sidsanders wrote: » quick ref: Logical Unit Number - Wikipedia, the free encyclopedia lun can be a disk, tape, tape changer (robot arm), dvd device, etc. some of what you are talking about is lun masking, and perhaps fc zoning. lun masking is allowing an initiator (client machine you can say) see certain luns presented from a target (~ server, EMC would be the target) and not to any/all other initiators. emc uses storage groups to present luns to a host (or more than 1 for a cluster). fc zoning will allow the initiator to see a specific target -- note the target is then doing the authorization of what the initiator (client) can see. so the 2 items together are how a san will attempt to make things work without corrupting everyone's disk file systems. zoning -- lets an initiator see a target lun masking -- allows an initiator access to certain luns provided by the target vxfs, is a journaling file system. that is it uses a log to track fs changes. when machines go nutty, vxfs slices can recover faster than ufs/ext style fs's. vxfs also has in most cases: larger disk support, better inode support, advanced i/o features for db's, clustered version of vxfs, etc. vxfs isnt the only journaling fs out there however its one of the few that you will see on a few diff plats compared to ibm's jfs/jfs2.
