ONTAP or Data ONTAP or Clustered Data ONTAP (cDOT) or Data ONTAP 7-Mode is NetApp's proprietary operating system used in storage disk arrays such as NetApp FAS and AFF (also known as NetApp Filer), ONTAP Select and Cloud Volumes ONTAP.
The short version is that it increases the number of NFS file system ids available. NFSv3 in ONTAP uses 32-bit file IDs by default. This allows a maximum number of 2,147,483,647 unsigned integers and matches up nicely with the 2 billion inode limit in a FlexVol.
A FlexGroup volume supports up to 400 billion files in a single FlexGroup volume so Netapp recommends using 64-bit identifiers. If this isn’t done there is a higher risk of FSID collisions which can cause a range of different issues because a single file will appear to exist in two locations.
The possible downside to this is that the version of Linux or Unix is used to access the flexgroup volume must support the 64-bit identifiers.
The short version is that it increases the number of NFS file system ids available. NFSv3 in ONTAP uses 32-bit file IDs by default. This allows a maximum number of 2,147,483,647 unsigned integers and matches up nicely with the 2 billion inode limit in a FlexVol.
A FlexGroup volume supports up to 400 billion files in a single FlexGroup volume so Netapp recommends using 64-bit identifiers. If this isn’t done there is a higher risk of FSID collisions which can cause a range of different issues because a single file will appear to exist in two locations.
The possible downside to this is that the version of Linux or Unix is used to access the flexgroup volume must support the 64-bit identifiers.