somebody.

> Usually everybody says increase the knowledge by sharing with others. I am not intruder to your property. This is public forum and not compelling you to answer. If you know you answer and otherwise do not. But by mentioning this you prove yourself what you are.

>

> Have fun with knowledge you have and attitude.

Well, besides the fact that some of the Wiki pages (interesting to note that you did not find any of the SAP notes on that topic...) are actually from me (sofar to the sharing with others point) I do take the freedom to write my opinion when somebody seems to ask others to do his homework.

It's up to you whether you like it or not.

(You don't have to, you know)

regards,

Lars

[Former Member]

Thanks for your swift response.

This message actually posted by me and I just did cut & paste from my research note.

I already refer the SAP Note 952783 - FAQ: MaxDB high availability and the attachment "Standby_MaxDB_pdf" file for our failover scenario.

Longstory in short, thanks for your time.

Saroj