https://support.purestorage.com/Solutions/Linux/Linux_Reference/Linux_Recommended_Settings
https://www.dell.com/community/PowerPath/PowerPath-and-Linux-LVM/td-p/6599773
https://library.netapp.com/ecmdocs/ECMLP2748974/html/GUID-95A6E76F-C268-48A7-8E1C-D5B534355D6D.html
http://blog.chinaunix.net/uid-11676504-id-5823648.html
https://www.thegeeksearch.com/veritas-dynamic-multipathing-vxdmp-command-line-reference-cheat-sheet/
defaults {
user_friendly_names no
polling interval 5
fast_io_fail_tmo 5
dev_loss_tmo 120
checker_timeout 15
}
devices {
device {
vendor “DGC"
product “.*"
product_blacklist “LUNZ"
features “0″
hardware_handler “1 emc"
path_selector “round-robin 0″
path_grouping_policy group_by_prio
failback immediate
rr_weight uniform
no_path_retry 5
rr_min_io 1000
path_checker emc_clariion
prio emc
flush_on_last_del yes
}
}
run {
allocate channel c1 type disk;
backup archivelog from sequence 461797 until sequence 461798 thread 1 format ‘/backup/archivelog/arch_%U’;
backup archivelog from sequence 459596 until sequence 459597 thread 2 format ‘/backup/archivelog/arch_%U’;
}
run
{
catalog start with ‘/home/oracle/archivelog’;
allocate channel c1 type disk ;
restore archivelog from sequence 461797 until sequence 461798 thread 1;
restore archivelog from sequence 459596 until sequence 459597 thread 2;
}
1.) Contact the SAN administrator and make sure s/he knows how to present LUNs for Linux dm-multipath (may require different options at the SAN side than PowerPath; have him/her check the appropriate documentation from the SAN manufacturer)
2.) Unmount the data disks, shutdown any raw databases, and deactivate the VGs (vgchange -a n ).
umount /test
vgchange -a n testvg
3.) Remove and un-install PowerPath
Before you remove PowerPath, ensure the following:
Steps
● Ensure that no PowerPath devices are in use. Unmount all file systems from pseudo devices and ensure that none of the
logical volumes on volumes groups from pseudo devices are in use.
● Run the lsof command and ensure that none of the storage devices that are managed by the PowerPath are listed. If the
lsof command lists the processes along with opened PowerPath managed storage devices, then close such applications/
processes and ensure that PowerPath managed storage devices are not in use.
● Manually remove references to PowerPath pseudo devices from system configuration files. For example, /etc/fstab.
● If the LVM filter had previously been updated to PowerPath recommended filter when PowerPath was initially installed
and configured, restore the filter back to the default configuration. Pseudo devices are not available after PowerPath is
uninstalled.
rpm -qa | grep EMCpower.LINUX
rpm -ev EMCPower.LINUX-_
NOTE: In rare instances, if the PowerPath uninstall program displays a message saying that it could not unload the
emcp module, run the lsmod | grep emcp command to determine if any PowerPath modules are loaded on the host.
If so, restart the host after the uninstallation completes to unload the modules.
4.) Configure device-mapper-multipath and make the appropriate changes to the LVM configuration: with PowerPath, your LVM should be configured to use only PowerPath devices/prefer them over anything else. Now LVM should be configured to use dm-multipath devices instead.
Yes, filtering and/or the “preferred_names" setting in lvm.conf, if your Linux distribution has it.
# By default we accept every block device:
filter = [ “a/.*/" ]
#filter = [ “a|/dev/mapper/mpath.*|", “r|.*|" ]
5.) Run “multipath -v2″ to initialize the multipath configuration, then make sure the multipathd daemon is running and configured to start at boot time.
multipath -v2
pvscan (is this reqd?)
6.) Run “vgscan". It should automatically figure out that your VGs are now accessible through dm-multipath devices. Verify with commands like “pvs", “vgs". Make sure LVM uses dm-multipath devices, not /dev/sd* devices.
vgscan -vvvv
7.) Activate your VGs again (vgchange -a y). Mount filesystems; etc.
vgchange -a y testvg
mount /dev/testvg/testvol /test
8.) Remember to re-create your initrd, to remove the last traces of PowerPath & to include your new LVM and dm-multipath configurations. You might want to reboot to make sure the system can boot without issues.
mv /boot/initrd-2.6.18-194.17.1.el5.img /boot/initrd-2.6.18-194.17.1.el5.img.old
mkinitrd -v /boot/initrd-2.6.18-194.17.1.el5.img 2.6.18-194.17.1.el5
ivannexus 