Dell PowerVault NX3500 - Manual (Page 90)

If you need to access the same set of files from both Windows and UNIX/Linux, the best way to
implement multi
‐protocol 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 files and directories created after the
modification.
Thin and Thick Provisioning for NAS Volumes
Although PowerVault NAS pool is thickly provisioned to the FluidFS system, NAS volumes can be thin ‐
provisioned. With thin ‐provisioning (the default), storage space is consumed on the MD Arrays(s) only
when data is physically written to the NAS volume, not when the NAS volume is initially created. Thin ‐
provisioning allows NAS volumes to account for future increases in usage. However, because it is possible
for the storage space allocated by the NAS volumes to exceed the storage space allocated to the NAS
pool, ensure that you monitor available capacity on the MD array(s) to ensure that the FluidFS system
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 FluidFS Manager
increases. The freed up capacity is also visible and available to clients in the CIFS shares or NFS exports.
However, the MD array does not report any capacity freed up in the NAS pool.
Thick provisioning allows you to allocate storage space on the MD array(s) statically to a NAS volume (no
other volumes can take the space). Thick provisioning is appropriate if your environment requires
guaranteed space for a NAS volume.
Choosing a Strategy for NAS Volume Creation
Choosing to define multiple NAS volumes enables you to apply different management policies, such as
data reduction, data protection, security style, and quotas, based on your storage needs.
Consider the following factors to help choose the right strategy based on your environment’s
requirements:
• General requirements  NAS volumes can be easily created, resized (increased or decreased) based
on the system capacity, or deleted.
– NAS volumes can be easily created, resized (increased or decreased) based on the system
capacity, or deleted.
– A single NAS volume can contain NFS exports, CIFS shares, or a combination of NFS exports and
CIFS shares.
– The minimum size of a NAS volume is 20 MB (or if the NAS volume has already been used, the
minimum size is the stored data).
• Business requirements: A company or application requirement for separation or for using a single
NAS volume must be considered. NAS volumes can be used to allocate storage for departments on
demand, using the threshold mechanism to notify administrators when they approach the end of their
allocated free space.
• Data reduction: Each NAS volume can have a dedicated data reduction policy to best suit the type of
data it stores.
• Snapshots: Each NAS volume can have a dedicated snapshot scheduling policy to best protect the
type of data it stores.
• Security style: In multiple protocol environments, it might be beneficial to separate the data and
define NAS volumes with UNIX security style for UNIX/Linux ‐ased clients, and NTFS for Windows‐ased
clients. This enables the administrator to match the security style with business requirements and
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