Abmr: test the automatic block Recovery feature and abmr test feature

Abmr: test the automatic block Recovery feature and abmr test feature

Abmr: test the automatic block Recovery feature

Reference Original:
ABMR: How to test Automatic Block Recover Feature (Doc ID 1266059.1)

Applicable:
Oracle Server-Enterprise Edition-Version: 11.2.0.1.0 and later [Release: 11.2 and later]
Information in this document applies to any platform.

Objectives:
This article first creates a bad block in datafile and then triggers the abmr feature.
As a pre-requirement for testing, you need to configure the master and slave databases of the dg and synchronize them normally.

Solution:
1. confirm that the block in the table contains data.
You can use the following query statement to translate rowid into file # And block #

Select rowid, dbms_rowid.rowid_block_number (rowid) blockno, dbms_rowid.rowid_relative_fno (rowid) fno
From test. test
Where rownum< 100
/

2. Using the block from the datafile identified file # using DD utility at OS level.
What is the above sentence? No cloud.
Dd if =/dev/zero of =/oradata/orcl/users. dbf count = 1 seek = 164 bs = 8192 conv = notrunc

3. Check whether the block is damaged.
Dbv file =/oradata/orcl/users. dbf blocksize = 8192

4. flush buffer cache on the master database to force data to be read again from the disk to the memory.
5. query the table again. No error is displayed and the queried data is valid.
Select * from test. test
Where dbms_rowid.rowid_block_number (rowid) = 164
And dbms_rowid.rowid_relative_fno (rowid) = 9
/

What is the soft recovery and hard recovery of diodes?

The interference produced by the output rectification diode has a reverse current at the end of the output rectification diode. The recovery time to zero is related to factors such as capacitance. A two-level tube that quickly restores the reverse current to zero is called a hard Recovery Characteristic diode. This diode produces high-frequency interference under the influence of transformer leakage and other distribution parameters, the frequency can reach dozens of MHz.

A Diode with a short reverse Recovery process is called a Fast Recovery Diode (Fast Recovery Diode ). High-frequency power electronic circuits require short reverse recovery time for fast recovery diodes, less charge for reverse recovery, and soft recovery.

All the pn-junction diodes store the charge in the form of less sub when conducting forward current. Shaozi injection is the mechanism of Conductivity Modulation, which leads to a reduction of Forward pressure drop (VF). In this sense, it is advantageous. However, when a reverse voltage is added to the on-going diode, a large number of minority carriers are stored in the base zone during the on-going process, therefore, it takes some time to completely extract or replace these minority carriers by the end, that is, to restore the reverse blocking capability.
After a period of time, this process is a reverse recovery process. The time used for this process is defined as the reverse recovery time (trr ).
Reference: www.chuandong.cn/...5.html

Why does the diode have reverse recovery?

The ideal diode stops when it is subjected to reverse voltage and there is no reverse current passing through. When the actual diode is being switched on, the charge in the PN junction is accumulated. When the diode is under the reverse voltage, the accumulated charge in the PN junction is released and a reverse recovery current is formed, the restoration time to zero is related to factors such as capacitance. Reverse recovery current will produce a strong high-frequency attenuation oscillation under the influence of transformer leakage and other distribution parameters. Therefore, the reverse recovery noise of the output rectification diode has become a major interference source in the switching power supply. The RC buffer can be connected at both ends of the diode to prevent reverse noise recovery.