Administrator Guide

Thick provisioning allows you to allocate storage space on the Storage Centers 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.
Managing NAS Volume Space
FluidFS maintains file metadata in i-node objects. FluidFS i-nodes are 4 KB in size (before metadata replication) and can contain
up to 3.5 KB of file data.
When a new virtual volume is created, a portion of it is allocated as i-node area. When a new file is created and there are no
free i-nodes left, an additional portion of the volume is allocated to the i-node area. When a file is deleted, however, the i-node
is marked as free (to make the allocation of new file i-nodes efficient) rather than returned to the free-space pool.
Free i-nodes are returned to the free-space of a volume only when the ratio between the free-space and the number of free
i-nodes becomes very low. When this situation occurs, a special background process is invoked which runs only until the ratio
crosses an internal threshold. The process does not run until all free i-nodes are returned to the free-space.
In deployment environments characterized by large amounts of small files, a massive deletion of small files does not fully reflect
in the amount of free-space in the volume. For example, if you filled a 100 TB volume with 70 TB of small files (leaving 30 TB
free-space) and then deleted 50 TB of them, the amount of free-space would likely not increase much. However, as long as the
workload remains small-file oriented, the system reuses the free i-nodes and does not consume from the free-space. Creating
some large files requires more space and eventually return a good portion of the free i-nodes to the free space.
Choosing a Strategy for NAS Volume Creation
When you define multiple NAS volumes, you can apply different management policies — such as data reduction, data
protection, file security style, and quotas — based on your needs.
Consider the following factors to help choose the right strategy based on your environment’s requirements:
● General requirements
○ NAS volumes can be created, resized (increased or decreased), or deleted.
○ A single NAS volume can contain NFS exports, SMB shares, or a combination of NFS exports and SMB shares.
○ The minimum size of a NAS volume is 20 MB. (If the volume has already been used, the minimum size should be more
than the used space or reserved space, whichever is highest.)
● 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-based clients and NTFS security style for Windows-based clients. This separation
enables the administrator to match the security style with business requirements and various data access patterns. The
security style can also be set to Mixed, which supports both POSIX security and Windows ACLs on the same NAS volume.
When a NAS volume is created, the default file permissions is set to Windows. The settings should be edited immediately
after the NAS volume has been created.
● Quotas – Different quota policies can be applied to different NAS volumes, allowing the administrator to focus on managing
quotas when it is appropriate.
● Replication schedules – Different volumes can have different replication schedules and policies.
● Auditing SACL SMB Access – Different volumes can have different policies for handling the auditing of SACL SMB
accesses.
Examples of NAS Volume Creation
This section includes examples that show how NAS volumes can be created to meet the needs of an organization with the
departments and NAS volume requirements described in the following table.
Department
Security
Style
Snapshots Replication NDMP
Backup
Number of
SMB/NFS
Clients
Read/Write
Mix
Hourly
Change % of
Existing
Data
Post
Production
UNIX Hourly No Weekly 20 20/80 1%
396 FluidFS Administration