problem accessing vm's after copying /home partition

[paddler]

Due to an unrelated-to-virtualbox problem, I had ICEauthority problems with my encrypted /home partition and I eventually copyied my /home to a new unencrypted /home partition. Unfortunately my virtualbox ubuntu guests (4 of them - 3 being clones) couldn't be accessed any longer. I eventually did get into the first one, got it closed with the "send shutdown signal" and its fine now. However the 3 clones are in the "saved" state and I cannot get them to complete a start up at all, so that I can then shut them down and try to fix them. The startups crash after I clear the following error msg:

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Failed to open a session for the virtual machine u2.
pdmblkcache#0: The VM is missing a block device. Please make sure the source and target VMs have compatible storage configurations [ver=1 pass=final] (VERR_SSM_LOAD_CONFIG_MISMATCH).

Result Code: 
NS_ERROR_FAILURE (0x80004005)
Component: 
Console
Interface: 
IConsole {515e8e8d-f932-4d8e-9f32-79a52aead882}

I tried vboxmanage showvminfo guestname and compared the first guest with each clone and I don't see any differences that I find suspect in the sata area, where I think the problem might be. I'm fairly new to vbox I should mention though. I was going to try using the storagectl --hostiocache command to fix the problem, but I'm afraid I may be barking up the wrong tree and I'll just permanently break things. Not sure where to go from here. Below is part of my showvminfo and the logfile, which (I think) probably cover the problem:

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Config file:     /home/thane/VirtualBox VMs/u2/u2.vbox
Snapshot folder: /home/thane/VirtualBox VMs/u2/Snapshots
Log folder:      /home/thane/VirtualBox VMs/u2/Logs
Hardware UUID:   4c56637c-bb73-4148-84c3-68d80456bff1
Memory size:     1024MB
Page Fusion:     off
VRAM size:       12MB
HPET:            off
Chipset:         piix3
Firmware:        BIOS
Number of CPUs:  1
Synthetic Cpu:   off
CPUID overrides: None
Boot menu mode:  message and menu
Boot Device (1): Floppy
Boot Device (2): DVD
Boot Device (3): HardDisk
Boot Device (4): Not Assigned
ACPI:            on
IOAPIC:          on
PAE:             off
Time offset:     0 ms
RTC:             UTC
Hardw. virt.ext: on
Hardw. virt.ext exclusive: on
Nested Paging:   on
Large Pages:     off
VT-x VPID:       on
State:           saved (since 2011-02-06T13:54:09.000000000)
Monitor count:   1
3D Acceleration: off
2D Video Acceleration: off
Teleporter Enabled: off
Teleporter Port: 0
Teleporter Address: 
Teleporter Password: 
Storage Controller Name (0):            IDE Controller
Storage Controller Type (0):            PIIX4
Storage Controller Instance Number (0): 0
Storage Controller Max Port Count (0):  2
Storage Controller Port Count (0):      2
Storage Controller Bootable (0):        on
Storage Controller Name (1):            SATA Controller
Storage Controller Type (1):            IntelAhci
Storage Controller Instance Number (1): 0
Storage Controller Max Port Count (1):  30
Storage Controller Port Count (1):      1
Storage Controller Bootable (1):        on
IDE Controller (1, 0): Empty
SATA Controller (0, 0): /home/thane/VirtualBox VMs/u2/u2.vdi (UUID: ed72e675-24ed-40a7-b5b7-0baa2d9f7546)

