Poor VMDK Backup Performance on Full backup

Last post 09-11-2019, 11:48 AM by Nirav kapadia. 2 replies.
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  • Poor VMDK Backup Performance on Full backup
    Posted: 09-10-2019, 10:17 AM

    Hi

    CV11 SP14

    At the weekend I suffered from performance issues

    Normally, I have no issues, but on the weekend concerned I was running Full backups of our VMDK servers, normally we do a Incremental/Synthetic Full and once a month
    run a Full.

    At the same time normal agent backups were running and Synthetic Full (normally these are 2000+ GB/hr, but I was getting as low as 20GB/hr) and their performance was awful, kill the VMDK backups everything back to normal

    I believe my DDB speed is okay at Average Q&I time of 340ms


    This got me thinking about how the deduplication of the backup is configured

    My initial question is my VMDK Backups are configured 'Enable Deduplication' -> Generate Signature on Media Agent

    For my Agent Backups such as File System, I have this set to 'Generate Signature On Client' and I see on the client some CV_CLDB* files

    So, if the signature is being generated on the Media Agent with the VMDK, is this directly with the DDB?

    If I set the VMDK backup to 'Generate Signature On Client', where would it create these signatures, against the proxy?

    Would it actually assist performance?

    Thanks

    Mark

  • Re: Poor VMDK Backup Performance on Full backup
    Posted: 09-11-2019, 11:45 AM

    Generate signature on MA. means we send data over the network to MA and signature get generated on media agent and then compare against DDB which may be on same MA or other MA. 

    Generate signature on client: for VM, the signature get generated on client and then query to DDB on media agent. We dont transfer data over network, just signature which is 8 bytes only. based on the answer from DDB we either send data and signature or only signature

    That being said, for VM if your proxy DDB and data mover MA are same above process happens on same media agent either signature generation is on MA side or on client side.

    backup speed depends on your network transfer but generating signature on clietn side saves on band width as we are transfering only unique data over the network. 

  • Re: Poor VMDK Backup Performance on Full backup
    Posted: 09-11-2019, 11:48 AM

    Generate signature on MA, means we send data over the network to MA and signature get generated on media agent and then compare against DDB which may be on same MA or other MA. 

    Generate signature on client: for VM, the signature get generated on proxy (for other apptype it on client) and then query to DDB on media agent. We dont transfer data over network, just signature which is 8 bytes only. based on the answer from DDB we either send data and signature or only signature

    That being said, for VM if your VM proxy,  DDB MA and data mover MA are same machine then above process happens on same media agent either signature generation is on MA side or on client side.

    backup speed depends on your network transfer, but generating signature on clietn side saves on band width as we are transfering only unique data over the network. 

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