Unable to upload ISO to vSAN datastore from the vCenter web client or ESXi host web client

Products

• VMware vSAN

Issue/Introduction

Uploading files to a folder on the vSAN datastore fails.  There is no adequate free space on the vSAN datastore to accept the new files.  In the vmkernel.log, the following entries may be seen.

2025-05-23T16:19:02.201Z In(182) vmkernel: cpu41:2127751 opID=26ce9a5f)BC: 612: write to file.iso (f530 28 3 61409d47 ca06d89c ac78bffb 50bc0c44 2008c84 19 0 0 0 0 0) 1048576 bytes failed: No space left on device
2025-05-23T16:19:02.219Z In(182) vmkernel: cpu41:2127751 opID=26ce9a5f)BC: 612: write to file.iso (f530 28 3 61409d47 ca06d89c ac78bffb 50bc0c44 2008c84 19 0 0 0 0 0) 1048576 bytes failed: No space left on device

2025-05-23T16:19:02.200Z Wa(180) vmkwarning: cpu41:2127751 opID=26ce9a5f)WARNING: Res3: 7566: '########-####-####-####-############': [rt 1] No Space - did not find enough resources after second pass! (needed: 1, found: 0)
2025-05-23T16:19:02.219Z Wa(180) vmkwarning: cpu41:2127751 opID=26ce9a5f)WARNING: Res3: 7566: '########-####-####-####-############': [rt 1] No Space - did not find enough resources after second pass! (needed: 1, found: 0)

Environment

VMware vSAN (All Versions)

Cause

Sometimes it is necessary to store files in a folder on the vSAN datastore.  The contents of the folder are treated as user data and not vSAN objects.  The folder that is created on the vSAN has a hard 255 GB size limit.  Once that limit is reached, no new files can be copied or uploaded into the folder. 

Resolution

Workaround:

• A secondary folder can be created which would have adequate space to accept new files. 
• If there are any unnecessary files, those need to be moved or deleted to free up space in the original folder that is at full capacity. 
• To verify if a particular folder's contents has reached the maximum size, do the following:
  • Change directory to the folder: cd vmfs/volumes/vsan:-################-################/ISOs
  • If the ISOs friendly name is not visible from the vSAN root directory, use the folder UUID which can be obtained from the vCenter file browser to that folder.
  • If needed, change directory to the folder: cd vmfs/volumes/vsan:-################-################/1234567890123456-1234567890123456
  • Run: du -hx * | sort -rn    (to get the size of the files in the ISOs folder)

Additional Information

See also:  Unable to upload, copy, or create files in a VMware vSAN-backed datastore

Note: In vSAN 8.0U1, there is ability to expand the size of the namespace using the osfs-resize command. 

/usr/lib/vmware/osfs/bin/osfs-resize <full_path_to_the_namespace> <size_in_MB>

In the command, we are saying use osfs-resize against a custom namespace object and setting a size of 500 GB.

Custom namespace with custom size can be created using command osfs-mkdir:
/usr/lib/vmware/osfs/bin/osfs-mkdir -n <full_path_to_the_vSAN_Datastore> -s <size_in_MB>

Use the following for steps on how to expand a vSAN namespace.
Using PowerCLI to expand vSAN namespace for files larger than 255 gb