Chunk and Block Size for Cloud Libraries

  • 2 March 2022
  • 3 replies

Badge +4

Hello all,

I am trying to find some specific guidelines for Block and Chunk settings when related to Cloud Storage.  The information I have found is generally related to Disk and Tape Media.

I have been reviewing an environment that uses Chunk settings of either ‘Application setting’ for Primary Copy and a mixture of ‘Application copy’ and 4096 for secondary copies.

Block size has been set to 1024 and in other cases set to ‘use media type setting’.

I am wondering what the best practices for these settings are and if any of these user set settings are overridden?


Best answer by jgeorges 2 March 2022, 06:32

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3 replies

Userlevel 6
Badge +15

Hi @G.lee 

I’m not a storage expert but this link is for an article titled ‘cloud storage building block guide’ --

Have you seen this article by any chance? if not, please review and let me know if your questions are not answered.



Badge +4

Hi Chris,

Thanks for the response.  I have seen that article.

The Block and chunk settings I reference are in the Data Path settings of a GDDB Primary Copy.  The link details with reference to tape and disk libraries but nothing specific to Cloud.


Any pointers would be greatly appreciated.



Userlevel 5
Badge +9

Hi @G.lee 


Default chunk sizes are covered below:

These are designed for a balance between performance during write and recoverability.

For Cloud storage, theres no need to modify block size to storage. The writes are wrapped up in HTTP Calls as Puts and Gets so block size does not carry across.

However we do recommend Deduplication Block size of 512kb for cloud UNLESS the source is a deduplicated copy, in which case we recommend matching the deduplication block size of the source (by default disk is 128kb).