Re: [ovirt-users] VMs seems to be slow, while snapshot delete is happening
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 ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
Re: [ovirt-users] VMs seems to be slow, while snapshot delete is happening
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 Advance thanks, Satheesaran S ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
[ovirt-users] VMs seems to be slow, while snapshot delete is happening
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 ? Advance thanks, Satheesaran S ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
