gamename
Enthusiast
Enthusiast

Linked Clones & Datastores

Hi,

Can linked clones from 1 parent span multiple datastores?  Put another way, can i create 10 linked clones from one parent with 5 linked clones on one datastore, and 5 on another datastore?

TKS,

-T

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3 Replies
elgreco81
Expert
Expert

Hi,

In VMware View it's possible and you have 2 options. View works this way, you will have 1 parent image and linked clones will be created from a "Replica" of that parent image, not from the parent image itself. These are the two options:

1) Create the replica on a separate DStore - Only 1 replica is created even when linked clones are located in several Datastores

2) Do not create the replica on a separate DStore - View Composer will create a replica in each Datastore where linked clones are created

In vSphere I never tried to do it...but I think the same principle should apply but as now "composser" service is running, you should do it manually. Sorry, all I have in a vSphere enviroment would be suggestions but, I found this that could help us with the answer (which seems to be "yes"). This is the "powercli" way to do it...

$mySourceVM = Get-VM -Name MySourceVM1
$myReferenceSnapshot = Get-Snapshot -VM $mySourceVM -Name "InitialState"
$vmhost = Get-VMHost -Name MyVMHost1
$myDatastore = Get-Datastore -Name MyDatastore1
New-VM -VM $mySourceVM -LinkedClone -ReferenceSnapshot $myReferenceSnapshot -ResourcePool $vmhost -Datastore $myDatastore

Creates a linked clone from the specified snapshot of the parent virtual machine. The linked clone is stored to the specified VM host and datastore.

The link to this reference

http://www.vmware.com/support/developer/PowerCLI/PowerCLI51/html/New-VM.html

Hope I helped you.

Best regards,

elgreco81

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gamename
Enthusiast
Enthusiast

Thanks for the quick reply.

Am I right in assuming that "replica" is the same as a "snapshot"?

Assuming that's true, then each datastore would need its own copy of a replica. That replica would then have linked clones chained off of that.

So, what would need to happen is something like:

ds0:parent

ds1:parentSnapshot1 -> (ds1:linkedclone1 ... ds1:linkedCloneN)

ds2:parentSnapshot2 -> (ds2:linkedClone1 ... ds2:linkedCloneN)

where

     "ds" = datastore

All correct?

-T

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elgreco81
Expert
Expert

Hi,

Replica is a full copy of your parent image as far as I know and you'll have one master replica in each datastore where you want to have the Deltas from that replica (unless you want to use a dedicated datastore for you master replica...be cautions about iops calculations in this scenario. There are lots of places in the interenet where you can find info about this sizing).

So...saying "parentsnaphot" is not the best thing to do from my point of view as it would lead to confusion. It's a "replica" and the space it uses is quite different from the one a snapshot would use.

Regards,

elgreco81

Please remember to mark as answered this question if you think it is and to reward the persons who helped you giving them the available points accordingly. IT blog in Spanish - http://chubascos.wordpress.com
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