Problem of Multipath ID confusion in Oracle ASM quorum disk

Some time ago received a response from the Shenzhen colleague, there is an Oracle cluster load is too high, in order to troubleshoot the problem, the system has restarted, but after the system restarts, 6 of the quorum disk is lost.

To find out why, log in to the system, execute df-h, found that the system's/boot partition became MPATHAP1, into the/dev/mapper directory, found more than mpathap1-3 three files. The initial judgment was due to the system's own Multipath software, which was viewed in the initial configuration/etc/multipath.conf, where the setting to mask the local disk was not added. Then manually by the document added, because the change is the system local partition, so the need to restart the system, found that after the restart, the problem is still, continue to try the/etc/fstab modification, the boot is directly bound to the/DEV/SDA, the result of system restart is not normal, only into single user modification. After attempting to uninstall the Multipath software, it is expected that the system will automatically revert to its original state, the result is not able to enter the system after reboot, need single user mode to enter, and reinstall the software. Enter/dev/to see if there is a sda1-3 discovery system that does not have this partition. Finally verify that the system has been tampered with by the Multipath software after the system reboot and is irreversible, if you can only reinstall the system if this problem is resolved. So before configuring multipathing, be sure to block out the local disk. and the probability of this problem is very small, because it has been restarted many times before, so be careful when configuring.

Through the execution of Multipath-ll found two wwid corresponding disk letter is chaotic, after looking at the time seems to really need to carefully, here delayed for a long time, because there are 15 disk characters, one is really very troublesome. In order to avoid the disk character confusion, modified the/etc/multipath.conf, for each wwid corresponds to a fixed drive letter.

Method:

multipath {

Wwid 36005076802810fb3000000000000007d

Alias MPATHF

}

And then execute

Multipath-f clear the configuration.

Service MULTIPATHD restart Restart services.

Multipath-v2 re-scan.

Multipath-ll

Now that the disk correspondence is resolved, the rest of the work is the DBA.

Appendix Add Method: Perform/lib/udev/scsi_id--page=0x83--whitelisted--DEVICE=/DEV/SDA view corresponding Wwid

Then add:

Blacklist {

Wwid 36234567890abcde01c6a312c0a867e33

}

This shields the local disk, rather than letting go of the default comment directly:

#blacklist {

# Wwid 0x6234567890abcde01c6a312c0a867e33

# devnode "^ (ram|raw|loop|fd|md|dm-|sr|scd|st) [0-9]*"

# devnode "^hd[a-z]"

#}

This shield off the optical drive external device, if the direct shielding device can also be written devnode "^sd[a-z]*"

Problem of Multipath ID confusion in Oracle ASM quorum disk