Prerequisites and limitations when adding file systems

Before adding or managing the file systems, you should understand the prerequisites and requirements. You should also refer to the related prerequisites and limitations when adding a cache device.

Network services

  • To add an SMB file system, you must have an Active Directory server defined to NAS Bridge.
  • To add an NFS file system, you must have either an Active Directory server or a DNS and NTP server defined. You normally configure these network services as part of deploying and initially configuring the NAS Bridge.

Cache devices

Each file system must be associated with a cache device. You can use either of these two approaches when assigning file systems to cache devices:

While the 1:1 model requires more hard disks, it provides a high degree of isolation among the file systems. This isolation improves performance and helps limit the impact of a cache device problem that could affect multiple file systems.

Therefore, the best practice is to use the 1:1 model and dedicate one cache device for each file system as follows:

StorageGRID buckets

To add file systems, you must have a StorageGRID system active and defined on the NAS Bridge. Defining or identifying the StorageGRID Gateway Node is normally done as part of initially configuring the NAS Bridge.

Every file system is placed in a single, dedicated StorageGRID S3 bucket. When adding a file system, NAS Bridge searches for the named bucket and uses it if found. If the bucket is not found, NAS Bridge creates it. When you add a file system, the named bucket might already exist for the following reasons:

When a NAS Bridge file system is removed, the bucket is not modified or deleted from the StorageGRID system. If you subsequently add a file system using the same bucket, the previous file data is retrieved from the bucket and exported through the new file system.

Attention: Although you can use an S3-compliant tool to view and retrieve NAS Bridge client data in the StorageGRID S3 bucket, data corruption or loss might occur if you attempt to delete, modify, or add objects to an S3 bucket used by NAS Bridge.
Attention: The first time you assign an S3 bucket to a file system, that file system is automatically assigned the role of Primary. If you assign the same bucket to file systems from multiple NAS Bridge virtual machines, each subsequent file system is assigned the role of Secondary and becomes read-only. The NAS Bridge assigns these roles to prevent data corruption or loss.
Attention: Make sure that any ILM rules associated with buckets handled by the NAS Bridge do not purge or delete objects. All delete operations are expected to be performed at the share/mount point level. In addition, make sure that ILM rules do not tier objects outside of StorageGRID, such as to cloud storage like Glacier.

Known limitations

There are some known limitations that apply when creating the file systems.

Setuid and Setgid bits
During a chown operation by a mounted NFS client, the setuid and setgid bits are not saved in the corresponding StorageGRID object. Instead, these bits are cleared as part of any operation that would normally modify them.
SMB file attributes
There are some SMB file attributes that are not accepted or saved by NAS Bridge. The following attributes are not supported:
File size limits for extended attributes
NAS Bridge limits any file system to 20 kilobytes (KB) per file for extended attributes. If an application tries to write more than 20KB into an extended attribute, an ENOSPC error is returned.
CIFS streams not supported
NAS Bridge does not support common internet filesystem (CIFS) streams.
CloudMirror incompatibility
Platform Services CloudMirror must not be used with NAS Bridge. NAS Bridge requires ordering guarantees and re-baselining, which are not available with CloudMirror.