[ovirt-users] Re: ImageIO Performance
On Mon, Feb 6, 2023 at 10:00 AM Jean-Louis Dupond via Users
<users(a)ovirt.org> wrote:
Hi All,
We backup our VM's with a custom script based on the
https://github.com/oVirt/python-ovirt-engine-sdk4/blob/main/examples/back...
example.
This works fine, but we start to see scaling issues.
On VM's where there are a lot of dirty blocks,
We need to see the list of extents returned by the server.
The easiest way would be to enable debug logs - it will be even slower,
but we will see these logs showing all extents:
log.debug("Copying %s", ext)
log.debug("Zeroing %s", ext)
log.debug("Skipping %s", ext)
It will also show other info that can help to understand why it is slow.
the transfer goes really
slow (sometimes only 20MiB/sec).
Seems much slower than expected
At the same time we see that ovirt-imageio process sometimes uses
100%
CPU
This is possible, it shows that you do a lot of requests.
(its single threaded?).
It uses thread per connection model. When used with backup_vm.py or other
examples using the ovirt_imageio.client it usually use 4 connections
per transfer
so there will be 4 threads on the server size serving the data.
Please share debug log of a slow backup, and info about the backup image storage
for example, is this local file system or NFS?
Nir