• This topic has 2 replies, 2 voices, and was last updated April 30, 2019 by Babak S.

Journal History function and concept

  • Dear all


    although I was read some documents but actually I am so confused in many parts during wizard configuration for example when I set Journal History = 1 Hours

    Is that means it will keep restore points maximum for one hours ago ?

    actually what happen will be do after 1Hours ?


    While I set Journal Size Hard Limit = 20G and Journal Size warning thresholds = 15G is that means maximum data change for this VGP is 20G ?


    But here I could not understand Limitation for Journal History and the other for Size limitation


    • in my datastore on recovery site created a folder with the name ZeRTO volumes and there is a VMDK fie with name

    785_datastore1 (10)_vm-1752_history_10_10_50_60_log_volume.vmdk

    Is this VMDK file Journal file ?

    What happen will be do if this VMDK file remove ?

    What is the maximum and minimum size of this file ?



    • also in recovery site such as previous VMDK, create other VMDK file with name of replica machine

    for example for me is “IVR-BackUp-new.vmdk” now I want to know what is this file and if I remove that

    what will be happen ?



    • actually I could not understand clearly What does Target RPO Alert mean for example if I set that on 1Min or 20Second

    what is difference?







    Hi Babak,

    Will try to answer as many of these I am able to:

    Q: When I set Journal History = 1 Hours does that means it will keep the restore points maximum for one hour ago? What happens after 1 hour?
    A: Journal history of 1 hour means that Zerto will retain the last hour’s worth of changes as checkpoints.  After an hour has passed, Zerto will phase out the oldest checkpoints and begin replacing them with new ones

    Q: When I set Journal Size Hard Limit = 20G and Journal Size warning thresholds = 15G does that mean that the maximum data change for this VPG is 20G?
    A: We have options for hard and soft limits: by the size of the journal, the percentage of the available datastore (i think) and unlimited.  In the dashboard, you’ll see a compression percentage for the journal.  Let’s take a for example and keep the compression at a constant 50% to make the math easy:

    If you have the hard limit at 20GB, the threshold warning at 15GB, and our 50% compression, then that means Zerto will be able to store 30GB worth of changes before hitting that warning threshold and issuing an alert.  With a 20GB hard limit and 50% compression, you can make 40GB of data changes on the protected VM before Zerto calls the journal full and then starts flushing old data to the replica volume. It doesn’t stop protecting the volume, but it keeps the journal at 40GB so if change rate speeds up on that drive you’ll see the length of the journal go down.

    Q: I could not understand clearly what does Target RPO Alert mean. For example, if I set that for 1 min or 20 seconds. What is the difference?
    A: The Target RPO Alert is the RPO at which Zerto will issue you a warning to state that your VM/application is not meeting its SLA.  With Zerto you can tier your application with different RPOs so they deliver the SLAs that are required for your business.  A Target RPO alert of 20 seconds means that Zerto will alert you when the RPO is has reached 20 seconds. The same goes for a Target RPO alert of 1 minute except the alert will issue when the RPO has reached 60 seconds, not 20.

    Hope this info helps

    so thanks

    i have 3 questions :


    1- in previous posts about Target RPO Alert : for example  set that for 5 min now when i see my restore point its such as below

    its approximate every 5 second now is that mean while duration time between two restore point exceed 5 min will be show a warning ?

    April 30, 2019 12:15:02 PM
    April 30, 2019 12:14:57 PM
    April 30, 2019 12:14:52 PM
    April 30, 2019 12:14:47 PM
    April 30, 2019 12:14:41 PM
    April 30, 2019 12:14:36 PM
    April 30, 2019 12:14:31 PM
    April 30, 2019 12:14:26 PM
    April 30, 2019 12:14:21 PM
    2- In VPG panel such as below show Actual RPO 7 second and it change to 8 second and … what does that means ?
    3- when i start replication job in destination datastore create 2 folder :
    Z-VRA-“esxi host name”
    ZERTO volumes
    which each of them include a VMDK file As i understand one of these vmdk files is exactly such as source vm and the other vmdk just save changes or restore points is that correct ?
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