cancel
Showing results for 
Search instead for 
Did you mean: 

Shadow System Advice

former_member346857
Participant
0 Kudos

Hi all,

I have started looking into ways on minimizing downtime and came across "shadow systems" I was wondering if anybody has had any experience with this and could give me any advice, comments on shadow systems things like if this is a good road to take, if it is problematic etc? I run our system on Windows 2003 x64 connected to a SAN.

Thanks in advance any input would be welcome.

Jay

Accepted Solutions (1)

Accepted Solutions (1)

Former Member
0 Kudos

Hi,

As juan said Shadow system concept was invented by SAP to reduce the downtime while doing the upgrade. i am not sure that what you are doing in your system but as far as i know shadow systems will be used for the upgrade only not for any installations.

While doing upgrade we have to stratagies 1) downtime minimized

2) resource minimized.

if you select down time minimized strategy for the upgrade then the shadow system will takes the major lead. i mean to reduce the down time of the upgrade, the upgrade will install new instance in your target system that will called shadow, its a logical area. the data and all the tables will be copied from the originial system to the sadow system and the upgrade will runs in shadow only till Modprof_trans phase .

the advantage of this shadow is till the Modprof_trans (Downtime) phase the production operation will be continued.the upgrade will not disturb the production operation because every thing will be done in shadow only even the modification for the dictionary object SPDD will takes place in shadow system only.

once the system reached to Modprof_trans then the upgrade will bring the system down and the data switch will takes place from shadow system to original system in different phases like EU_SWITCH,PARCONV_UPG etc.... so finally the concept is very clear because of the shadow system the down time will be reduced.

Note: while donig PREPARE the system will ask your inputs for the shadow system.

you have to create one service in /etc/services file and you have to use separate host name and the instance no for the shadow, with the above inputs it will create shadow. to perform the SPDD

you need to login in to shadow only with DDIC user in client 000.

if you require more information then have a look in upgrade guide.

https://service.sap.com/instguides

Hope the above information will be helpful for you.

-Srini

Answers (5)

Answers (5)

former_member346857
Participant
0 Kudos

Hi Guys,

Thanks for the info, I now know that I should look into HA systems and not shadow systems, the documentation I read on shadow systems was including downtime for updates and not just upgrades.

Thanks for your help

Jay

sunny_pahuja2
Active Contributor
0 Kudos

> I have started looking into ways on minimizing downtime and came across "shadow systems" I was wondering if anybody has had any experience with this and could give me any advice, comments on shadow systems things like if this is a good road to take, if it is problematic etc? I run our system on Windows 2003 x64 connected to a SAN.

>

What does mean looking to minimize downtime ?

If you are talking in context to upgrade then depends upon 2 strategy ..

1) Downtime Minimized- This is preferred as system is in operation mode for more time and less downtime is required...

2) Resource Minimized- In this more downtime is required...

For more information you can visit market place...

Thanks

Sunny

Former Member
0 Kudos

Hi,

For the minimised downtime you had heard is about the Upgrade. During the upgrade that may be Sap upgrade from one version to another or EHP support pack upgrade Sap used the down time Stratgry.To minimise the downtime sap upgrade(sapup) creates the shadow instance and all the tables and the stracture are imported in the shadow Instance and the shadow instance is upgraded first when this goes successfully then the SAPUP ask to bring the main instance down and copy the shadow instance.

For reducing the down time during the Hardware failure or disater ,we use HA installation.You plann according ly where to have the Central instance and where to have the database as per the stratgy.

Thanks

Rishi Abrol

JPReyes
Active Contributor
0 Kudos

As fas as I know "shadow system" is only used during a system upgrade to minimize the downtime required.

Regards

Juan

Former Member
0 Kudos

Hello Jay,

For minimizing downtime best way is to install High Availability Sytems(HA)..That's the best..