The Question is:
What does the "Trans Count" column on a $SHOW DEVICE <disk> mean? I had always
thought it meant the number of open files on the disk. I now have a Trans
Count of 2765 but a $SHOW DEV/FILE only shows 7 open files + INDEXF.SYS.
Also, from SDA it doesn't seem to be the number of channels from any of the
seven processes with one file open each.
The Answer is :
The SHOW DEVICE "trans count" (transaction count) is the number of
File Control Blocks (FCBs) associated with the device, and this
includes the number of files open on the disk, particularly including
any extension headers that might be present.
Please also ensure that you have the current mandatory ECO kits
installed on the system for the OpenVMS release in use, and please
move to a supported release -- there is the potential that this
large transaction count is artificially large, and was caused by
a (benign) problem within the file system that was found and fixed
in 1999. Please also ensure that your disks are not excessively
fragmented, as this will increase the numbers of extension headers
required for mapping the files.
A search engine that can provide you with lists of ECO kits based
on the ECO installation ratings is referenced in the OpenVMS FAQ.
Please get and please apply all mandatory kits.
As of this writing, OpenVMS V7.2-2 or V7.3-1 would be the logical
upgrade paths for this system.
Continuing with the SHOW DEVICE discussion, the SHOW DEVICE "mnt cnt"
(mount count) shows the number of times that a volume has been mounted,
both locally and throughout the cluster. Shared disk volumes can be
mounted multiple times on one node, or across multiple cluster members.
Batch jobs can use a MOUNT command to effectively prevent an existing
and previously-mounted disk volume from being dismounted until the
batch job is completed, for instance.
There is no user interface to the SHOW DEVICE mount count field; the
value is retrieved from an internal data structure. The sys$getdvi
(and f$getdvi) MOUNTCNT item returns the node-local mount count; the
number of times the volume is mounted on the local node.