Ticket #10726 (new defect)

Opened 22 months ago

Last modified 20 months ago

Disk writes only at shutdown

Reported by: q Owned by:
Priority: major Component: virtual disk
Version: VirtualBox 4.1.18 Keywords: Disk writes only at shutdown cache flush
Cc: Guest type: Linux
Host type: Windows


I am running VirtualBox 4.1.18 on W7 x64 and running a Linux guest. The problem is that disk writes are only written on the VDI file when the VM exits. The problem here is that if the system hangs or there is a problem the changes to the VM wont be written to the VDI. It is a problem to me as the VM runs for days without shutting down.

I started running a VMDK VM created with VMWARE Server. The guest was installed on the SCSI interface. At first I thought this was the problem so I created and installed a new VM with Virtual box and a new vdi on the SATA interface. Reinstalled Linux. Tried running Headless and from the GUI.

Have tried with "Use Host IO" option on and off,

VBoxManage setextradata "elastix" "VBoxInternal/Devices/ahci/0/LUN#0/Config/IgnoreFlush" 0

VBoxManage setextradata "elastix" "VBoxInternal/Devices/ahci/0/LUN#0/Config/FlushInterval" 1

Turned Host Windows Write Cache off

The VBoxManage settings seem to be in the .vbox file but when the VM shutsdown those settings are moved to the -prev file and removed from the .vbox file.

Nothing seems to help.

There has to be a way to make disk writes be written on the vdi file immediately.

Change History

comment:1 Changed 20 months ago by frank

The statement that disk changes wouldn't be written to the physical disk until the VM shuts down is wrong. It is true that VirtualBox caches disk writes but this is the same behavior as other applications show. Kill your editor and you will observe that parts of your written documents are gone. And the host will cache data itself so if your host crashes then some of your unsaved data will be lost as well.

It would help if you could show where your problem is. Even if you force VirtualBox to not ignore the flush command from the guest controller then still can't be 100% certain that the data arrived the physical disk.

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