Administrator Guide

Managing NAS Volumes
A NAS volume is a subset of the NAS pool in which you create SMB shares and/or NFS exports to make storage space available
to clients. NAS volumes have specific management policies controlling their space allocation, data protection, security style, and
so on.
You can either create one large NAS volume consuming the entire NAS pool or divide the NAS pool into multiple NAS volumes.
In either case you can create, resize, or delete these NAS volumes.
NAS volume availability depends on the availability of the Storage Centers. If a Storage Center is offline, storage center LUNs
will not be available for the FluidFS cluster, and access to the shares and/or exports will be lost. Correct the Storage Center
problem to resume service.
The following NAS features can be configured on each NAS volume:
● File security styles
● Quota rules
● Data reduction
● Snapshots
● NDMP backup
● Replication
File Security Styles
The Windows and UNIX/Linux operating systems use different mechanisms for resource access control. Therefore, you assign
each NAS volume a file security style (NTFS, UNIX, or Mixed) that controls the type of access controls (permission and
ownership) for the files and directories that clients create in the NAS volume.
A NAS volume supports the following security styles:
● UNIX – Controls file access using UNIX permissions. A client can change permissions only by using the chmod and chown
commands on the NFS mount point.
● NTFS – Controls file access by Windows permissions. A client can change the permission and ownership using Windows
(File Properties → Security tab).
● Mixed – Supports both NTFS and UNIX security styles. If you choose this option, the default security of a file or directory
is the last one set. Permissions and access rights from one method to another are automatically translated. (For example,
if a Windows administrator sets up file access permissions on a file through an SMB share, a Linux user can access the
file system through NFS and change all the file permissions.) Therefore, this option is not recommended in production
environments, except where you are not concerned about file access security and just need some NAS volume space to
store files temporarily.
Both NTFS and UNIX security styles allow multiprotocol file access. The security style determines only the method of storing
and managing the file access permissions information within the NAS volume.
If you need to access the same set of files from both Windows and UNIX or Linux, the best way to implement multiprotocol
access is by setting up individual user mapping rules or by enabling automatic user mapping. Ownership and access permissions
are automatically translated based on user mapping settings and file access credentials.
Modifying the file security style of a NAS volume affects only those files and directories created after the modification.
Thin and Thick Provisioning for NAS Volumes
In addition to the thin provisioning applied to the NAS pool, NAS volumes can be thin‑provisioned. With thin provisioning (the
default), storage space is consumed on the Storage Centers only when data is physically written to the NAS volume, not
when the NAS volume is initially allocated. Thin provisioning offers the flexibility to modify NAS volumes to account for future
increases in usage. However, because it is possible for the storage space used by the NAS volumes to exceed the Storage
Center space allocated to the NAS pool, you must monitor available capacity on the Storage Centers to ensure that the FluidFS
cluster always has sufficient free space available. You can also specify a portion of the NAS volume (reserved space) that is
dedicated to the NAS volume (no other volumes can take the space). The total reserved space of all NAS volumes cannot
exceed the available capacity of the NAS pool.
If a file is deleted from a thin-provisioned NAS volume, the free space as seen in Storage Manager increases. The freed-up
capacity is also visible and available to clients in the SMB shares or NFS exports. However, the Storage Center does not report
any capacity freed up in the NAS pool unless you enable the SCSI Unmap feature.
FluidFS Administration
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