Friday, October 23, 2009

Storage VMotion myth and deep dive

I had been involved so heavily in storage Vmotion that I decided to write about it. Nice source is here

First of all storage vmotion is

  1. Takes an ESX snapshot
  2. Then file copies the closed VDMK (which is the large majority of the VM) to the target datastore
  3. Then "reparents" the open (and small) VDMK to the target (synchronizing)
  4. Then "deletes" the snapshot (in effect merging the large VDMK with the small reparented VMDK)

Myth and deepdive:

  1. In a cluster if you have 5 host and have 10 luns. If you want to svmotion to 11th lun, the 11th lun should be visible to all the host in the cluster. It does not work on individual host
  2. You can do 1 svmotion per ESX host and maximum of 32 per cluster (Pheew)

  1. You can have 4 svmotion per lun . Which means you have many source lun but at a time only 4 svmotion will done at any target lun

  1. Storage vmotion can happen be only between on datacenter and cannot happen between two different datacenter (phewee).
  2. Storage VMotion cannot be used on a virtual machine with NPIV enabled

Batch Storage Vmotion

I had to do batch svmotoion and I decided to follow this guy nice article

Place postie.exe (Freeware), AutoSVmotion.vbs (Contents at then ) in the Remote CLI (Download and install it from VMWare site) bin directory (default location is "C:\Program Files\VMWare\VMWare VI Remote CLI\Bin"). Also create a batch file in this directory, this will be used to call AutoSVMotion.vbs. In the batch file put all the VM's that you require migrating in the below format:

cscript.exe AutoSVmotion.vbs %VC% %Username% %Password% %Datacentre% %SourceDatastore% %VMXFilePath% %DestDatastore% %SMTPServ% %ToEmailAddress% %FromEmailAddress%

Example of the batch file:

cscript.exe AutoSVmotion.vbs VC01 Admin P@ssw0rd London OLDLUN1 VM1/VM1.vmx NewLUN1 SMTP01
cscript.exe AutoSVmotion.vbs VC01 Admin P@ssw0rd London OLDLUN1 VM2/VM2.vmx NewLUN1 SMTP01

Example of the email output:

Date: 13 September 2009 08:45:43 GMT+01:00
Subject: SVMotion Progress Report

Successfully migrated VM1/VM1.vmx

Contents of AutoSVmotion.vbs

Dim WshShell, oArgs, sVCServer, sUsername, sPassword, sDatacenter, sSourceStore, sVMXLocation,_

sDestStore, sSMTPServer, sEmailAddress, sSVMotioncmd, iRetVal, sEMailText, sEmailCmd

On Error Resume Next

Set WshShell = WScript.CreateObject("WScript.Shell")

Set oArgs = WScript.Arguments

sVCServer = oArgs(0)

sUsername = oArgs(1)

sPassword = oArgs(2)

sDatacenter = oArgs(3)

sSourceStore = oArgs(4)

sVMXLocation = oArgs(5)

sDestStore = oArgs(6)

sSMTPServer = oArgs(7)

sToEmailAddress = oArgs(8)

sFromEmailAddress = oArgs(9)

sSVMotioncmd = "cmd.exe /c --url=https://" & sVCServer & "/sdk --username=" & sUsername & _

" --password=" & sPassword & " --datacenter=" & sDatacenter & " --vm=" & Chr(34) & "[" & sSourceStore & "] " & sVMXLocation &_

":" & sDestStore & Chr(34)

WScript.Echo sSVMotioncmd

iRetVal = WshShell.Run(sSVMotioncmd, 1, True)

If iRetVal = 0 Then

sEMailText = "Successfully migrated " & sVMXLocation

sEmailCmd = "cmd.exe /c postie.exe -host:" & sSMTPServer & " -to:" & sToEmailAddress & " -from:" & sFromEmailAddress & " -s:" & Chr(34) & "SVMotion Progress Report" & Chr(34) & " -msg:" & Chr(34) & sEMailText & Chr(34)


sEMailText = "SVmotion failed for " & sVMXLocation & " with error number " & iRetVal

sEmailCmd = "cmd.exe /c postie.exe -host:" & sSMTPServer & " -to:" & sToEmailAddress & " -from:" & sFromEmailAddress & " -s:" & Chr(34) & "SVMotion Progress Report" & Chr(34) & " -msg:" & Chr(34) & sEMailText & Chr(34)

End If

WshShell.Run sEmailCmd, 1, True


Anonymous said...

Roy thanks for the article. I need to vmotion a file server that was partition incorrectly to a new SAN (after it we will correct the partitions). The problem is that the vmfs LUN is full. I can turn off the server while I a moving storage, will that require to create a snap too?

Vikash Kumar Roy said...

I am assuming that you are using new version of ESX ? Even with older version 4.0 SVM does not require snapshot . You don't need to shut down the VM's if you have licensed it. It can be hot migration.