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We have some Analysis Services tabular (1600) cubes and I know that normally, the data is all stored in memory, but what I can't find the answer to, is what happens to all this data when the server is re-started ? It would appear that there are a load of files on disk for each cube, but it's not entirely obvious what they are. Is that the data as well ?

I know that if you detach an Analysis Service tabular cube and then re-attach it, the data is still there (I don't have to re-process the partitions) so it would suggest that the data is also stored on disk in these files but I can't find anything on the web to prove/disprove this theory, one way or the other.

Does anyone have any ideas ?

Thanks

Dave Evans
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1 Answers1

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Yes, data is indeed stored on the disk. Data is simultaneously loaded to memory and stored on disk whenever the model is being processed. When detaching a model, you're simply removing it from memory, keeping the data on disk only. Subsequently attaching a model (or restarting the server), will then load the data from disk into memory.

Data is also compressed on the disk, so the size of the folder where the data is stored, is more or less comparable to the size of the processed model in memory.

Look in your server properties to locate the folder where data is stored:

enter image description here

Dan
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  • Hi Dan, That's really helpful. Just one more question - is it encrypted in any way ? (one of our clients likes to have their data encrypted as rest). – Dave Evans Jun 14 '18 at 14:05
  • The data is stored on disk using the proprietary VertiPaq compression, but I don't think there's any kind of encryption going on (although for an attacker to be able to read the data, they would need to manually decompress it, which I think is impossible without the proprietary algorithms). My recommendation for your client would be to use BitLocker on the drive where the data is stored. – Dan Jun 15 '18 at 14:35