Dell PowerFlex 4.5.x Administration Guide

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More about file systems

You can create, view, access, and manage file systems from the File > File Systems page.

A NAS server must be created before you can create a file system.

The NAS server must support the sharing protocol for which you are creating the file system. If you are creating a file system with NFS exports, the NAS server must support the NFS protocol. If you are creating a file system with SMB shares, the NAS server must support the SMB protocol.

You can choose to create SMB shares or NFS exports the first time you create the file system, or you can create SMB shares and NFS exports on a file system after it has been created.

Advanced settings for file systems that support SMB

These advanced settings can be configured for a file system that will be used for SMB shares.


Setting	Description
Sync Writes Enabled	When you enable the synchronous writes option for a Windows (SMB) or multiprotocol file system, the storage system performs immediate synchronous writes for storage operations, regardless of how the SMB protocol performs write operations. Enabling synchronous writes operations enables you to store and access database files (for example, MySQL) on storage system SMB shares. This option guarantees that any write to the share is done synchronously and reduces the chances of data loss or file corruption in various failure scenarios, for example, loss of power. This option is disabled by default. NOTE:The synchronous writes option can have a significant impact on performance. It is not recommended unless you intend to use Windows file systems to provide storage for database applications.
Oplocks Enabled	(Enabled by default) Opportunistic file locks (oplocks, also known as Level 1 opslock) enable SMB clients to buffer file data locally before sending it to a server. SMB clients can then work with files locally and periodically communicate changes to the storage system rather than having to communicate every operation over the network to the storage system. This is enabled by default for Windows (SMB) and multiprotocol file systems. Unless your application handles critical data or has specific requirements that make this mode or operation unfeasible, leaving the oplocks enabled is recommended. The following oplocks implementations are supported: Level II oplocks, which informs a client that multiple clients are accessing a file, but no client has yet modified it. A level II oplock lets the client perform read operations and file attribute fetches by using cached or read-ahead local information. All other file access requests must be sent to the server. Exclusive oplocks, which informs a client that it is the only client opening the file. An exclusive oplock lets a client perform all file operations by using cached or read-ahead information until it closes the file, at which time the server must be updated with any changes that are made to the state of the file (contents and attributes). Batch oplocks, which informs a client that it is the only client opening the file. A batch oplock lets a client perform all file operations by using cached or read-ahead information (including opens and closes). The server can keep a file opened for a client even though the local process on the client machine has closed the file. This mechanism curtails the amount of network traffic by letting clients skip the extraneous close and open requests.
Notify on Write Enabled	Enable notification when a file system is written to. This option is disabled by default.
Notify on Access Enabled	Enable notification when a file system is accessed. This option is disabled by default.

Settings for file systems that support NFS

Select Sys to allow users with non-secure NFS, or Secure NFS to mount and NFS export on the file system. If you are not configuring Secure NFS you must select this option.

If you are creating a file system with Secure NFS, then you can choose from the following options:

Kerberos to allow any type of Kerberos security for authentication (krb5/krb5i/krb5p).
Kerberos with Integrity to allow both Kerberos with integrity and Kerberos with encryption security for user authentication (krb5i/krb5p).
Kerberos with Encryption to allow only Kerberos with encryption security for user authentication (krb5p).


Access setting	Description
No Access	No access permitted to the storage resource or share.
Read-only	Hosts have permission to view the contents of the storage resource or share, but not to write to it.
Read/Write	Hosts have permission to read and write to the NFS datastore or share. NOTE:ESXI hosts must have Read//Write access in order to mount an NFS datastore using NFSv4 with Kerberos NFS owner authentication.
Read/Write, allow Root	Hosts have permission to read and write to the storage resource or share, and to grant revoke access permissions (for example, permission to read, modify and execute specific files and directories) for other login accounts that access the storage. The root of the NFS client has root access to the share. NOTE:Unless the hosts are part of a supported cluster configuration, a void granting Read/Write access to more than one host. NOTE:VMware ESXi hosts must have Read/Write, allow Root access in order to mount an NFS datastore using NFSv4 with NFS Owner:root authentication.
Read-only, allow Root (NFS Exports)	Hosts have permission to view the contents of the share, but not to write to it. The root of the NFS client has root access to the share.

Advanced properties for SMB shares

A file system must be configured to support SMB protocol before you can create a share.


Option	Description
Continuous Availability	Gives host applications transparent, continuous access to a share following a failover of the NAS server on the system (with the NAS server internal state saved or restored during the failover process). NOTE:Enable continuous availability for a share only when you want to use Microsoft Server Message Block (SMB) 3.0 protocol clients with the specific share.
Protocol Encryption	Enables SMB encryption of the network traffic through the share. SMB encryption is supported by SMB 3.0 clients and above. By default, access is denied if an SMB 2 client attempts to access a share with protocol encryption enabled. You can control this by configuring the RejectUnencryptedAccess registry key on the NAS Server. 1 (default) rejects non-encrypted access and 0 allows clients that do not support encryption to access the file system without encryption.
Access-Based Enumeration	Filters the list of available files and directories on the share to include only those to which the requesting user has read access. NOTE:Administrators can always list all files.
Branch Cache Enabled	Copies content from the share and caches it at branch offices. This allows client computers at branch offices to access the content locally rather than over the WAN. Branch Cache is managed from Microsoft hosts.
Offline Availability	Configures the client-side caching of offline files: Manual: Files are cached and available offline only when caching is explicitly requested. Programs and files opened by users: All files that clients open from the share are automatically cached and available offline. Clients open these files from the share when they are connected to it. This option is recommended for files with shared work. Programs and files opened by users, optimize for performance: All files that clients open from the share are automatically cached and available offline. Clients open these files from the share's local cache, if possible, even when they are connected to the network. This option is recommended for executable programs. None: Client-side caching of offline files is not configured.

SMB and NFS configuration details

The following table provides some details you will need when creating files systems, SMB shares, or NFS exports.


Option	Description
Name	The name provided for the export or share, along with the NAS server name is the name by which the hosts will access the export or share. NFS export, and SMB share names must be unique at the NAS server level per protocol. However, you can specify the same name for SMB shares and NFS exports.
Local path	The path to the file system storage resource on the storage system. This path specifies the unique location of the share on the storage system. SMB shares An SMB file system allows you to create multiple shares with the same local path. In these cases, you can specify different host-side access controls for different users, but the shares within the file system will all access common content. A directory must exist before you can create shares on it. Therefore, if you want the SMB shares within the same file system to access different content, you must first create a directory on the Windows host that is mapped to the file system. Then, you can create corresponding shares using Unisphere. You can also create and manage SMB shares from the Microsoft Management Console. NFS exports Each NFS export must have a unique local path. PowerFlex automatically assigns this path to the initial export created within a new file system. The local path name is based on the file system name. Before you can create additional exports within an NFS file system, you must create a directory to share from a Linux/UNIX host that is connected to the file system. Then, you can create a share from PowerFlex Manager and set access permissions accordingly.
SMB share path or export path	The path used by the host to connect to the share or export. PowerFlex Manager creates the export path based on the IP address of the file system, and the name of the export or share. Hosts use either the file name or the export path to mount or map to the export or share from a network host.

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