Error: The ramdisk 'vsantraces' or 'vsantraceFailover' is full on vSAN ESXi host

Products

• VMware vSAN

Issue/Introduction

vSAN diagnostic traces store on a ramdisk by default. If a persistent scratch location is not configured, these traces exhaust the 300MB ramdisk capacity, leading to logging failures and monitoring alarms.

Symptoms:

• The vsantraceFailover partition or vsantraces partition is 100% full.
• vSAN diagnostic logging stops, resulting in loss of historical troubleshooting data.
• Logging in to the vSAN host through Log Insight or through the vSphere Web Client fails.
• vSphere Client: vSAN Virtual Objects fails to load with error "The request is rejected due to many pending requests."
• vSphere Client: vSAN Health / Healthcheck Error: "Unable to query vSAN Health information."
• Aria Operations: Error/Alarm: "ESXi: RAM disk / inode table is full."
• vdf -h shows the /vsantraces partition at 100% utilization.
• Supervisor upgrades failed where the spherelet fails to configure/remove due to the ramdisk issue
• ESXi host logging fails due to ramdisk full and need to reload syslog on ESXi host
                  /var/run/log/hostd.log on ESXi host shows Failed to connect to UDS socket /var/run/vmwSyslogCmd
• Log snippet from ESXi host vmkwarning.log shows:
  
  2026-09-29T20:16:32.169Z -WARNING vmkwarning - [host_name] cpu1:2131061) VisorFSRam: 251: Cannot extend visorfs file /vsantraces/vsantracesIODiag--2026-09-29T########--########-####-####-####-########.zst because its ramdisk (vsantraceFailover) is full.
  
  
• This can also be seen from vobd.log as well:
  
  2026-09-27T01:30:14.655Z -INFO vobd 2098072 [esx@4413 threadName="VisorfsCorrelator"] 3725011814us: [vob.visorfs.ramdisk.full] Cannot extend visorfs file /vsantraces/vsantraces--2026-09-27T01h27m35s673--6724b5b7-b14d-####-####-############.zst because its ramdisk (vsantraceFailover) is full.
  
  
• When ramdisk is full due to vsantraces this will also impact the collection of native trace logs.

 

Environment

• VMware vSAN

• VMware Cloud Foundation

Cause

The default vSAN trace configuration writes to a ramdisk partition. In ESXi 9.1.0, this is the vsantraceFailover partition. When a persistent scratch location is not defined on the ESXi host, these traces accumulate until they exhaust the limited 300MB capacity.

Resolution

Follow one of these options to resolve the issue. For known defects, subscribe to this article (Subscribe to a Broadcom knowledge article) to receive updates on fix status.

Option A: Limit vSAN trace size on local ramdisk If additional storage is not available, run these commands via SSH on all vSAN hosts to limit trace size:

1. For ESXi/vSAN 8.x and higher: 
   
   esxcli vsan trace set --urgentnumfiles=4 --urgentsize=8 --numfiles=10 --size=8
   
   
2. For ESXi/vSAN 7.x:

esxcli vsan trace set --urgentnumfiles=10 --urgentsize=10 --numfiles=10 --size=10

Option B: Redirect traces to a persistent scratch location

1. Create a host-specific folder on a valid VMFS datastore following documentation for Creating a persistent scratch location.
2. Redirect traces by running: 
   
   mkdir /vmfs/volumes/####/scratch/####/vsantraces/
   
   Followed by:

esxcli vsan trace set -f 10 -s 60 -p /vmfs/volumes/####/scratch/####/vsantraces/
   
   
3. Verify with:
   
   esxcli vsan trace get

   command to to make sure the "VSAN Traces Directory" is updated to new location.

Option C: Free up space immediately

1. Navigate to the traces directory: 
   
   cd /vsantraces
   
   
2. Delete old trace files to restore logging:
   
   rm vsantraces*20####*.zst

Note : Some cases, ESXi syslog needs to be reloaded 

esxcli system syslog reload

Additional Information

• vSphere 9.0 -- Set the Scratch Partition from the vSphere Client
• Identifying and Resolving Full Ramdisk Issues in ESXi Environments
• ramdisk full due to vsantraces and running vSAN File Services
• vCenter is repeatedly reporting "The ramdisk 'vsantraces' is full
• Ramdisk /var Partition Full and No vSAN Traces Available on ESXi Host