Autoquiesce

6.10 LPAR mode z/VM guest KVM guest

Use the aq_mask sysfs attribute to control the DASD autoquiesce feature.

About this task

With autoquiesce, you can automatically stop DASD activity for the following cases:

DASD_EER_FATALERROR: 1 - any final I/O error
DASD_EER_NOPATH: 2 - no remaining paths for the device
DASD_EER_STATECHANGE: 3 - a state change interrupt occurred
DASD_EER_PPRCSUSPEND: 4 - the device is PPRC suspended
DASD_EER_NOSPC: 5 - there is no space remaining on an ESE device
DASD_EER_TIMEOUT: 6 - a certain amount of timeouts occurred
DASD_EER_STARTIO: 7 - the IO start function encountered an error

Use a value greater than 0 to enable the feature. The aq_mask attribute accepts an unsigned integer and the value is interpreted as a bitmask that defines the trigger events that lead to an automatic quiesce. The maximum value is 255. Bit 31 is reserved. Bit 0 is not used.

Examples

To deactivate autoquiesce, write 0 to the aq_mask attribute:
```
$ echo 0 > /sys/bus/ccw/0.0.1234/aq_mask
```
where 0.0.1234 is the device-bus ID of the DASD.
To enable autoquiesce for FATALERROR, NOPATH and TIMEOUT, giving bit mask 0000 0000 0000 0000 0000 0000 0100 0110 (= 70), issue:
```
$ echo 70 > /sys/bus/ccw/0.0.1234/aq_mask
```