Oracle RAC Temp File IO Test

Temp files are a special class of data files that are associated only with temporary tablespaces. Locally managed temporary tablespaces use temp files, which do not modify data outside of the temporary tablespace or generate any redo for temporary tablespace data. Because of this, they enable you to perform on-disk sorting operations in a read-only or standby database.

If IOPS performed on the temp files take too much time, administrators must be able to quickly and accurately identify the exact temp file to which read/write operations are most latent and the type of I/O operation that was performed on that file (i.e., whether a multiblock read/write or a single block read/write) when latency peaked. This will enable administrators to determine the course of action that needs to be taken to ensure that the I/O latency does not aggravate. This insight is provided by the Oracle RAC Temp File IO Test. This test automatically discovers the temp files on each node, and for each temp file reports the time taken to read and write single and multiple blocks of data in the file. This will point administrators to that temp file on which read/write operations take longer than normal. From this test, you can also infer when read/write latency is maximum – when reading a single block of data? Or when reading multiple blocks of data? When writing a single block of a data to the file? Or when writing multiple blocks of data to the file?

Target of the test : Oracle RAC

Agent deploying the test : An internal/external agent

Outputs of the test :One set of results for every temp file on each node in the target Oracle cluster being monitored.

Configurable parameters for the test
Parameter	Description
Test period	How often should the test be executed
Host	The host for which the test is to be configured.
Port	The port on which the server is listening.
SCAN Name	SCAN stands for Single Client Access Name, it is a feature used in Oracle RAC environments that provide a single name for clients to access any Oracle Database running in the cluster. You can provide SCAN as an alternative to IP/Host Name. If this parameter value is provided, it will be used for connectivity otherwise IP/Hostname will be used.
Service Name	A ServiceName exists for the entire Oracle RAC system. When clients connect to an Oracle cluster using the ServiceName, then the cluster routes the request to any available database instance in the cluster. By default, the Service Name is set to none. In this case, the test connects to the cluster using the ORASID and pulls out the metrics from that database instance which corresponds to that ORASID. If a valid service name is specified instead, then, the test will connect to the cluster using that Service Name, and will be able to pull out metrics from any available database instance in the cluster. To know the Service Name of a cluster, execute the following query on any node in the target cluster: select name, value from v$parameter where name =’service_names’
ORASID	The variable name of the oracle instance.
Username	In order to monitor an Oracle database server, a special database user account has to be created in every Oracle database instance that requires monitoring. A Click here hyperlink is available in the test configuration page, using which a new oracle database user can be created. Alternatively, you can manually create the special database user. When doing so, ensure that this user is vested with the select_catalog_role and create session privileges. The sample script we recommend for user creation (in Oracle database server versions before 12c) for eG monitoring is: create user oraeg identified by oraeg create role oratest; grant create session to oratest; grant select_catalog_role to oratest; grant oratest to oraeg; The sample script we recommend for user creation (in Oracle database server 12c) for eG monitoring is: alter session set container=<Oracle_service_name>; create user <user_name>identified by <user_password> container=current default tablespace <name_of_default_tablespace> temporary tablespace <name_of_temporary_tablespace>; Grant create session to <user_name>; Grant select_catalog_role to <user_name>; The name of this user has to be specified here.
Password	Specify the password of the specified database user.
Confirm Password	Confirm the Password by retyping it here.
SSL	By default, this flag is set to No, as the target Oracle cluster is not SSL-enabled by default. If the target cluster is SSL-enabled, then set this flag to Yes.
SSL Cipher	This parameter is applicable only if the target Oracle Cluster is SSL-enabled, if not, set this parameter to none. A cipher suite is a set of cryptographic algorithms that are used before a client application and server exchange information over an SSL/TLS connection. It consist of sets of instructions on how to secure a network through SSL (Secure Sockets Layer) or TLS (Transport Layer Security). In this text box, provide a comma-seperated list of cipher suites that are allowed for SSL/TLS connection to the target cluster. By default, this parameter is set to none.
Truststore File	This parameter is applicable only if the target Oracle Cluster is SSL-enabled, if not, set this parameter to none. TrustStore is used to store certificates from Certified Authorities (CA) that verify and authenticate the certificate presented by the server in an SSL connection. Therefore, the eG agent should have access to the truststore where the certificates are stored to authenticate and connect with the target cluster and collect metrics. For this, first import the certificates into the following default location <eG_INSTALL_DIR>/lib/security/mytruststore.jks. To know how to import the certificate into the truststore, refer toPre-requisites for monitoring Oracle Cluster. Then, provide the truststore file name in this text box. For example: mytruststore.jks. By default, none is specified against this text box.
Truststore Type	This parameter is applicable only if the target Oracle Cluster is SSL-enabled, if not, set this parameter to none.Specify the type of truststore that contains the certificates for server authentication in this text box. For eg.,JKS. By default, this parameter is set to the value none.
Truststore Password	This parameter is applicable only if the target Oracle Cluster is SSL-enabled, if not, set this parameter to none. If a Truststore File name is provided, then, in this text box, provide the password that is used to obtain the associated certificate details from the Truststore File. By default, this parameter is set to none.

