@DustinB Indeed I will, but are the prices really that close? I was looking a few weeks ago with some replacements and spinning was still enough cheaper that it made a difference. I was looking for around 4tb enterprise class drives.

@ItzJay in your journalctl -i xo-server log you should have something like nbdkit logs of ${diskPath} are in ${tmpDir} where tmpDir is something like /tmp/xo-serverXXXX/stderr can you post the file ? alternatively, you can open a support ticket

thanks Andryi We us round robin when using NBD , but to be fair, it does not change the performance a lot in most of the case. The concurrency settings ( multiple connection to the same file ) is helping when there is a high latency between XO and the host. SO , @fcgo if you have thousand of VMs , you should enable NBD it will consume less resource on the DOM0 and XO , and it will be spread on all the possible hosts.

@deligatedgeek are you modifying the chunk for delta or full backup ? because a lot of part in the incremental code assume that blocks are aligned to 2MB For full backup ( one big xva file per VM) the code should handle file with a size bigger than 4GB , by dynamically increasing the chunk size. We do not increase the chunk size by default because it also increase a lot the memory consumption. The minimum size of a chunk is given by MIN_PART_SIZE ( 5MB as per AWS doc ) and the maximum size is MAX_PART_SIZE ( 5GB) . The maximum file is 50TB , the biggest full backup I saw in the wild was a few hundred GB

@Forza Too funny. I came across this post and clicked on the URL you referenced......and that earlier question was from me! Well, nothing has changed. I'm doing mirror'ed backups and I'm still blind as a bat.