the effect of Block level Deduplication factor on DASH copies

Last post 01-20-2020, 8:14 PM by Anthony.Hodges. 1 replies.
Sort Posts: Previous Next
  • the effect of Block level Deduplication factor on DASH copies
    Posted: 01-20-2020, 5:11 PM

    The default/recommended block size for deduplicated storage policies is 128KB….except for storage policies “associated with cloud storage libraries,” where the recommended block size is 512KB.

    Accordingly, we have storage policies where the primary copy on a local disk library is configured with a deduplication policy block size of 128KB and a secondary copy on cloud storage with a deduplication policy block size of 512KB.

    But when I think about Aux copies, it seems to me that different block size will force all data to be transmitted, and new deduplication signatures generated for all data copied to the secondary cloud storage copy.   Two different sized blocks will neve have the same deduplication signature.    And so to be able to use DASH copies effectively, the primary and secondary copies must have deduplication policies with the same block size.

    Does this make sense, or am I missing something?

  • Re: the effect of Block level Deduplication factor on DASH copies
    Posted: 01-20-2020, 8:14 PM

    Hi CarlosG,

    For differing block sizes, Commvault recommend using the Network Optimized and not Disk Optimized DASH.  For network optimized the data is read on the 128kB side and a 64B signature is generated based on the destination 512kB block size.  This does incur a bit of a read penalty on the source side as this process involves rehydration.

The content of the forums, threads and posts reflects the thoughts and opinions of each author, and does not represent the thoughts, opinions, plans or strategies of Commvault Systems, Inc. ("Commvault") and Commvault undertakes no obligation to update, correct or modify any statements made in this forum. Any and all third party links, statements, comments, or feedback posted to, or otherwise provided by this forum, thread or post are not affiliated with, nor endorsed by, Commvault.
Commvault, Commvault and logo, the “CV” logo, Commvault Systems, Solving Forward, SIM, Singular Information Management, Simpana, Commvault Galaxy, Unified Data Management, QiNetix, Quick Recovery, QR, CommNet, GridStor, Vault Tracker, InnerVault, QuickSnap, QSnap, Recovery Director, CommServe, CommCell, SnapProtect, ROMS, and CommValue, are trademarks or registered trademarks of Commvault Systems, Inc. All other third party brands, products, service names, trademarks, or registered service marks are the property of and used to identify the products or services of their respective owners. All specifications are subject to change without notice.
Copyright © 2020 Commvault | All Rights Reserved. | Legal | Privacy Policy