On 05/14/2016 02:38 AM, Greg Padgett wrote:
On 05/12/2016 03:46 AM, SATHEESARAN wrote:
Hi All,
I have created a VM with 60GB of disk space. I have started I/O inside the VM, after sometime when the disk was 4GB full, I took a snapshot of the disk from UI.
I/O kept continuing and the new image file ( overlay file ) was 15GB in size.
Now I deleted the snapshot. I think this would initiate block-merges. During this time, my I/O was were slower, till the snapshot delete is completed.
Its not very slow, but slow. Is this a known behavior ?
Hi Satheesaran,
It sounds like this was a live merge, ie snapshot removal while the VM was running. This is currently implemented as a block commit, where data from the snapshot (your 15GB overlay, in this case) is merged down.
For snapshot deletion to complete, this means that your concurrent I/O and the data already in the overlay have to be written into the next-lower image. So in short, yes, depending on the storage system backing your VM, I/O may slow down a bit until completion.
HTH, Greg Greg,
Thanks for that information. I too expected it, but really wanted to confirm the behavior. -- Satheesaran S