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Former Member
Nov 07, 2006 at 06:45 PM

LiveCache crash situation..

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Hi,

This is regarding SCM 4.0 and LiveCache 7.4.3 on AIX. SCM DB is Oracle and LiveCache DB is SAP-DB by default.

Our LiveCache was not available few days ago. I went to LC10 and found out that it was green but It would not let me to do anything and gave sql errors.

After few tries I had to restart to resolve the situation.

The situation was resolved after restart.

I went to LC10 - Prob Analysis - Db Analyser - Bottlenecks to analyse what happened. This is what I found -

| * W1 |Data cache hitrate (SQL Pages) 98.19%, 178668 of 9879774 accesses failed

| |CON: DC_Hit < 99 && ( PReads ) > MAX_IDLE_IO_ALL_DEVS

| |VAL: 98.19 < 99 && ( 178668 ) > 6772

ACT: In addition to enlarging the data cache (note the paging risk of the operating system), search for the cause of the high read activity. Frequently, individual SQL statements cause a high percentage of the total logical and physical read activit

DES: For a running database application the data cache hitrate should not be less than 99%, otherwise too much data has to be read physically. Data cache hitrates less than 99% for intervals of 15 minutes or more must be avoided.

| * W3 |OMS cache hitrate 97.39%, 178668 of 6849819 accesses failed

| |CON: OMS_Hit < 99 && ( OMS_Fails > MAX_IDLE_IO_ALL_DEVS )

| |VAL: 97.39 < 99 && ( 178668 > 6772 )

| * W3 |Log queue overflows: 2271

| |CON: LQ_Overflows > 0

| |VAL: 2271 > 0

| * I |Number of physical reads: 178668

| |CON: PReads > ( 4 * MAX_IDLE_IO_ALL_DEVS )

| |VAL: 178668 > ( 4 * 6772 )

| * I |Number of physical writes: 108089

| |CON: PWrites > ( 4 * MAX_IDLE_IO_ALL_DEVS )

| |VAL: 108089 > ( 4 * 6772 )

| * I |Garbage collector tasks activated 26 times, currently active: 0

| |CON: GC_Activities > 0 || ActivGarbColls > 0

| |VAL: 26 > 0 || 0 > 0

| * I |Garbage collection deleted 12 objects and 1600888 history objects, amount of history pages now: 176769

| |CON: GC_ObjDel > 0 || GC_HistReleased > 0

| |VAL: 12 > 0 || 1600888 > 0

| * I |backup activity: number of pages read 0, written 162176

| |CON: BackUpReadPg > 0 || BackUpWrittenPg > 0

| |VAL: 0 > 0 || 162176 > 0

| * W1 |LOGQUE1: collision rate 10.04%, 157938 collisions, 783 waits (0.05%), 1573152 accesses on region 24

| |CON: REGION_COLLISION_PERCENT[""] > MAXCPU * 2

| |VAL: 10.04 > 3 * 2

I have a feeling that it ran out of LiveCache and could not find enough room to write new information. That is why it was green but not available. The above logs also gives me impression that we have to increase the size of the LiveCache.

Please let me know if I am not thinking in right direction if I have missed anything here.

Your input will be greately appreciated.

Thank you.

sume