[ovirt-devel] Re: [EXTERNAL] Re: List of Queries related to RHV

On Wed, Oct 17, 2018 at 5:03 PM Mahesh Falmari <Mahesh.Falmari(a)veritas.com&gt; wrote: Right, this is only for internal use. ... Arik, can you answer this? Regarding backup, I think you need to store the vm configuration at the time of the backup regardless of having a version or not. The amount of data is very small. Using the UI you can use qcow2 format only for thin disks on block storage. Using the SDK you can also create qcow2 image on thin file based storage. You can see examples here: https://github.com/oVirt/ovirt-engine-sdk/blob/78c3d5bd14eeb93ef72ec31d77... In 4.3 we plan to support qcow2 image format for both thin and preallocated disks to allow change block tracking for incremental backup. See html: https://github.com/oVirt/ovirt-site/blob/bc51f4a7867d9c7e3797da6da1d19e11... I don't know about any stats from users, but the general idea is: - one engine - 1 or more DCs - 1 or more storage domains in a DC - 1 or more clusters per DCs - 1 or more hosts per cluster The theoretical limit is 2000 hosts per DC (limited by sanlock), but the practical limit is much lower. I don't think we have setups with more than 200 hosts. Martin, do you have more info on this? It sounds like a reasonable speed up. Can RHVM server requests in parallel, Yes > if so are there any settings that need to be tweaked? We don't have any settings related to concurrency. > [Mahesh] Seeking response to this query. The throughout you will get depends on many things: - are you communicating with the proxy (using proxy_url) or the daemon (transfer_url)? Accessing the daemon directly will be faster. - are you running on the same host as the daemon performing the transfer? - if you run on the same host, are you using unix socket? (15% improvement expected) - are you using the same connection per thread for entire transfer (huge improvement when doing small requests) - which version are you testing? we support keep alive connections only since 1.4.x. - are you using big enough requests? you will get best performance if you use one big request per thread - network bandwidth - storage speed For best throughput when downloading single disk, you should use multiple threads, each downloading one part of an image, but I'm not sure it worth the time to optimize this since backup are expected the run in the same time anyway, and you will quickly reach the storage limit while downloading disks for multiple vms on multiple hosts in the same time. I suggest testing the expected use case, not single download. snapshots are always consistent if you have qemu guest agent installed, and the guest is using the guest agent scripts properly. Without the guest agent, or if it is not configured properly, file system will have to recover after restore, in the same way it recovers after power failure. To be able to resume a vm to the same state when the snapshot was done you need to include memory in the snapshot, but this make the snapshot much slower, depending on the amount of guest memory, and require huge amount of space, so I don't think it makes sense for backup. Regarding REST API, Arik can add more info about this. Nir