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Full Discussion: Disk Performance
Operating Systems Linux Disk Performance Post 302962159 by Peasant on Wednesday 9th of December 2015 03:45:00 AM
Old 12-09-2015
Check out the output of (output here is from one of my machines)..
Code:
ls -lart /dev/dm*
brw-rw----. 1 root disk253, 1 Nov 25 10:06 /dev/dm-1
brw-rw----. 1 root disk 253, 0 Nov 25 10:06 /dev/dm-0
brw-rw----. 1 root disk 253, 4 Nov 25 10:06 /dev/dm-4
brw-rw----. 1 root disk 253, 3 Nov 25 10:06 /dev/dm-3
brw-rw----. 1 root disk 253, 2 Nov 25 10:06 /dev/dm-2

Notice the MAJOR,MINOR numbers above
Code:
# dmsetup info
Name:              rootvg-tmp
State:             ACTIVE
Read Ahead:        256
Tables present:    LIVE
Open count:        1
Event number:      0
Major, minor:      253, 4
Number of targets: 1
..... # other output.

So rootvg-tmp coresponds with /dev/dm-4 device.

vgdisplay -v will provide output which physical volumes belong to which volume group.
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OCI_NEW_CONNECT(3)														OCI_NEW_CONNECT(3)

oci_new_connect - Connect to the Oracle server using a unique connection

SYNOPSIS
resource oci_new_connect (string $username, string $password, [string $connection_string], [string $character_set], [int $ses- sion_mode]) DESCRIPTION
Establishes a new connection to an Oracle server and logs on. Unlike oci_connect(3) and oci_pconnect(3), oci_new_connect(3) does not cache connections and will always return a brand-new freshly opened connection handle. This is useful if your application needs transactional isolation between two sets of queries. PARAMETERS
o $username - The Oracle user name. o $password - The password for $username. o $connection_string -Contains the Oracle instance to connect to. It can be an Easy Connect string, or a Connect Name from the tnsnames.ora file, or the name of a local Oracle instance. If not specified, PHP uses environment variables such as TWO_TASK (on Linux) or LOCAL (on Windows) and ORACLE_SID to determine the Oracle instance to connect to. To use the Easy Connect naming method, PHP must be linked with Oracle 10 g or greater Client libraries. The Easy Connect string for Oracle 10 g is of the form: [//]host_name[:port][/ser- vice_name]. From Oracle 11 g, the syntax is: [//]host_name[:port][/service_name][:server_type][/instance_name]. Service names can be found by running the Oracle utility lsnrctl status on the database server machine. The tnsnames.ora file can be in the Oracle Net search path, which includes $ORACLE_HOME/network/admin and /etc. Alternatively set TNS_ADMIN so that $TNS_ADMIN/tnsnames.ora is read. Make sure the web daemon has read access to the file. o $character_set -Determines the character set used by the Oracle Client libraries. The character set does not need to match the character set used by the database. If it doesn't match, Oracle will do its best to convert data to and from the database character set. Depending on the character sets this may not give usable results. Conversion also adds some time overhead. If not specified, the Oracle Client libraries determine a character set from the NLS_LANG environment variable. Passing this parameter can reduce the time taken to connect. o $session_mode -This parameter is available since version PHP 5 (PECL OCI8 1.1) and accepts the following values: OCI_DEFAULT, OCI_SYSOPER and OCI_SYSDBA. If either OCI_SYSOPER or OCI_SYSDBA were specified, this function will try to establish privileged connection using external credentials. Privileged connections are disabled by default. To enable them you need to set oci8.privileged_connect to On. PHP 5.3 (PECL OCI8 1.3.4) introduced the OCI_CRED_EXT mode value. This tells Oracle to use External or OS authentication, which must be configured in the database. The OCI_CRED_EXT flag can only be used with username of "/" and a empty password. oci8.privileged_connect may be On or Off. OCI_CRED_EXT may be combined with the OCI_SYSOPER or OCI_SYSDBA modes. OCI_CRED_EXT is not supported on Windows for security reasons. RETURN VALUES
Returns a connection identifier or FALSE on error. EXAMPLES
The following demonstrates how you can separate connections. Example #1 oci_new_connect(3) example <?php // create table mytab (mycol number); function query($name, $c) { echo "Querying $name "; $s = oci_parse($c, "select * from mytab"); oci_execute($s, OCI_NO_AUTO_COMMIT); $row = oci_fetch_array($s, OCI_ASSOC); if (!$row) { echo "No rows "; } else { do { foreach ($row as $item) echo $item . " "; echo " "; } while (($row = oci_fetch_array($s, OCI_ASSOC)) != false); } } $c1 = oci_connect("hr", "welcome", "localhost/orcl"); $c2 = oci_new_connect("hr", "welcome", "localhost/orcl"); $s = oci_parse($c1, "insert into mytab values(1234)"); oci_execute($s, OCI_NO_AUTO_COMMIT); query("basic connection", $c1); query("new connection", $c2); oci_commit($c1); query("new connection after commit", $c2); // Output is: // Querying basic connection // 1234 // Querying new connection // No rows // Querying new connection after commit // 1234 ?> See oci_connect(3) for further examples of parameter usage. SEE ALSO
oci_connect(3), oci_pconnect(3). PHP Documentation Group OCI_NEW_CONNECT(3)
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