7.9. Managing Fast Path¶
Fast path is a feature that may boost Virtuozzo Storage read performance if node I/O is a bottleneck. In previous versions of Virtuozzo Storage, performance could be limited by node I/O being handled in a single thread in user space. In the current version of Virtuozzo Storage, fast path is enabled by default and I/O is handled using multi-threading in kernel space, which eliminates unnecessary context switches and improves performance.

If node I/O is a bottleneck, fast path may increase maximum node read performance up to 3 times in some cases.
Note
Typically, node I/O may be a bottleneck in clusters with cache on SSD or all-SSD setups.
Fast path is enabled by default. It is managed by the kdirect.enable
parameter in /etc/vstorage/vstorage-mount.conf
.
Ways to disable the feature differ depending on whether or not you use the GUI.
To disable fast path on a GUI-enabled deployment, do the following on each node:
Set ‘kdirect.enable’ to 0 in ‘/etc/vstorage/vstorage-mount.conf’.
Stop all VEs on the node or migrate them to another node using
prlctl migrate
or Virtuozzo Automator.Stop the
vstorage-ui-agent
service:# systemctl stop vstorage-ui-agent.service
Unmount the storage location:
# umount /vstorage/<cluster_name>
Start the
vstorage-ui-agent
service again:# systemctl start vstorage-ui-agent.service
The service will re-mount the storage location automatically.
Migrate all VEs back.
To disable fast path on a deployment without GUI, do the following on each node:
Set ‘kdirect.enable’ to 0 in ‘/etc/vstorage/vstorage-mount.conf’.
Stop all VEs on the node or migrate them to another node using
prlctl migrate
or Virtuozzo Automator.Unmount and re-mount the storage location:
# umount /vstorage/<cluster_name> # mount -a /vstorage/<cluster_name>
Migrate all VEs back.