logfile

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00:00:00.626 File system of '/home/thane/VirtualBox VMs/u2/Snapshots' (snapshots) is ext4
00:00:00.626 File system of '/home/thane/VirtualBox VMs/u2/u2.vdi' is ext4
00:00:00.627 Console: VM runtime error: fatal=false, errorID=Ext4PartitionDetected message="The host I/O cache for at least one controller is disabled and the medium '/home/thane/VirtualBox VMs/u2/u2.vdi' for this VM is located on an ext4 partition. There is a known Linux kernel bug which can lead to the corruption of the virtual disk image under these conditions.
00:00:00.627 Either enable the host I/O cache permanently in the VM settings or put the disk image and the snapshot folder onto a different file system.
00:00:00.627 The host I/O cache will now be enabled for this medium"
00:00:00.649 VBoxSharedClipboard mode: Bidirectional
00:00:00.654 ************************* CFGM dump *************************
00:00:00.654 [/] (level 0)
00:00:00.654   CSAMEnabled     <integer> = 0x0000000000000001 (1)
00:00:00.654   CpuExecutionCap <integer> = 0x0000000000000064 (100)
00:00:00.654   EnablePAE       <integer> = 0x0000000000000000 (0)
00:00:00.654   HwVirtExtForced <integer> = 0x0000000000000000 (0)
00:00:00.654   MemBalloonSize  <integer> = 0x0000000000000000 (0)
00:00:00.654   Name            <string>  = "u2" (cb=3)
00:00:00.654   NumCPUs         <integer> = 0x0000000000000001 (1)
00:00:00.654   PATMEnabled     <integer> = 0x0000000000000001 (1)
00:00:00.654   PageFusion      <integer> = 0x0000000000000000 (0)
00:00:00.654   RamHoleSize     <integer> = 0x0000000020000000 (536870912)
00:00:00.654   RamSize         <integer> = 0x0000000040000000 (1073741824)
00:00:00.654   RawR0Enabled    <integer> = 0x0000000000000001 (1)
00:00:00.654   RawR3Enabled    <integer> = 0x0000000000000001 (1)
00:00:00.654   SyntheticCpu    <integer> = 0x0000000000000000 (0)
00:00:00.654   TimerMillies    <integer> = 0x000000000000000a (10)
00:00:00.654   UUID            <bytes>   = "7c 63 56 4c 73 bb 48 41 84 c3 68 d8 04 56 bf f1" (cb=16)
00:00:00.654 
00:00:00.654 [/CPUM/] (level 1)
00:00:00.654 
00:00:00.654 [/Devices/] (level 1)
00:00:00.654 
00:00:00.654 [/Devices/8237A/] (level 2)
00:00:00.654 
00:00:00.654 [/Devices/8237A/0/] (level 3)
00:00:00.654   Trusted <integer> = 0x0000000000000001 (1)
00:00:00.654 
00:00:00.654 [/Devices/AudioSniffer/] (level 2)
00:00:00.654 
00:00:00.654 [/Devices/AudioSniffer/0/] (level 3)
00:00:00.654 
00:00:00.654 [/Devices/AudioSniffer/0/Config/] (level 4)
00:00:00.654 
00:00:00.654 [/Devices/AudioSniffer/0/LUN#0/] (level 4)
00:00:00.654   Driver <string>  = "MainAudioSniffer" (cb=17)
00:00:00.654 
00:00:00.654 [/Devices/AudioSniffer/0/LUN#0/Config/] (level 5)
00:00:00.654   Object <integer> = 0x00000000021b71e0 (35353056)
00:00:00.654 
00:00:00.654 [/Devices/VMMDev/] (level 2)
00:00:00.654 
00:00:00.654 [/Devices/VMMDev/0/] (level 3)
00:00:00.654   PCIBusNo      <integer> = 0x0000000000000000 (0)
00:00:00.654   PCIDeviceNo   <integer> = 0x0000000000000004 (4)
00:00:00.654   PCIFunctionNo <integer> = 0x0000000000000000 (0)
00:00:00.654   Trusted       <integer> = 0x0000000000000001 (1)
00:00:00.654 
00:00:00.654 [/Devices/VMMDev/0/Config/] (level 4)