Measurements made by the test
Measurement	Description	Measurement Unit	Interpretation
Multi block read time	Indicates the time taken by this file to service multiblock I/O requests on this node during the last measurement period.	Seconds/Read	Multiblock I/O read means reading multiple database blocks with a single operating system READ call. Typically, a database block is 8 KB. A single block read call results in one of these 8 KB blocks read from the datafile. Where a lot of data is to be read, it would be less efficient and more resource-intensive to read single blocks of data of 8KB each when the underlying I/O system is capable of reading say, 1 MB in one read. Oracle therefore issues a multiblock I/O and requests 1MB worth of block (128 8kb blocks) in one system READ call rather than 128 individual requests and therefore speeds up performance of the I/O requests. A very high value of this measure could indicate a bottleneck when processing multiblock read requests to a particular file. Compare the value of this measure across files to accurately identify that file from which multiple blocks of data were read from most slowly.
Single block read time	Indicates the time taken for singleblock reads from this file on this node during the last measurement period.	Seconds/Read	Typically, a database block is 8 KB. A single block read call results in one of these 8 KB blocks read from the datafile. Where a lot of data is to be read, it would be less efficient and more resource-intensive to read single blocks of data of 8KB each when the underlying I/O system is capable of reading say, 1 MB in one read. A very high value of this measure could indicate a bottleneck when processing single block read requests to a particular file. Compare the value of this measure across files to accurately identify that file from which a single block of data was read from most slowly.
Multi block write time	Indicates the time taken for singleblock writes to this file on this node during the last measurement period.	Seconds/write	In case of a singleblock write, a write call results in a single 8KB block being written into the file. If a lot of data is to be written to a file, single block writes can significantly increase I/O processing overheads and related resource costs. A very high value of this measure could indicate a bottleneck when processing single block write requests to a particular file. Compare the value of this measure across files to accurately identify that file to which a single block of data was written most slowly.
Single block write time	Indicates the time taken for multiblock writes into this file on this node during the last measurement period.	Seconds/write	Multiblock I/O write means writing multiple database blocks to a file with a single operating system WRITE call. A very high value of this measure could indicate a bottleneck when processing multiblock write requests to a particular file. Compare the value of this measure across files to accurately identify that file to which multiple blocks of data were written most slowly.
Sync read latency	Indicates the average latency for singleblock synchronous reads for single request since last test cycle on this file in this node.	Msecs/request	If there is a high latency for critical files, you may want to consider relocating these files to improve their service time.
I/O time	Indicates the time taken by IOPS on this file in this node during the last measurement period.	Seconds	A high value could indicate a processing bottleneck. Compare the value of this measure across files to identify that file, the reads and writes to which take the maximum time.