Gathering information about ESE DASD

Red Hat Enterprise Linux 8.6 LPAR mode z/VM guest KVM guest

Several sysfs attributes provide information about ESE DASDs.

Procedure

To examine the capacity of an ESE DASD, use the capacity sysfs attribute and its subentries.
The following examples use an ESE DASD with device-bus ID 0.0.95d0.
1. To see the logical size in cylinders, read the logical_capacity attribute, for example:
```
# cat /sys/bus/ccw/devices/0.0.95d0/capacity/logical_capacity
60102 
```
2. To see the currently used capacity in cylinders, read the space_allocated attribute, for example:
```
# cat /sys/bus/ccw/devices/0.0.95d0/capacity/space_allocated
27825
```
  For a non-ESE DASD, space_allocated is always the same as the logical_capacity.
3. To see total available space in cylinders, read the space_configured attribute, for example:
```
# cat /sys/bus/ccw/devices/0.0.95d0/capacity/space_configured
34103433
```
To examine the pool of extents in which the DASD is defined, use the extent_pool sysfs attribute, and its subentries.
For example, to see the pool ID, read the pool_id attribute:
```
# cat /sys/bus/ccw/devices/0.0.95d0/extent_pool/pool_id
0              
```
To see the extent size, use the extent_size attribute, which shows the size of the extent in cylinders. 21 or 1113 cylinders are possible:
```
# cat /sys/bus/ccw/devices/0.0.95d0/extent_pool/extent_size
1113  
```
For information about how to define the number of cylinders, see the documentation of your storage server.
To examine the utilization, use the cap_at_warnlevel and warn_threshold attributes.
For example, to see whether the available capacity has reached the warning level:
```
# cat /sys/bus/ccw/devices/0.0.95d0/extent_pool/cap_at_warnlevel
0  
# cat /sys/bus/ccw/devices/0.0.95d0/extent_pool/warn_threshold
15
```
where the value 15 means that the warning level is set to 85% for this extent pool on the storage server.
Should no space be left in the pool, the pool_oos attribute is set to 1. If so, all I/O traffic is stopped:
```
/sys/bus/ccw/devices/0.0.95d0/extent_pool/pool_oos
1
```
Otherwise the attribute shows 0.