00:00:00.654   GuestCoreDumpDir <string>  = "/home/thane/VirtualBox VMs/u2/Snapshots" (cb=40)
00:00:00.654   RamSize          <integer> = 0x0000000040000000 (1073741824)
00:00:00.654 
00:00:00.654 [/Devices/VMMDev/0/LUN#0/] (level 4)
00:00:00.654   Driver <string>  = "HGCM" (cb=5)
00:00:00.654 
00:00:00.654 [/Devices/VMMDev/0/LUN#0/Config/] (level 5)
00:00:00.654   Object <integer> = 0x00007fd72c0497d0 (140562133194704)
00:00:00.654 
00:00:00.654 [/Devices/VMMDev/0/LUN#999/] (level 4)
00:00:00.654   Driver <string>  = "MainStatus" (cb=11)
00:00:00.654 
00:00:00.654 [/Devices/VMMDev/0/LUN#999/Config/] (level 5)
00:00:00.654   First   <integer> = 0x0000000000000000 (0)
00:00:00.654   Last    <integer> = 0x0000000000000000 (0)
00:00:00.654   papLeds <integer> = 0x00000000021b3518 (35337496)
00:00:00.654 
00:00:00.654 [/Devices/acpi/] (level 2)
00:00:00.654 
00:00:00.654 [/Devices/acpi/0/] (level 3)
00:00:00.654   PCIBusNo      <integer> = 0x0000000000000000 (0)
00:00:00.654   PCIDeviceNo   <integer> = 0x0000000000000007 (7)
00:00:00.654   PCIFunctionNo <integer> = 0x0000000000000000 (0)
00:00:00.654   Trusted       <integer> = 0x0000000000000001 (1)
00:00:00.654 
00:00:00.654 [/Devices/acpi/0/Config/] (level 4)
00:00:00.654   CpuHotPlug        <integer> = 0x0000000000000000 (0)
00:00:00.654   FdcEnabled        <integer> = 0x0000000000000000 (0)
00:00:00.654   HostBusPciAddress <integer> = 0x0000000000000000 (0)
00:00:00.654   HpetEnabled       <integer> = 0x0000000000000000 (0)
00:00:00.654   IOAPIC            <integer> = 0x0000000000000001 (1)
00:00:00.654   IocPciAddress     <integer> = 0x0000000000010000 (65536)
00:00:00.654   NumCPUs           <integer> = 0x0000000000000001 (1)
00:00:00.654   RamHoleSize       <integer> = 0x0000000020000000 (536870912)
00:00:00.654   RamSize           <integer> = 0x0000000040000000 (1073741824)
00:00:00.654   ShowCpu           <integer> = 0x0000000000000001 (1)
00:00:00.654   ShowRtc           <integer> = 0x0000000000000000 (0)
00:00:00.654   SmcEnabled        <integer> = 0x0000000000000000 (0)
00:00:00.654 
00:00:00.654 [/Devices/acpi/0/LUN#0/] (level 4)
00:00:00.654   Driver <string>  = "ACPIHost" (cb=9)
00:00:00.654 
00:00:00.654 [/Devices/acpi/0/LUN#0/Config/] (level 5)
00:00:00.654 
00:00:00.654 [/Devices/ahci/] (level 2)
00:00:00.654 
00:00:00.654 [/Devices/ahci/0/] (level 3)
00:00:00.654   PCIBusNo      <integer> = 0x0000000000000000 (0)
00:00:00.654   PCIDeviceNo   <integer> = 0x000000000000000d (13)
00:00:00.654   PCIFunctionNo <integer> = 0x0000000000000000 (0)
00:00:00.654   Trusted       <integer> = 0x0000000000000001 (1)
00:00:00.654 
00:00:00.654 [/Devices/ahci/0/Config/] (level 4)
00:00:00.654   Bootable        <integer> = 0x0000000000000001 (1)
00:00:00.654   PortCount       <integer> = 0x0000000000000001 (1)
00:00:00.654   PrimaryMaster   <integer> = 0x0000000000000000 (0)
00:00:00.654   PrimarySlave    <integer> = 0x0000000000000001 (1)
00:00:00.654   SecondaryMaster <integer> = 0x0000000000000002 (2)
00:00:00.654   SecondarySlave  <integer> = 0x0000000000000003 (3)
00:00:00.654 
00:00:00.654 [/Devices/ahci/0/LUN#0/] (level 4)
00:00:00.654   Driver <string>  = "Block" (cb=6)
00:00:00.654 
00:00:00.654 [/Devices/ahci/0/LUN#0/AttachedDriver/] (level 5)
