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BIA recovery path for scenario not containing a backup

Hi, we are running a small BIA enviroment; 5 blades, 1 is a backup blade.

Environment is stable, it is running on revision 48.

We recently moved from having 2 backup blades to 1, by switching a backup blade to a master. This was necessary as we were running out of capacity.

Next step would be to trade in the last backup blade to a master; and add extra blades to appoint as backups.

Question is. In the case of having no backup blades; and one blade fails. What is required to get all the indexes in memory with the remaining blades (so -1). I understand that having less blades will result in performance loss; but I want to understand what the recovery path is.

Edited by: Paul Bartholomeusz on Jul 28, 2009 8:56 AM

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2 Answers

  • Posted on Jul 28, 2009 at 07:18 AM

    Hi Paul,

    If you have no backup blade and the indizes are splitted over all your blades and one of your server fails than you must reindexing with your remaining blades to get back to normal operation.

    But why you don´t run backup mode mutual? Ok SAP don´t recommend this backup mode because in some few cases you will get problems, but we run it since 1 year and I tested it with some cases and it works without problems (Rev. 49).

    What for a memory consumption have your blades? over 50%? The performance loss depends on your current memory consumption. Please read [this thread for information about memory usage for BIA|;.

    Best regards,

    Jens

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  • author's profile photo Former Member
    Former Member
    Posted on Aug 01, 2009 at 03:15 AM

    Hi Paul,

    You have to pay SAP for the software license for each active blade(non-backup, non-production). So I recommend you to check you licence agreement before you make such decision. If money is not an issue for you and since you have a relatively small environment, in my personal opinion having no back-up blade should be ok. Find out how many times a month you have a blade failure, and how many times the back-up blade picked it. First of all I would go to version 50 -or 52? - then maybe try for a month w/o backup blade. If a blade fails and don't have a back-up blade, you just need to restart the services or bounce the blades.

    Cheers

    Tansu

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    • Hi Elena,

      why you want to switch on the backup blade to master? what do you mean with 'we were running out of capacity.' ? Is your memory consumption over 50% or is the CPU on the maximum?

      Reorganisation:

      The indices are splitted/shared over your blades as kind of blocks and if you run process chains which loading or deleting data your index grows or become smaller, so also this blocks are growing or becoming smaller. The effect is that every blade had another load. A reorg switch this blocks from blade to blade to get the same load for every blade (Good to see with the python standalone tool TREXAdmin.sh on your OS: Landscape: Reorg ->Interactive reorg)

      In my opinion you should do a reorg every day when no load is on the blades. How often you should do this depends on your load, keep an eye on these 😉

      Reindexing:

      All of your loaded indices are loaded into memory, this is the reason why BIA is so fast. If you trigger a reindexing all of your indices on BIA will be deleted and reloaded from DB. In your environment such a reindexing will take about 30-40 min (if you have 16GB Blades).

      May be [this interesting blog|https://www.sdn.sap.com/irj/scn/weblogs?blog=/pub/wlg/9908] [original link is broken] [original link is broken] [original link is broken]; can help you.

      Part IV: BIA Monitoring and Maintenance:

      (...)

      Once you have your indexes built in your BI Accelerator, overtime it can happen that the indexes become larger than fact table in your BI system; this can be caused either by compression in your BI system or by the deletion of requests. We recommend that you execute the BI and BIA table comparison job in RSRV on a periodic basis, and when there is a significant deviation, greater than 50% it is time to rebuild your index.

      (...)

      If you donu00B4t want to buy a new blade but get in trouble with your performance/capacity I recommend to take on backup mode mutual.

      Regards,

      Jens

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