CPFS protocol service scenario questions - Cloud Parallel File Storage

What protocols do CPFS protocol services support?

The Cloud Parallel File Storage (CPFS) protocol services support only NFSv3.

Am I charged for using CPFS protocol services?

General-purpose protocol services are free. Cache protocol services are a paid feature that provides memory cache capabilities and extra bandwidth. For more information about the fees for Cache protocol services, see Pricing.

What are the scenarios in which CPFS protocol services are applicable?

We recommend that you use CPFS protocol services in scenarios that require high-performance computing and video rendering based on Kubernetes. You can access a CPFS file system using the CPFS-POSIX client in scenarios that have high requirements on I/O or depend on MPI-IO, such as the design of electronic design automation (EDA) chips, meteorology, and computing in the oil industry.

What are the differences between the CPFS-POSIX client and the CPFS-NFS client?

Differences	CPFS-POSIX client	CPFS-NFS client
How to use	Install the Portable Operating System Interface (POSIX) client on a Linux-based ECS instance to which you want to mount a CPFS file system, and add the ECS instance to a CPFS-POSIX client cluster.	Install the lightweight Network File System (NFS) client on a Linux-based ECS instance to which you want to mount a CPFS file system, and run the `mount` command on the Linux operating system to mount the CPFS file system.
Required mount target	POSIX mount target.	Filesets or export directories of an NFS protocol service.
Support for Kubernetes	The Container Storage Interface (CSI) hostpath driver is supported.	The CSI NFS driver and CSI hostpath driver are supported.
Quorum node	Three ECS instances of low specifications are created as quorum nodes within your Alibaba Cloud account. The quorum nodes are used as client management nodes. You are charged for the created ECS instances.	You do not need to create a Quorum node.
Accessible space	The directory tree of the entire CPFS file system.	The directory tree of the mount target.
Performance	The CPFS-POSIX client provides high I/O performance in accessing data and metadata. We recommend that you use the CPFS-POSIX client to access small files whose size is smaller than 100 KiB. For more information, see Specifications.	The IOPS performance of the CPFS-NFS client in accessing data and metadata is lower than that of the CPFS-POSIX client due to the performance limits of the NFS protocol. We recommend that you use the CPFS-NFS client to access files whose size is 100 KiB or larger. For more information, see Specifications.
Access control	NFSv4 ACL	The CPFS-NFS client controls the read-only and read/write permissions based on IP addresses and CIDR blocks using NFSv4 ACLs.
Recommended scenarios	ECS	Kubernetes clusters, Container Service for Kubernetes (ACK) clusters, elastic container instances (ECIs), special versions of operating systems, and video rendering.

Do CPFS protocol services depend on POSIX mount targets?

No, CPFS protocol services and POSIX mount targets are separate channels. If you want to access a CPFS file system only using the NFS client, you do not need to create a POSIX mount target. You can create a protocol service and configure the export directory to access the CPFS file system. You can delete the POSIX mount targets that you no longer use.

Why do I fail to enable the protocol service feature?

The protocol service feature is supported in CPFS V2.3.0 and later versions. For more information about how to check the version number of a CPFS file system, see the "View the version number of a file system" section in the View the details of a file system topic.

Is there a difference between exporting filesets and directories using a CPFS protocol service?

Filesets and directories provide the same performance in I/O access. However, filesets can provide more features, such as the dataflow feature, which can meet more business requirements when used together with protocol services. We recommend that you export a fileset after it is created and use it for data access.

Can I change the specifications of a CPFS protocol service?

Yes, you can. To make the change, perform the following operations:

Change the protocol service type from general-purpose to cache
Important
- You cannot directly change a general-purpose protocol service to a cache protocol service. You must delete the general-purpose protocol service and create a cache one. Similarly, if you want to change the protocol service type from cache to general-purpose, you must delete the cache protocol service and create a general-purpose one. During the change, the service is interrupted. Reserve the change window before making the change.
- You need to regenerate the export folder.
1. Delete the general-purpose protocol service
  On the Protocol Service tab, find the protocol service that you want to delete. Click Delete in the Actions column, and then click OK.
2. Create a cache protocol service
  For more information, see the "Create a protocol service" section in the Manage protocol services topic.
Change the protocol service type from one cache type to another
1. On the Protocol Service tab, find the protocol service that you want to modify.
2. Click Modify in the Actions column and select another cache type.
3. After the modification is complete, click OK.

Can I change the bandwidth of a protocol service?

Yes, you can. Perform the following operations to make the change:

General-purpose
The bandwidth of general-purpose protocol services is the same as that of CPFS file systems. You can use the following methods to increase the bandwidth of general-purpose protocol services:
- Scale up CPFS file systems. For more information, see Scale up a CPFS file system.
- Change the specifications of protocol services. For more information, see the Change the protocol service type from general-purpose to cache section in this topic.
Cache Type
Cache protocol services support multiple specifications of bandwidth. You can select the appropriate bandwidth as needed. For more information, see the "Modify a protocol service" section in the Manage protocol services topic.
Note
It takes the system 2 to 5 minutes to apply the modification.

How do I monitor the performance of protocol services?

If you only need to configure threshold-triggered alert rules for monitoring metrics, you can use CloudMonitor to create alert rules. For more information, see Configure a basic alert rule.

To configure alert rules that are triggered based on the computing results of multiple metrics, you can use Hybrid Cloud Monitoring to create alert rules. For more information, see Configure an advanced alert rule.

Is the data stored in CPFS deleted if I delete a protocol service?

The data stored in CPFS is not affected if you delete a protocol service. However, you cannot access CPFS using the protocol service anymore. To access the original data, you must create a new protocol service or POSIX mount target.