00:00:00.654   Driver <string>  = "VD" (cb=3)
00:00:00.654 
00:00:00.654 [/Devices/ahci/0/LUN#0/AttachedDriver/Config/] (level 6)
00:00:00.654   Format <string>  = "VDI" (cb=4)
00:00:00.654   Path   <string>  = "/home/thane/VirtualBox VMs/u2/u2.vdi" (cb=37)
00:00:00.654   Type   <string>  = "HardDisk" (cb=9)
00:00:00.655 
00:00:00.655 [/Devices/ahci/0/LUN#0/Config/] (level 5)
00:00:00.655   Mountable <integer> = 0x0000000000000000 (0)
00:00:00.655   Type      <string>  = "HardDisk" (cb=9)
00:00:00.655 
00:00:00.655 [/Devices/ahci/0/LUN#999/] (level 4)
00:00:00.655   Driver <string>  = "MainStatus" (cb=11)
00:00:00.655 
00:00:00.655 [/Devices/ahci/0/LUN#999/Config/] (level 5)
00:00:00.655   First   <integer> = 0x0000000000000000 (0)
00:00:00.655   Last    <integer> = 0x0000000000000000 (0)
00:00:00.655   papLeds <integer> = 0x00000000021b3328 (35337000)
00:00:00.655 
00:00:00.655 [/Devices/apic/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/apic/0/] (level 3)
00:00:00.655   Trusted <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/apic/0/Config/] (level 4)
00:00:00.655   IOAPIC  <integer> = 0x0000000000000001 (1)
00:00:00.655   NumCPUs <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/e1000/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/e1000/0/] (level 3)
00:00:00.655   PCIBusNo      <integer> = 0x0000000000000000 (0)
00:00:00.655   PCIDeviceNo   <integer> = 0x0000000000000003 (3)
00:00:00.655   PCIFunctionNo <integer> = 0x0000000000000000 (0)
00:00:00.655   Trusted       <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/e1000/0/Config/] (level 4)
00:00:00.655   AdapterType    <integer> = 0x0000000000000000 (0)
00:00:00.655   CableConnected <integer> = 0x0000000000000001 (1)
00:00:00.655   LineSpeed      <integer> = 0x0000000000000000 (0)
00:00:00.655   MAC            <bytes>   = "08 00 27 58 93 ec" (cb=6)
00:00:00.655 
00:00:00.655 [/Devices/e1000/0/LUN#0/] (level 4)
00:00:00.655   Driver <string>  = "NAT" (cb=4)
00:00:00.655 
00:00:00.655 [/Devices/e1000/0/LUN#0/Config/] (level 5)
00:00:00.655   AliasMode       <integer> = 0x0000000000000000 (0)
00:00:00.655   BootFile        <string>  = "u2.pxe" (cb=7)
00:00:00.655   DNSProxy        <integer> = 0x0000000000000000 (0)
00:00:00.655   Network         <string>  = "10.0.2.0/24" (cb=12)
00:00:00.655   PassDomain      <integer> = 0x0000000000000001 (1)
00:00:00.655   TFTPPrefix      <string>  = "/home/thane/.VirtualBox/TFTP" (cb=29)
00:00:00.655   UseHostResolver <integer> = 0x0000000000000000 (0)
00:00:00.655 
00:00:00.655 [/Devices/e1000/0/LUN#999/] (level 4)
00:00:00.655   Driver <string>  = "MainStatus" (cb=11)
00:00:00.655 
00:00:00.655 [/Devices/e1000/0/LUN#999/Config/] (level 5)
00:00:00.655   papLeds <integer> = 0x00000000021b34d8 (35337432)
00:00:00.655 
00:00:00.655 [/Devices/i8254/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/i8254/0/] (level 3)
00:00:00.655 
00:00:00.655 [/Devices/i8254/0/Config/] (level 4)
00:00:00.655 
00:00:00.655 [/Devices/i8259/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/i8259/0/] (level 3)
00:00:00.655   Trusted <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/i8259/0/Config/] (level 4)
00:00:00.655 
