IC agent missing stats for a logical disk (4318873)

Some file system under the Disk details dashboard contain no data (see screenshots in attached file)

There are some missing statistics for one of the logical disks on a Linux host for:

- read/written

- reads/writes

Some logical disks have the above metrics but not the file system used metric which displays "There is No Data to Display"

The Logical Disk in question is a shared memory device, i.e. a memory-based (tmpfs) filesystem. The output of /proc/diskstats indicated that the OS (Linux) does not report read neither write statistics for this type of disks. This is because it is not a hardware device. In the Infrastructure Cartridge, memory-based filesystems will be excluded completely since we cannot determine much about them except the available space. This exclusion will alleviate the confusion we saw in this case.

Also, the IC agent reports free disk space if the OS lets the IC agent know about it. Hence for the Logical Disks that are not mounted (as they don't appear in the output of /proc/mounts), the OS does not determine the free space for them. 

 

Running the following commands,

1) df -h -l
2) lvdisplay
3) pvdisplay

on the Linux host have indicated which filesystems are local, which ones are defined as logical volumes and which one are physical volumes.

As the output of /proc/diskstats indicated that the OS  (linux) does not report read or write statistics for shared memory devices and neither determine free space for logical disks that are not mounted, the areas that are missing data in the graphs make sense.

Enhancement request (IC-1525) has been submitted to Development for consideration in a future release of Foglight Infrastructure Cartridge.