Hello, I am translating the Veeam Help Center User Guide for VMware vSphere into my local language via google translation. There is a paragraph I don't understand.
Veeam Backup & Replication uses the Direct SAN access transport mode to read and write VM data only during the first session of the replication job. During subsequent replication job sessions, Veeam Backup & Replication will use the Virtual appliance or Network transport mode on the target side. The source side proxy will keep reading VM data from the source datastore in the Direct SAN access transport mode.
Veeam Backup & Replication writes VM data to the target datastore in the Direct SAN access transport mode only if disks of a VM replica are thick-provisioned. If disks are thin-provisioned, Veeam Backup & Replication will write VM data in the Network or Virtual appliance mode. By default, Veeam Backup & Replication replicates VM disks in the thin format. To write VM data to the target datastore in the Direct SAN access transport mode, select to convert VM disks to the thick format at the Destination step of the replication job wizard.
Direct SAN access is only used with thick-provisioned VMs for Veeam Replication. With thin-provisioned VMs, we use NBD or Virtual-Appliance mode instead of Direct SAN mode. You can convert a VM to thick-provisioned in the Destination step of the replication job wizard.
By foggy, What is not particularly clear to me in this paragraph; the Direct SAN access transport mode only if disks of a VM replica are thick-provisioned.
This is a VDDK limitation that supports direct SAN mode for thick-provisioned disks only (the same limitation applies to restore as well). The fact that only the initial job run can use this transport is due to incremental restore points are stored as snapshot files, which are always thin-provisioned.