00:00:00.655 [/Devices/ichac97/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/ichac97/0/] (level 3)
00:00:00.655   PCIBusNo      <integer> = 0x0000000000000000 (0)
00:00:00.655   PCIDeviceNo   <integer> = 0x0000000000000005 (5)
00:00:00.655   PCIFunctionNo <integer> = 0x0000000000000000 (0)
00:00:00.655   Trusted       <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/ichac97/0/Config/] (level 4)
00:00:00.655 
00:00:00.655 [/Devices/ichac97/0/LUN#0/] (level 4)
00:00:00.655   Driver <string>  = "AUDIO" (cb=6)
00:00:00.655 
00:00:00.655 [/Devices/ichac97/0/LUN#0/Config/] (level 5)
00:00:00.655   AudioDriver <string>  = "pulse" (cb=6)
00:00:00.655   StreamName  <string>  = "u2" (cb=3)
00:00:00.655 
00:00:00.655 [/Devices/ioapic/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/ioapic/0/] (level 3)
00:00:00.655   Trusted <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/ioapic/0/Config/] (level 4)
00:00:00.655 
00:00:00.655 [/Devices/mc146818/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/mc146818/0/] (level 3)
00:00:00.655 
00:00:00.655 [/Devices/mc146818/0/Config/] (level 4)
00:00:00.655   UseUTC <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/parallel/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/pcarch/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/pcarch/0/] (level 3)
00:00:00.655   Trusted <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/pcarch/0/Config/] (level 4)
00:00:00.655 
00:00:00.655 [/Devices/pcbios/] (level 2)
00:00:00.655 
00:00:00.655 [/Devices/pcbios/0/] (level 3)
00:00:00.655   Trusted <integer> = 0x0000000000000001 (1)
00:00:00.655 
00:00:00.655 [/Devices/pcbios/0/Config/] (level 4)
00:00:00.655   BootDevice0            <string>  = "FLOPPY" (cb=7)
00:00:00.655   BootDevice1            <string>  = "DVD" (cb=4)
00:00:00.655   BootDevice2            <string>  = "IDE" (cb=4)
00:00:00.655   BootDevice3            <string>  = "NONE" (cb=5)
00:00:00.655   FloppyDevice           <string>  = "i82078" (cb=7)
00:00:00.655   HardDiskDevice         <string>  = "piix3ide" (cb=9)
00:00:00.655   IOAPIC                 <integer> = 0x0000000000000001 (1)
00:00:00.655   LanBootRom             <string>  = "/usr/lib/virtualbox/ExtensionPacks/Oracle_VM_VirtualBox_Extension_Pack/PXE-Intel.rom" (cb=85)
00:00:00.655   McfgBase               <integer> = 0x0000000000000000 (0)
00:00:00.655   McfgLength             <integer> = 0x0000000000000000 (0)
00:00:00.655   NumCPUs                <integer> = 0x0000000000000001 (1)
00:00:00.655   PXEDebug               <integer> = 0x0000000000000000 (0)
00:00:00.655   RamHoleSize            <integer> = 0x0000000020000000 (536870912)
00:00:00.655   RamSize                <integer> = 0x0000000040000000 (1073741824)
00:00:00.655   SataHardDiskDevice     <string>  = "ahci" (cb=5)
00:00:00.655   SataPrimaryMasterLUN   <integer> = 0x0000000000000000 (0)
00:00:00.655   SataPrimarySlaveLUN    <integer> = 0x0000000000000001 (1)
00:00:00.655   SataSecondaryMasterLUN <integer> = 0x0000000000000002 (2)
00:00:00.655   SataSecondarySlaveLUN  <integer> = 0x0000000000000003 (3)
00:00:00.655   UUID                   <bytes>   = "7c 63 56 4c 73 bb 48 41 84 c3 68 d8 04 56 bf f1" (cb=16)
00:00:00.655 
00:00:00.655 [/Devices/pcbios/0/Config/NetBoot/] (level 5)

