Storage Motion

sara2000
sara2000 used Ask the Experts™
on
I have never done the storage motion in production. I would like to do live storage motion,
Experts out there, I will appreciate your advice on this.
What will happen to vm if t it break during the storage motion?
Will the users be disconnected from the server?
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Commented:
Storage vMotion is either a 0 or 1, e.g. it works or it does not work, it completes or does not complete.

if the process fails, it just reverts back to the original location, as the process is transaction based.

no damage to the VM is done, if it fails, and the VM is not affected.

As for user disconnects, depends on the server, sometimes Exchange and /or Terminal Services, users can get disconnected. (depends on load on server, and datastore, disk types, e.g. slow datastores)

1. It's best not to Storage vMotion when a snapshot exists on the VM.

2. do not storage vMotion when a backup is occurring.

3. try to keep storage vMotions to outside of core hour, or when server activity is low.

4. ensure you have fast storage.
Hi,

Do you mean vmotion?

No. the purpose of vmotion is redundancy.. meaning if one server down your passive server will kick off and this is transparent to users
Haresh NikumbhSr. Tech lead
Top Expert 2013
Commented:
Once you start Storage Vmotion, the host reads all the data from datastore1 and write it to datastore2. so it does not affect primary datastore if copy process or job get failed.

so no need to worry if job get failed or did not get complete, inshort it does affect source datastore or vm.
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Top Expert 2015

Commented:
Storage vmotion will not use VAAI, so preferably move other machines especially IO sensitive out from the host you attempt storage vmotion on.
Haresh NikumbhSr. Tech lead
Top Expert 2013

Commented:
Storage vmotion will not use VAAI,

I do not agree..

If both array are from the same vendor, and if they support VAAI, then it will use VAAI, which make svmotion faster.
Top Expert 2015

Commented:
Storage vmotion on live machine WILL NOT USE VAAI even if it is supported. This limitation is very well documented in almost any VAAI paper from vmware and vendors.
On the other hand if VAAI is present it make clone/storage migration a snap
Haresh NikumbhSr. Tech lead
Top Expert 2013

Commented:
Limitations and conditions of VAAI
To move and copy VM data both within and across datastores, the VM kernel uses a software component called the VMFS
DataMover. The VMFS DataMover enables the cloning and initialization of VM data to provide high data throughput
without moving the data between the kernel and application levels. The VMFS DataMover is designed to work with VAAI
and automatically offloads the data movement to the storage hardware. However, in certain cases the VMFS DataMover
does not leverage hardware offloads and instead usessoftware data movement. These cases include:

• The source and destination VMFS volumes have different block sizes.

• The source file type is RDM (raw device mapping) ,and the destination file type is non-RDM (regular file).

•The source VMDK type isEZTand the destination VMDK type is thin.

•The source or destination VMDK is any sort of sparse or hosted format.

•The source VM has a snapshot.

• The logical address and transfer length in the requested operation are not aligned to the minimum alignment required
by the storage device (all datastores that are created with the vSphere Client are aligned automatically).

• The VMFS has multiple LUNs/extents and they are all on different arrays.

• Hardware cloning between different arrays (even if within the same VMFS volume) does not work


Source:
http://h20195.www2.hp.com/V2/GetPDF.aspx%2F4AA4-2158ENW.pdf

Also refer Frank denneman blog who is co-author DEEPDIVE Vmware vsphare book

http://frankdenneman.nl/2012/09/07/vsphere-5-1-vmotion-deepdive/


i will be thankful if you help me to find out such document where it mention live VM will not use VAAI
Top Expert 2015

Commented:
NAS VAAI full file copy...
Haresh NikumbhSr. Tech lead
Top Expert 2013

Commented:
Original question was already answered in first 3 post.

and if @gheist is right then wanted to see the document which i have missed.
Top Expert 2015

Commented:
Top Expert 2015

Commented:
Can you elaborate? i dont think this answer is the best one...
Haresh NikumbhSr. Tech lead
Top Expert 2013

Commented:
she/ he always select last replier answer as solution which is wrong.

previously I have escalated to moderator, to reassign point again for correct solution.

Author

Commented:
I must have selected multiple solutions.

Author

Commented:
i do not know which is best solution because I have not tried my self yet.
I do not have much knowledge on this filed to decide which is best solution.
I let the experts to decide which is the best solution.

Author

Commented:
I am happy with the solutions , but can not confirm that the correct solutions since I do not know myself. If i know the answer then I would not ask that question.
I believe that contributors are in best knowledge and believe it.

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