F5 ARX-VE, Planning Manual

Page: 32 / 64

Chapter 1
Site Planning
1 - 26
Refer to this chart to determine the limits for each ARX-appliance model.
Specifically, the chart shows the following maximums:
• Namespaces (shown as the maximum Volume Groups),
• Volumes,
• Managed-Volume Shares,
• Managed-Volume Files,
• Direct (or Presentation) Volume Shares, and
• Direct (or Presentation) Volume Attach Points.
Direct Volumes and NFSv3
NFSv3 contains 64-bit fields for each of the following file identifiers:
• the NFS file handle , and
• the back-end filer’s file ID .
An NFSv3 direct volume supports only 32 bits from its filers’ file handles.
Many NFS filers limit their file handles to this length for backward
compatibility with NFSv2.
An NFSv3 direct volume supports 30 bits or fewer in its filers’ File IDs.
Many popular NFS clients support a maximum of 32 bits total, and the
direct volume requires at least 2 of those bits (sometimes more) to
differentiate the file IDs from different back-end filers.
A managed volume does not have these limitations with respect to
Filehandles and File IDs.
The ARX Inter-Operability Matrix lists all of a direct volume’s supported
NFS filers and clients. This matrix is available from the ARX GUI, along
with this document; click the
Documentation link in the navigation panel
to access all of the ARX documentation.
Choosing Storage for Metadata
The ARX namespace metadata is data that contains the physical location of
files that the managed volumes are managing. It is used to find files and
directories on the physical file systems. Each managed volume in a
namespace maintains its own metadata for the file systems it manages.
Metadata is maintained on a per managed volume basis with a volume being
a collection of physical file systems. A namespace can consist of multiple
managed volumes and each volume can have a unique metadata location.
You can completely rebuild the ARX metadata at any time by re-scanning
the physical file systems. There is nothing proprietary in the metadata that
would prevent it from being recreated if it is lost or corrupted. For this
reason, F5 Networks does not recommend backing up the metadata.
F5 Networks provides utilities to fix most metadata inconsistencies, and a
rebuild utility to create a new metadata database.