[jira] [Commented] (CLOUDSTACK-6369) Qcow2's cluster_size option support

["Marcus Sorensen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CLOUDSTACK-6369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13964662#comment-13964662 ] 

Marcus Sorensen commented on CLOUDSTACK-6369:
---------------------------------------------

Is this something that has a downside to tuning as a general case?  I'm just wondering if it can just be added as a blanket qemu parameter for qcow2 files created a backing file, rather than an end-user exposed tunable.

> Qcow2's cluster_size option support
> -----------------------------------
>
>                 Key: CLOUDSTACK-6369
>                 URL: https://issues.apache.org/jira/browse/CLOUDSTACK-6369
>             Project: CloudStack
>          Issue Type: Improvement
>      Security Level: Public(Anyone can view this level - this is the default.) 
>          Components: KVM
>            Reporter: Yoshikazu Nojima
>            Assignee: Yoshikazu Nojima
>            Priority: Minor
>             Fix For: Future
>
>
> To improve the qcow2 performance, it is important to tune parameters of "qemu-img create" command.
> preallocation=metadata option, which I am working on in CLOUDSTACK-6191 improves randam IOPS well, but the qcow2 image created with preallocation=metadata option cannot be used as a differential image. 
> This "cluster_size" option improves IOPS of a differential qcow2 image which is created with preallocation=off.



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