vMotion disk to another lun

[dranik416]

HI There,

We have a server that outgrew its LUN.

This VM has multiple drives and as a temp solution we are thinking to vMotion one of the drives to a neighboring LUN on the same SAN.

• What are the drawbacks of doing so except that in future if we would want to migrate this VM to another storage, we'll have to temporarily remove this particular disk before doing so?

And one more question: this particular machine has 720 GBs of RAM. And of course there is a huge .vswp. Please let me know if there are any feasible options to:

a) put it someplace else if keeping it on local datastore is not an option?,

b) what are the consequences to disable it altogether?

c) any other advice on vswp file?

Please share your knowledge and experience.

Thank you.

[RAJ_RAJ]

Hi ,

You can keep the vswp on another data tore

if you want to move only one disk it can be performed from advance option on the storage migration window , so there won't we be much impact .

In future if you are moving the vm to new storage without the disk , data won't available and any application settings resides on that it won't work ,

[RParker]

And one more question: this particular machine has 720 GBs of RAM. And of course there is a huge .vswp

If you set the VM resource to reserved for ALL of the RAM, you will not have vswp file, but the vswp is not migrated at any rate, so it's not a problem.

Moving to another LUN has no drawback except a little performance if LUN is on same SAN volume you might take a performance hit otherwise no drawback.

You can move .vswp to local host but it's not recommended you only NEED the swap if you exhaust ALL of guest RAM, 720GB is a LOT to consume have you checked the guest OS memory usage for that RAM?  I seriously doubt you are truly using all of it..

[dranik416]

Hi,

Could you please clarify what do you mean by 'In future if you are moving the vm to new storage without the disk , data won't available and any application settings resides on that it won't work "

My understanding is that it will vmotion all drives to one LUN, which means that what I will have to do is to remove the drive prior to migrating to another SAN and then re-attach.And it should work.

[dranik416]

Hi,

LUNs are on the same SAN. Why do you think there will be performance hit. I think it is the opposite, number of iOPS will increase.

In terms of RAM, I am not sure removing vswp file (disable it) is useful. At least that's what VMware engineer said.

so, I am planning to keep it. This VM has a lot of RAM, yes, as we want SQL to dump database into flash.

Thank you

[RAJ_RAJ]

Hi ,

Example , if one vm having  2 drives one is OS and another data and some application data like wsus .

You can disconnected driver and do vmotion only c drive and power on vm  .

In most of the cases we do storage vmotion of full vm , but some case due to storage space issue  only C ad required drives will move rest wil lkeep offline  untill there is enough capacity on new storage and old storage disconnected from host not powered off.

[nparas5]

Can't the datastore be extended, look for the option to increase the datastore.

Seeing the RAM Size better to Create a New Datastore for the SWAP File.

[senthilkumarms8]

Hi,

StoragevMotion the disk to another datastore will not cause any impact. but make sure you same class of LUN/datastore (SSD or SAS) before migrating the particular disk. if it is not a same class of LUNs then you might face some IO performance issues

On vSwp

a) put it someplace else if keeping it on local datastore is not an option?

If we place the vswp file local datastore then it will impact the vmotion. during the VMotion the entire vswp file will be copied to target host over the vMotion network.

b) what are the consequences to disable it altogether?

100% memory reservation should not create the vswp file. however, you need to consider the host memory size and other VMs provisioned memory size failover scenario.

other device on vswp file?

keep the vswp file in different shared datastore or do the 100% memory reservation.