Many thanks.

Oops. Editing here. Should have mentioned, that I'm using vbox 4.0.2 with additions 4.0.2 and extensions 4.0.0 on an ubuntu host. And also there's nothing wrong with my winxp guest. Only ubuntu guests seemed to be affected.

[paddler]

Saw another related post to this and one member just gave a solution, which worked perfectly. Saved me lots of time recloning my ubuntu vm's. Thanks to bho. http://forums.virtualbox.org/viewtopic. ... 62#p174262

[OldeFoxx]

Let me lay this matter out in simplist terms:

First, you only use one host. You might call this the Parent OS, and that is the one you boot up into. If you have a multi-boot configuration, you still have just one OS that is currently running the whole PC. You may have multiple cores in your PC, but they interact with each other. Someday someone may branch out where each core has its own host and they act independently, but then you might need a keyboard, mouse, monitor, and separate drives for each. That might do for a classroom or a group effort somewhere, but I kind of doubt mere humans can rise to the task of using all that at once by themselves.

Second, you introduce an application called a Virtual Machine that gets the host OS to perform a number of tasks for it. But the VM does not do this on its own. It has what we call clients that make specific requests for services. And the clients are actually other OSes that the user adds, essentially having you do a new install for each one in turn and add any applications to go with them. But what you learn is, that the virtual disk used to base this OS is actually just a file managed by the VM, and files can be duplicated simply by copying them. In the original implementation of VirtualBox as a VM, one clone was as good as another, but somebody realized that is not always a good thing, so they added the UUID, and once the UUID is registered with one of the clients, no other client is allowed to share it. So now making a clone is no longer enough, you somehow have to end up with different UUIDs to keep them separate.

Some discussion on these forums shows that some people think that the host drive's
UUID gets tangled up in this mess, but the mess is simply the intertangle with the client virtual drives when you copy them or clone them. The easiest way to deal with this is use a command feature of VirtualBox, and this is a documented command by the way, with no great mystery to it. But there are two versions of the command, and you have to use the right one for your version of VirtualBox.

The initial version went like this:
VBoxManage internalcommands setvdiuuid yourcopy.vdi

But that is now replaced by:
VBoxManage internalcommands sethduuid yourcopy.vdi

The difference and reason may not be immediately apparent, but the second parameter was changed from having "vdi" included to use "hd". The vdi was fine as long as VirtualBox only supported the vdi format, but it is expanding to take in all manner of virtual image formats, so instead of specifying just one, they changed it to just reference the fact that it is a virtual hard disk image that is involved.

[OldeFoxx]

Noting the original complaint of copying the /home partition, I take it that you have multiple disks and/or partitions and have one set up as /home. Since you also mention VM's as plural, I take it that you are setting up multiple clients, and if I am not mistaken, having them all share the same /home partition.

Let me tell you a little true story. When I was about 12, my dad got interested in learning to fly. So he took lessons. Then he wanted a plane, but they are expensive.
There were four other guys there where he worked that were also into flying, so they decided to go in together and split the costs of buying a two seater Tailorcraft. They got one cheap, but only to learn that the body and wing fabric was rotten, so they flew the plane to a farm near our house, and my dad and mom worked long hours recovering the whole plane and getting it up to requirements. My mom just did her part with a featherweight sewing machine from Singer. My dad did the calculations and cutting, then stretching the material on the framework and lacquering it over. Finally it was done, recertified, and the fun was to start. Since there were five of them, they decided to divide the weekends in fifths, meaning Friday pm, Saturday am, Saturday pm, Sunday am, and Sunday pm. They came up with an alternating schedule of rotation, and the agreement was have it back on time and top off the fuel before leaving. Only it never worked out that way. My dad would grab me or one of my sibblings and head to the airport 35 miles away, and either the plane would not be there, or he would have to spend an hour servicing it and refueling it before he could take to the air. See the problem here. One plane and five people to share. He finally bought out the others and then it was there when he wanted it.

Every personal account you set up under home may know not just each user, but the configuration that the system should be under when that user is logged in. You set up just one /home partition, you are inviting tremendous overlap. now I suppose that if you add new installs and add new user names with each install, you might fare alright. I won't swear to it though, because I wanted to use the same userid with each one, but not leave it to chance that the new install would latch onto an existing /home partition. I worked it out, found some commands that helped with the details, and now I have three Ubuntu installs on one PC, but each is independent of the other two.
share the same account or configuration. To do that, each install had to have its own partition