Configure the POSIX connector
XCP NFS now supports the use of POSIX connectors to provide source and destination paths for data migration.
The following features are supported for POSIX connectors:
For POSIX file systems that support nanosecond
scancommand gets the full values (seconds and nanoseconds) and the
copycommand sets them
POSIX connectors are more secure than XCP with NFSv3 TCP sockets.
The path syntax for a POSIX connector is
file://<mounted path on linux>.
Set up a POSIX connector
To set up a POSIX connector, you must perform the following tasks:
Mount a source and a destination volume
Verify that the destination path has the necessary permission to write the data
A destination and a catalog are mounted in the following example:
root@scspr2395903001 ~]# findmnt -t nfs4 TARGET SOURCE FSTYPE OPTIONS /t/10.237.170.39_src_vol 10.237.170.39:/source_vol nfs4 rw,relatime,vers=4.0,rsize=65536,wsize=65536,namlen=255,hard,proto=t cp,timeo=600,retrans=2,sec=sys,clien /t/10.237.170.53_dest_vol 10.237.170.53:/dest_vol nfs4 rw,relatime,vers=4.0,rsize=65536,wsize=65536,namlen=255,hard,proto=t cp,timeo=600,retrans=2,sec=sys,clien /t/10.237.170.53_catalog_vol 10.237.170.53:/xcp_catalog nfs4 rw,relatime,vers=4.0,rsize=65536,wsize=65536,namlen=255,hard,proto=t cp,timeo=600,retrans=2,sec=sys,clien [root@scspr2395903001 ~]#
POSIX connectors access a source and destination volume by using the POSIX syntax
file://. In the above example, the source path is
file:///t/10.237.170.39_src_vol and the destination path is
You can manage the sample configuration of an XCP catalog shared by non-root users by creating a Linux group for XCP users. For non-root users, the following the permissions are required for Linux group users to perform migrations.
In the following sample output,
demo is the non-root user and
/mnt/xcp-catalog is the path where catalog volume is mounted:
sudo groupadd -g 7711 xcp_users sudo usermod -G xcp_users -a demo sudo chown -R :xcp_users /mnt/xcp-catalog sudo chmod -R g+w /mnt/xcp-catalog
The XCP catalog does not store data but it does store scan and copy file names, directory names, and other metadata. Therefore, it is recommended that you configure the catalog file system permissions for allowed users to give them the capability to secure the stored metadata.
Ownership (UID and GID)
When you are set up as a regular user, by default, a
copy command to a POSIX or NFS3 destination does not attempt to set the ownership (user ID (UID) and group ID (GID)). Setting the ownership is typically performed by an administrator. When user A copies files from user B, user A expects to own the destination. However, this is not the case when a root user copies the files. When a root user copies the files, the
-chown option changes the behavior so that a non-root
copy command with
-chown attempts to set the UID and GID.
Increase the maximum number of open file descriptors
For optimal performance and reliability, you can increase the maximum number of open file descriptors for the XCP user on all nodes.
Open the file by using the following command:
Add the following line to the file:
<username> - nofile 999999
root - nofile 999999
See Red Hat solutions for more information.