[ovirt-users] Re: [External] : oVirt slow backups from ISCSI storage domain to nfs target

Hi Don, When transferring small files to an NFS share, many times, they can fit the in-memory cache, leading to high transfer rates. For bigger files, the remote NFS storage will need to commit data to the disk once the cache is filled. In general, it is common to see the initial data transfer at high numbers, slowing down as the transfer continues. This behavior is not only with NFS shares; you may face the same behavior using scp. Anyway, it is recommended that a transfer test be run using other methods to confirm this is the cause. Marcos From: Don Dupuis <dondster(a)gmail.com&gt; Sent: Friday, November 8, 2024 5:06 PM To: users <users(a)ovirt.org&gt; Subject: [External] : [ovirt-users] oVirt slow backups from ISCSI storage domain to nfs target Hi I am using oVirt 4.4.10.7 with vms on iscsi Lenovo DE-6600F(nvme interfaced ssds). Backing up thin vms performance is fine, but with preallocated disks, backups to nfs storage with 200Gb interface is only transferring qcow2 image to nfs at 140MiB per sec. Why is qemu-nbd so slow with preallocated images? Does anyone have any issues related to this? Any help would be appreciated. I have made iscsid.conf changes, linux kernel boot changes, and still the same performance. Thanks Don