![]() PCM PCM/friend/fcpother Path Control Module False After the ODM update, the newly discoverd disks will have vendor configured default values (like queue_depth, reserve_policy etc.) LIST THE MULTIPATCH DISK ATTACHED DRIVERIf host attachment contained non-MPIO definitions, then disks will be recognized as non-MPIO (like "EMC CLARiiON FCP RAID 1/0 Disk") and the vendor supplied driver needs to be installed for path management. (Usually only fail_over is possible but no round_robin or load_balancing.) After the ODM is updated, and the host attachment contained MPIO definitions, the device will be discovered as an MPIO device (for example EMC storage could look like "EMC MPIO FC disks") and one of the AIX PCMs can do the path management. Certification does not guarantee that all device capabilities can be used. A device will be discovered as an "MPIO other FC device" only if the device has been certified with one of the AIX default PCMs and no vendor-provided ODM definitions have been installed. LIST THE MULTIPATCH DISK ATTACHED INSTALLSDDPCM was very popular, but during the years the default AIX MPIO was also getting better and better, until it reached all the capabilities of SDDPCM, so IBM decided to withdraw SDDPCM from the market in 2020.įor example if we have a 3rd party storage (like Hitachi or EMC), and we don't install any additional packages, then probably AIX will detect disks as "Other FC SCSI Disk Drive". To solve this problem IBM created the SDDPCM package (for IBM storage), which was based on MPIO and it was capable for load-balancing. It made administration easier, but it was lacking some capabilites, for example load-balancing. It recognized that these paths belonged to the same LUN (hdisk), so only one hdisk device was created. Without installing any 3rd party or vendor filestes and without creating extra hdisks devices, the new AIX MPIO feature was capable of discovering multiple paths. ![]() Around 2002 AIX 5.2 has introduced a new feature called MPIO. It was capable of path failover and load balancing, but with the increased number of hdisks and vpath devices the maintenance was a bit complex. ![]() ![]() With SDD each path was called hdisk and on top of these a "super device" (vpath) has been created to do path management. At the end of the 90s and early 2000 SAN and FC technology got more popular and storage vendors (EMC, Hitachi, IBM.) came up with their own multipathing solutions. ![]()
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