About VMFS system files overhead

Products

• VMware vSphere ESXi

Issue/Introduction

• There are hidden files in the root of any VMFS volume which start with a dot and end with the extension .sf
• Some free space is missing from a newly created VMFS datastore

Environment

VMware ESXi 4.0.x Embedded
VMware ESXi 4.1.x Embedded
VMware vSphere 5.5.x
VMware ESX 4.1.x
VMware vSphere 7.0.x
VMware vSphere ESXi 5.0
VMware vSphere ESXi 5.1
VMware ESXi 4.1.x Installable
VMware ESX Server 3.0.x
VMware ESX Server 3.5.x
VMware vSphere 6.x
VMware ESX 4.0.x
VMware ESXi 3.5.x Installable
VMware ESXi 4.0.x Installable
VMware ESXi 3.5.x Embedded

Resolution

These system files are indexes and descriptors of the files on the VMFS filesystem and cannot be deleted.

• They may take more space if you have a small block size (more addresses).
• They may take less space if you have a large block size (less addresses).
• They are metadata files that are created when the volume is first set up.
• They cannot be changed and cannot be deleted.
• They may grow over time but not significantly.

The VMFS-3 file system organizes all space on disk in collections of resources. There are four resource types managed by the VMFS-3 file system: Blocks, sub-blocks, pointer blocks, and file descriptors.

Resources are grouped together into collections called CLUSTERs and clusters can be further grouped together into CLUSTER GROUPS.

Each resource type is managed by one of several system files which are created during the file system bootstrap process:

• fbb.sf - file block bitmap.system file
• fdc.sf - file descriptor cluster.system file
• pbc.sf - pointer block cluster.system file
• sbc.sf - sub-block cluster.system file
• vh.sf - vmfs heartbeat.system file
• sdd.sf scsi device description.system file

The VMFS-5 file system uses one additional system file:

• pb2.sf - pointer block 2.system file

For more information, see VMware vSphere 5.x FAQ for VMFS-5 (2003813).

Additional Information

For translated versions of this article, see:

• 日本語: VMFS システム ファイル オーバーヘッドについて (2099308)
• 简体中文: 关于 VMFS 系统文件开销 (2111738)