Thursday, 5 February 2015

Most Recently Asked SAP HANA Interview Questions and Answers (Part5)

41. You mean I have to buy a HANA only 2.5x smaller than my big Oracle RDBMS? What about archiving and data ageing?
Yes, in some instances you may have to buy a HANA appliance that is only 2.5x smaller than it would be under Oracle. And data ageing isn't part of the 1.0 release, but SAP is certainly working on it pretty hard. Let's hope they release something faster than you need to buy a bigger HANA appliance!

42. What's the wider market opportunity for IMDB?
This is the interesting thing - no one knows yet, and few analysts seem to have cottoned on that the wider market opportunity might be huge. Think not just SAP applications but any third party that requires ultra-high speed. Think not just an appliance but a development platform. Time will tell.

43. What hardware is supported right now?
Talk to your hardware vendor - all of the major vendors e.g. HP, IBM, Dell, have HANA offerings now. Technically HANA will run on any Intel x64 based system from your laptop through to the big 40-core, 2TB RAM servers. It is however only supported on a small number of big rack-mount servers like the Dell R910 and HP DL980.

44. Why doesn't HANA run on blades?
It's unclear but probably because the blades don't yet offer the same performance. HANA is optimized for the Intel X7560 CPU and will run fastest on this. And for instance, the Dell M910 blade can only run 2x X7650 CPUs and 512 GB RAM in this configuration, which probably explains the limitations. What's certain is that HANA will eventually run on blades - it's born to run on blade technology!

45. Does SAP make their own IMDB/HANA hardware?
Yes, but only in the labs so far. There are no public plans to compete against IBM/HP/Dell in this space, but it may make sense for SAP to enter the appliance market, especially in the context of Data Centres and even more so in the context of the SAP Business by Design cloud offering, which will run on IMDB.

46. How big does HANA scale?
Theoretically at least - very well. The biggest single-server HANA hardware will run most mid-size workloads - 2TB of in-memory storage is equivalent to 5-20TB of Oracle storage. The way that HANA works means that it is possible to chain multiple systems together - meaning that scalability has thus-far been determined by the size of customers' wallets. Do note that whilst SAP talk up "Big Data" quite a lot, HANA currently only scales to the small-end of Big Data, which refers to the kind of huge datasets that Face Book or Google have to store - not Terabytes, but rather Peta bytes.

47. What storage subsystem does HANA use?
 This varies from vendor to vendor but it is shared network attached storage (NAS). Both regular magnetic disks and SSD storage can be used for the backup of the database (HANA runs in memory remember, so disk storage is just for backup, and later, for data ageing). Note that you require 2x storage that you have RAM, which is 2x the database size - i.e. storage size = 4x database size. In most cases there is additional ultra-high speed SSD storage for log files.

48. What source databases does HANA support in real-time?
If you use Sybase Replication Server (SRS) for near real-time data then you need to watch out for licensing still (SAP have license deals pending). If you run DB2 then you're fine but with Oracle and Microsoft SQL Server there are some license challenges if you buy your license through SAP, because you may have a limited license that does not allow extraction. Talk to SAP for further information on this.

49. What source databases does HANA support for batch loads?
If you use SAP Business Objects Data Services 4.0 for bulk loads then pretty much anything. BO-DS is a very flexible Extract, Transform & Load tool that supports many databases - check out the specs for more details.

50. What additional limitations does Sybase Replication Server present?
SRS has additional restrictions which are worth bearing on mind. It can only replicate Unicode data and does not support IBM DB2 compressed tables.
More Questions & Answers :-
Part1  Part2  Part3  Part4  Part5

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