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Exam 70-768 topic 1 question 3 discussion

Actual exam question from Microsoft's 70-768

Question #: 3
Topic #: 1

Note: This question is part of a series of questions that present the same scenario. Each question in the series contains a unique solution. Determine whether the solution meets the stated goals.
You deploy a tabular data model to an instance of Microsoft SQL Server Analysis Services (SSAS). The model uses an in-memory cache to store and query data.
The data set is already the same size as the available RAM on the server. Data volumes are likely to continue to increase rapidly.
Your data model contains multiple calculated tables.
The data model must begin processing each day at 2:00 and processing should be complete by 4:00 the same day. You observe that the data processing operation often does not complete before 7:00. This is adversely affecting team members.
You need to improve the performance.
Solution: Enable Buffer Cache Extensions.
Does the solution meet the goal?

A. Yes
B. No

Show Suggested Answer

Suggested Answer: B 🗳️
In this scenario we would need both Buffer Cache Extensions and SSD.
The buffer pool extension provides the seamless integration of a nonvolatile random access memory (that is, solid-state drive) extension to the Database Engine buffer pool to significantly improve I/O throughput.
References:https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/buffer-pool-extension

by vstrien at Dec. 4, 2019, 7:58 a.m.

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DudeHere

4 years, 5 months ago

I don't think it's possible to enable Buffer Pool Extensions on an SSAS Only Instance. You tell me what happens when you run this on an SSAS Intance: USE master GO ALTER SERVER CONFIGURATION SET BUFFER POOL EXTENSION ON (FILENAME = 'P:\BUFFER POOL EXTENSION\SQLServerCache.BUFFER POOL EXTENSION', SIZE = 32 GB); GO LOL

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othman_ee

4 years, 6 months ago

Going with B

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clement_

4 years, 7 months ago

In my world "enabling" something does not mean putting hardware on the line. No is my answer since "in combination with a SSD" is missing in the solution.

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panal

4 years, 7 months ago

I think Answer is A (YES), according to https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/buffer-pool-extension?view=sql-server-ver15

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Cococo

4 years, 8 months ago

"Enable Buffer Cache Extensions" implies Extensions, which are SSD usually, the answer is YES

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melvin9900

4 years, 8 months ago

Seems like answer is NO : Need both Buffer pool and SSD Buffer Pool extension file can only keep data pages. There are many other memory sub-regions in SQL Server Memory and this feature can’t cater those. For example, the memory region which has cached query plans can’t be dumped to buffer pool extension file as it can contain only data pages. Also it should be noted that we will not see improvement in performance if the BPE file is kept on spinning media disks. It is recommended to should use SSDs. So you need to evaluate the cost of adding new SSD just to use this feature vs adding more RAM on the server. If you already have SSDs on the server then you can experiment with the feature and check if there is any improvement in the performance

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Jrestrepo

5 years ago

I think the answer should be "Yes", as long as the buffer pool extension is tested thoroughly before implementing in a production environment. Once in production, avoid making configuration changes to the file or turning the feature off. These activities may have a negative impact on server performance because the buffer pool is significantly reduced in size when the feature is disabled. When disabled, the memory used to support the feature is not reclaimed until the instance of SQL Server is restarted. However, if the feature is re-enabled, the memory will be reused without restarting the instance.

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vstrien

5 years, 6 months ago

Buffer Cache Extensions do not exist. SQL Server has Buffer *Pool* extensions, but those are a setting for the relational database engine (extending things to SSD's and alike) - still, this won't help you with an SSAS model that's beyond memory limits.

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Jrestrepo

5 years ago

What do you mean by, "Buffer Cache Extensions do not exits". According to the content of the link provided Buffer pool is also called buffer cache, these two terms are used interchangeable.

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Anette

4 years, 11 months ago

Buffer Cache Extensions and Buffer Pool Extensions is the same thing.

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eceb

4 years, 9 months ago

So, the answer 'No' is correct??

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