[scsi reservation] Reduce ack unit attention maximum duration on a de…

…vice (from 10s to 1s)

This patch reduces delay from 1s to 0.1s before next ack unit attention on a device
that reports unit attention.

The new maximum duration for a device is now 1s (10 retries with 0.1s delay)

opensvc/drivers/resource/disk/scsireserv/__init__.py

@@ -19,7 +19,6 @@ def __init__(self,
                  **kwargs):
         self.no_preempt_abort = no_preempt_abort
         self.devs = {}
-        self.preempt_timeout = 10
         self.prtype = '5'
         self.hostid = None
         self.peer_resource = peer_resource

opensvc/drivers/resource/disk/scsireserv/sg.py

@@ -7,6 +7,12 @@
 from utilities.proc import justcall, which
 from . import BaseDiskScsireserv
 
+# maximum number of unit attention to read from a device during ack_unit_attention()
+ACK_UNIT_ATTENTION_RETRY_MAX = 10
+
+# delay to wait before retry ack unit attention on a device that reports unit attention
+ACK_UNIT_ATTENTION_RETRY_DELAY = 0.1
+
 
 # noinspection PyUnusedLocal
 def driver_capabilities(node=None):
@@ -63,7 +69,7 @@ def ack_unit_attention(self, d):
             return 0
         if self.use_mpathpersist(d):
             return 0
-        i = self.preempt_timeout
+        i = ACK_UNIT_ATTENTION_RETRY_MAX
         self.set_read_only(0)
         while i > 0:
             i -= 1
@@ -78,7 +84,7 @@ def ack_unit_attention(self, d):
                 return 0
             if "Unit Attention" in out or ret != 0:
                 self.log.debug("disk %s reports 'Unit Attention' ... waiting" % d)
-                time.sleep(1)
+                time.sleep(ACK_UNIT_ATTENTION_RETRY_DELAY)
                 continue
             break
         if i == 0: