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From "ASF GitHub Bot (JIRA)" <>
Subject [jira] [Commented] (CLOUDSTACK-8862) Issuing multiple attach-volume commands simultaneously can be problematic
Date Tue, 21 Feb 2017 04:01:44 GMT


ASF GitHub Bot commented on CLOUDSTACK-8862:

Github user anshul1886 commented on the issue:
    @karuturi @koushik-das @sateesh-chodapuneedi , I had analysed those failures and working
on how to go about those. Issue here is that there are marvin tests which are for something
which was never working. But nobody has reported any bugs for that. 
    When we create VM without starting it(startvm=false), then there are issues. So in this
scenario if we try to attach the uploaded volume then its failing in this PR. But in existing
code it is passing successfully i.e. DB entries are created. Now when we start the VM then
we are doing nothing for uploaded Volume and they always remains in uploaded state and not
attached to VM on hypervisor.
    This marvin test is there for ages but nobody has reported any issue regarding this. So
I am currently analysing how to go about this. Is this even used by Users? Because if they
were using this then somebody should have reported this as this was introduced some five years
back. I am thinking of  simple solution  which would be to inform user that they have to start
vm first (root volume created) before trying to attach volume.

> Issuing multiple attach-volume commands simultaneously can be problematic
> -------------------------------------------------------------------------
>                 Key: CLOUDSTACK-8862
>                 URL:
>             Project: CloudStack
>          Issue Type: Bug
>      Security Level: Public(Anyone can view this level - this is the default.) 
>          Components: Management Server
>    Affects Versions: 4.5.0, 4.5.1, 4.5.2, 4.6.0
>         Environment: N/A
>            Reporter: Mike Tutkowski
>             Fix For: Future
> If a user submits two volumeAttach commands around the same time, the first one can succeed
while the second one can fail and can lead CloudStack to ask the underlying storage plug-in
to remove the volume from a given ACL (but the volume should be in the ACL because the first
attachVolume command succeeded).
> A somewhat similar problem can happen if you submit the second attachVolume command to
another VM in the same cluster.
> Proposed solution:
> A data volume should make use of a new column in the volumes table: attach_state (or
some name like that).
> This column can have five possible values: null (for root disks), detached (default state
for data volumes), attaching, attached, and detaching.
> When an attachVolume command is submitted, the volume should immediately be placed into
the "attaching" state. If a transition to that state is not possible, an exception is thrown
(for example, if you're already in the "attached" state, you can't transition to the "attaching"
> A similar kind of logic already exists for volume snapshots.

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