i am going to list couple of emc commands, that could be usefull in servers connected to EMC Symmetrix.Removing dead paths:When dead disk is found while running 'powermt display dev=all', and offcourse after confirmin no issues from SAN,run the below commands to fix.# powermt restore -->To delete any dead paths, and to reconfigure them again:# powermt reset # powermt configOr you could run:# powermt checkRemoving disk reservation lock:Sometimes disk resevation is set on the EMC disks hdiskpower during system crash, or when system failovers. Disk reserves couldbe released by/usr/lpp/EMC/Symmetrix/bin/emcpowerreset fcs0 hdiskpower121Also recently i have seen issues in few Aix 5.x and 6.1 versions, ECC agents holding disks. Sometimes when no gatekeeper device are assigned and sym tends to use them as Gatekeeping device. All these results in PV missing seen in Volume groups. In these cases stop ECC agents. Kill all the process that are accessing the disks.(fuser /dev/hdiskpower). Issue should have fixed after that.Installing Regisration key for powerpath:#powermt check_registrationThere are no license keys now registered.#powermt versionEMC powermt for PowerPath (c) Version 5.1 SP 1 (build 13)#emcpreg -install=========== EMC PowerPath Registration ===========Do you have a new registration key or keys to enter?[n] yEnter the registration keys(s) for your product(s),one per line, pressing Enter after each key.After typing all keys, press Enter again.Key (Enter if done): BOPZ-MB4K-7FBM-Q6OL-MU96-YDRR1 key(s) successfully added.Key successfully installed.Key (Enter if done):1 key(s) successfully registered.#powermt check_registrationKey BOPZ-MB4K-7FBM-Q6OL-MU96-YDRR Product: PowerPath Capabilities: All#powermt config#powermt display dev=all Performing ODM Cleanup:1. Before making any changes, collect host logs to document the current configuration. At a minimum, save the following:inq, lsdev -Cc disk, lsdev -Cc adapter, lspv, and lsvg2. Shutdown the application(s), unmount the file system(s), and varyoff all volume groups except for rootvgDo not export the volume groupsvaryoffvgCheck with.....lsvg -o (confirm that only rootvg is varied on)If No PowerPath, Skip all steps with power names3. For CLARiiON configuration, if Navisphere Agent is running, stop it/etc/rc.agent stop4. Remove paths from Powerpath configurationpowermt remove hba=all5. Delete all hdiskpower deviceslsdev -Cc disk -Fname | grep power | xargs -n1 rmdev -dl6. Remove the PowerPath driver instancermdev -dl powerpath07. Delete all hdisk devices- for Symmetrix devices, use this command:lsdev -CtSYMM* -Fname | xargs -n1 rmdev -dl- for CLARiiON devices, use this command:lsdev -CtCLAR* -Fname | xargs -n1 rmdev -dl8. Confirm with lsdev -Cc disk that there are no EMC hdisks or hdiskpowers9. Remove all Fiber driver instancesrmdev -Rdl fscsiX ---> X being driver instance number i.e. 0,1,2, etc.10. Verify through lsdev -Cc driver that there are no more fiber driver instances (fscsi)11. Change the adapter instances in Defined statermdev -l fcsX ---> X being adapter instance number i.e. 0,1,2, etc.12. Create the hdisk entries for all EMC devicesemc_cfgmgr or cfgmgr -vl fcsx ---> x being each adapter instance which was rebuiltSkip this part if no PowerPath.13. Configure all EMC devices into PowerPathpowermt config14. Check the system to see if it now displays correctlypowermt displaypowermt display dev=alllsdev -Cc disk