Expert Oracle Exadata - Parent Directory

CHAPTER 10 EXADATA WAIT EVENTSExadata Wait Events in the Other and Idle ClassesThese are relatively minor events that occur primarily during startup and shut down of storage cells andfault conditions. You will probably not see them on normally functioning systems. There is oneexception to this, the cell smart flash unkeep event. Table 12.2 lists the “cell” wait events in the Otherclass along with their parameters. A separate section will cover cell smart flash unkeep.Table 10-2. Miscelaneous Other and Idle Class EventsEventcell manager cancel work requestcell worker online completioncell worker retrycell worker idleDescriptionThis event is not very informative, as all three of the parameters(P1, P2, P3) from the v$session_wait view are unused.This appears to be a startup event. The cell hash number iscontained in the P1 column of the v$session_wait view for thisevent. The P2 and P3 columns are unused.The cell hash number is contained in the P1 column of thev$session_wait view for this event. The P2 and P3 columns areunused.The P1, P2 and P3 columns from the v$session_wait view areunused in this idle event.cell smart flash unkeepThis event records the time spent waiting when Oracle must flush blocks out of Exadata Smart FlashCache. This can occur when a table that has a storage clause designating that it be pinned in ExadataSmart Flash Cache is truncated or dropped.Event MeaningTruncating and dropping tables doesn’t generally happen very often in most production systems (withsome notable exceptions) and therefore this wait event will probably not be seen very often. Here’s anexcerpt from a 10046 trace file showing the event:WAIT #4: nam='enq: RO - fast object reuse' ela= 393 name|mode=1380909062 2=65581 0=1 obj#=-1WAIT #4: nam='reliable message' ela= 1548 channel context=6712270872 channel handle=6696807856broadcast message=6741342984 obj#=-1 tim=1286218926420916WAIT #4: nam='enq: RO - fast object reuse' ela= 21027 name|mode=1380909 2=65581 0=1 obj#=-1WAIT #4: nam='ges message buffer allocation' ela= 2 pool=0 request=1 allocated=0 obj#=-1WAIT #4: nam='enq: RO - fast object reuse' ela= 159 name|mode=1380909057 2=65581 0=2 obj#=-1WAIT #4: nam='cell smart flash unkeep' ela= 336 cellhash#=379339958 p2=0 p3=0 obj#=-1WAIT #4: nam='cell smart flash unkeep' ela= 291 cellhash#=2133459483 p2=0 p3=0 obj#=-1WAIT #4: nam='cell smart flash unkeep' ela= 319 cellhash#=3176594409 p2=0 p3=0 obj#=-1WAIT #4: nam='cell smart flash unkeep' ela= 418 cellhash#=379339958 p2=0 p3=0 obj#=-1WAIT #4: nam='cell smart flash unkeep' ela= 1 cellhash#=2133459483 p2=0 p3=0 obj#=-1337