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February 16th, 2009 23:00
Emcpowerdevices under Veritas VCS
I was having emcpower devices in veritas VCS.
Just few days back I have migrated emcpower devices from one server to other server .
After adding new server to same old server's Storage Group I rebooted the new server .. Devices got visible to new server .. Initially on new server i saw OS native devices sda,sdb devices in "vxdisk -o alldgs" list output .
Then i exported the emcpower devices mapping from old server and imported on new server using "emcpadm" . Then ran "vxdctl enable" and now i can see emcpower devices in "vxdisk -o alldgs list" o/p.
It was obvious that initially i saw OS native devices sda,sdb devices in "vxdisk -o alldgs" list o/p but what does the emcpadm import_mapping has done which tells veritas that he has to show emcpowerdevices and not OS devices.
Can somebody eloberate what exactly happened during import_mapping ( other than renaming the powerdevices to device name in map file ) ?? What does it tell veritas. Does it create any device tree ??
According to my plan I thought i have to do "powervxvm install" and "powervxvm online" and that will tell Veritas that he has to use emcpowerdevices and not OS native devices.
My migration was sucessful but this is the question remain un-answered for me !!!
Just few days back I have migrated emcpower devices from one server to other server .
After adding new server to same old server's Storage Group I rebooted the new server .. Devices got visible to new server .. Initially on new server i saw OS native devices sda,sdb devices in "vxdisk -o alldgs" list output .
Then i exported the emcpower devices mapping from old server and imported on new server using "emcpadm" . Then ran "vxdctl enable" and now i can see emcpower devices in "vxdisk -o alldgs list" o/p.
It was obvious that initially i saw OS native devices sda,sdb devices in "vxdisk -o alldgs" list o/p but what does the emcpadm import_mapping has done which tells veritas that he has to show emcpowerdevices and not OS devices.
Can somebody eloberate what exactly happened during import_mapping ( other than renaming the powerdevices to device name in map file ) ?? What does it tell veritas. Does it create any device tree ??
According to my plan I thought i have to do "powervxvm install" and "powervxvm online" and that will tell Veritas that he has to use emcpowerdevices and not OS native devices.
My migration was sucessful but this is the question remain un-answered for me !!!
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dynamox
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February 17th, 2009 06:00
Thanks
ezirnhel
447 Posts
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February 17th, 2009 10:00
Thanks,
Erich
Conor
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February 17th, 2009 13:00
OK I'm thinking out loud...
I wonder if the Veritas used the descriptor area on the devices to recognise them (does it place it's own signature on the LUNs) and therefore recognised the native devices even before PP mappings were imported... once PP mappings were imported it updated itself to use the emcpower devices instead of native?
/speculation!
OnlySandy
63 Posts
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February 18th, 2009 01:00
Discriptor area is nothing but private region on the device .
But that doen't tell veritas to use OS device or Power devices ..
Yes one thing i forgot to tell that after seeing OS devices in vxdisk o/p and I checked the powerpath was not running so i started Powerpath demon on linux host . and checked the powermt display but it throw some powerpath error .Then i imported the mapping and vxdctl enable startes showing the emcpower devices in vxidks list o/p ..
Only thing that pinching me is that what import_mapping + vxdctl enable has done that veritas starts neglecting the OS devices and started using power devices ... If you want to exclude OS devices and start using the power devices then you have to use powervxvm commands thats what i knows..
Any more speculations ??