On Mon, Feb 6, 2023 at 10:00 AM Jean-Louis Dupond via Users
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/backup_vm.py
> 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
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