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frankdenneman Frank Denneman is the Chief Technologist for AI at VMware by Broadcom. He is an author of the vSphere host and clustering deep dive series, as well as a podcast host for the Unexplored Territory podcast. You can follow him on Twitter @frankdenneman

Error -1 in opening & reading the slot file error in storageRM.log (SIOC)

1 min read

The problem
Recently I noticed that my datastore cluster was not providing Latency statistics during initial placement. The datastore recommendation during initial placement displayed space utilization statistics, but displayed 0 in the I/O Latency Before column
01-Datastore-recommendations
The performance statistics of my datastores showed that there was I/O activity on the datastores.
02-Datastore-latency
However the SIOC statistics all showed no I/O activity on the datastore
03-SIOC-activity
The SIOC log file (storagerm.log) showed the following error:
Open /vmfs/volumes/ /.iorm.sf/slotsfile (0x10000042, 0x0) failed: permission denied
Giving UP Permission denied Error -1 opening SLOT file /vmfs/volumes/datastore/.iorm.sf/slotsfile
Error -1 in opening & reading the slot file
Couldn’t get a slot
Successfully closed file 6
Error in opening stat file for device: datastore. Ignoring this device
The following permissions were applied on the slotfile:
04-slotsfile-before
The Solution
Engineering explained to me that these permissions were not the default standards and default permissions are read and execute access for everyone and write access for the owner of the file. The following command sets the correct permissions on the slotsfile:
Chmod 755 /vmfs/volumes/datastore/.iorm.sf/slotsfile
Checking the permission shows that the permissions are applied:
05-slotsfile-after
The SIOC statistics started to show the I/O activity on the datastore
06-SIOC-activity-after
Before changing the permissions on the slotsfile I stopped the SIOC service on the host by entering the command: /etc/init.d/storageRM stop
However I believe this isn’t necessary. Changing the permissions without stopping SIOC on the host should work.
Cause
We are not sure what causes this problem and support and engineering are troubleshooting this error. In my case I believe it has to do with the frequent restructuring of my lab. vCenter and ESXi servers are reinstalled regularly, but I have never reformatted my datastores. I do not expect to see this error appear in stable production environments. Please check the current permissions on the slotsfile if Storage DRS does not show I/O utilization on the datastore. (VMs must be running and I/O metric on the Datastore cluster must be enabled of course)
I expect the knowledge base article to be available soon.

frankdenneman Frank Denneman is the Chief Technologist for AI at VMware by Broadcom. He is an author of the vSphere host and clustering deep dive series, as well as a podcast host for the Unexplored Territory podcast. You can follow him on Twitter @frankdenneman
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One Reply to “Error -1 in opening & reading the slot file…”

  1. Hi Frank, FYI i got the same issue even after deleting the .iorm.sf folder and restart the storageRM service. The file is recreated with -r-x–x— permission.

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