ASM heartbeats detection-DelayedASMPSTheartbeats

Recently, the problem that the ASM disk dismount is continuously received and the error "Waited15secsforwriteIOtoPST" is reported. This is the unique heartbeat timeout detection of ASM. ASMinstance regularly checks whether each asmdisk can be normally reversed.

Recently, we have received the dismount of the ASM disk and the error "Waited 15 secs for write IO to PST". This is the unique heartbeat timeout detection of ASM, the ASM instance regularly checks whether each asm disk is normal.

Recently, we have received the dismount of the ASM disk and the error "Waited 15 secs for write IO to PST". This is the unique heartbeat timeout detection of ASM, the ASM instance regularly checks whether each asm disk can provide normal feedback. So I decided to make a small summary of this problem.

The following section describes the ASM diskgroup dismount with "Waited 15 secs for write IO to PST" (Doc ID 1581684.1:

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Generally this kind messages comes in ASM alertlog file on below situations,

Delayed asm pst heart beats on ASM disks in normal or high redundancy diskgroup,

Thus the ASM instance dismount the diskgroup. By default, it is 15 seconds.

By the way the heart beat delays are sort of ignored for external redundancy diskgroup.

ASM instance stop issuing more PST heart beat until it succeeds PST revalidation,

But the heart beat delays do not dismount external redundancy diskgroup directly.

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As described above, it can be understood as the following:

1. The ASM instance regularly checks the disk status of each disk group and whether the communication is normal;

2. This check only applies to normal and high redundancy modes. This error will not be encountered for external redundancy;

3. By default, the time-out period is 15 seconds. That is to say, if the 15 s disk group still does not respond to the ASM instance, the disk is dismounted.

Customers who encounter this problem all use fiber-optic network storage. This error occurs when the storage network is faulty. That is to say, when ASM regularly sends inspection information, if the disk does not provide feedback within 15 seconds, I think the disk is no longer accessible.

In response to this error, I tried to test in the test environment. Because the test environment is a VMware Virtual Machine, deleting a disk on the physical layer will not cause this problem. The reason is that after the disk on the same host is deleted abnormally, the ASM read operation will immediately return the system-level IO error, you do not need to wait for the timeout of the error "Waited 15 secs for write IO to PST.

Therefore, in summary, this error occurs only on the shared ASM disk, not on the local host, but on the Storage Network. The detection information sent by ASM cannot be reported in a timely manner, this error occurs. At this time, it may be the storage host, storage network, or even storage disk problems. anyway, I asm did not receive the confirmation information I needed. I think you have a problem, if the number of disks is too large to affect data integrity, then ASM will dismount the disk.

The error message "Waited 15 secs for write IO to PST" appears after 11.2.0.3.0 according to section 1581684.1. The document also describes how to manually modify the detection timeout time, which can be controlled by the parameter _ asm_hbeatiowait:

Alter system set "_ asm_hbeatiowait" = Scope = spfile sid = '*';

<需要重启asm crs来时修改生效。>

To confirm that this parameter is displayed after 11.2.0.3, I will query all the database versions. For details, refer to the following information:

==================================== 10.2 ======================== ==== SQL> select * from v $ version; BANNER -------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.5.0-ProdPL/SQL Release 10.2.0.5.0-ProductionCORE 10.2.0.5.0 ProductionTNS for Linux: version 10.2.0.5.0-ProductionNLSRTL Version 10.2.0.5.0-Production SQL> select ksppinm as "hidden parameter", ksppstvl as "value" from x $ ksppi join x $ ksppcv using (indx) where ksppinm like '\ _ %' escape '\' and ksppinm like '% undo %' order by ksppinm; hidden parameter value parameter ---------- _ INVALID parameter FALSE_asm_ausize parameter 3 hidden parameter value parameter -------- _ asm_instlock_quota parameter 0_asmsid asm21 rows selected. ==================================== 11.2.0.1 ====================== === sqlplus/as sysdbaConnected: oracle Database 11g Enterprise Edition Release 11.2.0.1.0-64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionsSQL> select ksppinm as "hidden parameter ", ksppstvl as "value" from x $ ksppi join x $ ksppcv using (indx) where ksppinm like '\ _ %' escape '\' and ksppinm like '% asm_hb %' order by ksppinm; hidden parameter value parameter _ asm_hbeatwaitquantum 2 ============================== 11.2.0.2 ======== =============$ sqlplus/as sysdbaConnected: oracle Database 11g Enterprise Edition Release 11.2.0.2.0-64bit ProductionWith the Partitioning, Oracle Label Security, OLAP, Data Miningand Real Application Testing optionsSQL> select ksppinm as "hidden parameter ", ksppstvl as "value" from x $ ksppi join x $ ksppcv using (indx) where ksppinm like '\ _ %' escape '\' and ksppinm like '% asm_hb %' order by ksppinm; hidden parameter value parameter _ asm_hbeatwaitquantum 2 is available after 11.2.0.3.0, that is to say, the ASM instance checks for disk timeout only after 11.2.0.3 ======================== 11.2.0.3 = ======================== sys @ R11203> select * from v $ version; BANNER orders Oracle Database 11g Enterprise Edition Release 11.2.0.3.0-64bit ProductionSQL> select ksppinm as "hidden parameter", ksppstvl as "value" from x $ ksppi join x $ ksppcv using (indx) where ksppinm like '\ _ %' escape '\' and ksppinm like '% undo %' order by ksppinm; hidden parameter valuehidden parameter value =------------------ _ asm_hbeatiowait 15_asm_hbeatwaitquantum 2 ============== 11.2.0.4 ====== ================== SQL> select * from v $ version; BANNER orders Oracle Database 11g Enterprise Edition Release 11.2.0.4.0-ProductionSQL> select ksppinm as "hidden parameter", ksppstvl as "value" from x $ ksppi join x $ ksppcv using (indx) where ksppinm like '\ _ %' escape '\' and ksppinm like '% undo %' order by ksppinm; hidden parameter value =--------- _ asm_hbeatiowait 15 <_ asm_hbeatwaitquantum 2 = ================ 12.1.0.1 =========================================$ sqlplus/as sysdbaConnected to: oracle Database 12c Enterprise Edition Release 12.1.0.1.0-64bit ProductionWith the Partitioning, OLAP, Advanced Analytics and Real Application Testing optionsSQL> select ksppinm as "hidden parameter ", ksppstvl as "value" from x $ ksppi join x $ ksppcv using (indx) where ksppinm like '\ _ %' escape '\' and ksppinm like '% asm_hb %' order by ksppinm; hidden parameter value between _ asm_hbeatiowait 15_asm_hbeatwaitquantum 2 after 12.1.0.2, the default value of this parameter is adjusted to 120 s ==================== 12.1.0.2 ========== ===============$ sqlplus/as sysdba Connected: oracle Database 12c Enterprise Edition Release 12.1.0.2.0-64bit ProductionWith the Partitioning, OLAP, Advanced Analytics and Real Application Testing optionsSQL> select ksppinm as "hidden parameter ", ksppstvl as "value" from x $ ksppi join x $ ksppcv using (indx) where ksppinm like '\ _ %' escape '\' and ksppinm like '% asm_hb %' order by ksppinm; hidden parameter value between _ asm_hbeatiowait 120_asm_hbeatwaitquantum 2

I hope this knowledge point will be helpful to you. In daily life, I often lament that this problem is very simple, but it is not sure. After the test, record it for query.