![]() Can be imported on any supported UNIX platforms.Private regions aligned on 8KB boundaries.Allows disks to be recognized by all supported UNIX platforms.Allows diskgroups to be moved between different platforms.Newin 4.x Cross-Platform Data Sharing (CDS) Disk Format VxVM Disk Types/Formats Newin 4.x Starting with 4.0, always use cdsdisk format “auto:cdsdisk” Fewer disks means faster configuration changes.Enabled regions spread across controllers and enclosures.Number of disks based on total disks in diskgroup.Configuration information saved on selected disk.Objects information stored in the private region.Public region:……….application data storage.Private region: ………containing VxVM metadata.Identifies the disk to VxVM with a “unique” diskid.Initialize a disk before VxVM can use it.With DRL, only “in flight” regions need be made consistent.Eliminates the possibility of reading different data from different plexes during recovery.Make all plex contents consistent in background.Every block read by a user is rewritten to all plexes.Goal: Start volumes ASAP without loss of consistency.VxVM ensures the volumes are not left in indeterminate states (e.g., inconsistent mirrors).Detaches plex containing failing device (A detached plex remains associated with its volume, but does not participate in IO).Changes plex kstate to DETACH and updates klog.Marks disk with FAILING flag (Prevents allocation of new objects).Plexes must be kept consistent when IO errors occur.Certain operations require messages between nodes.Each node’s VxVM instance makes IO requests directly to disks.Resolve by relocating subdisks from busy disks.Identify “hotspots” at the object level.vxstat displays per-object IO statistics # vxstat vol vol-01 vol-02 c2t0d0s2-01 OPERATIONS BLOCKS AVG TIME(ms) TYP NAME READ WRITE READ WRITE READ WRITE vol my_11.1 4.4 pl my_vol-01 244 5 10.5 3.8 pl my_vol-02 1 1000 13.3 4.0 sd c2t0d0s2-01 1 1000 13.3 4.0.Object IO Path Example Application write my_vol my_vol my_vol-01 my_vol-02 my_vol-03 my_vol-04 d1-01 d2-01 d3-01 d4-01 B A d5 d6 d1 d2 d3 d4 Dynamic Multipathing Each object performs or requests actions required at its level.Volume is found in a hash from device number.vxconfigd loads the objects into the kernel.Device number identifies initial target object for each user request.vxconfigd creates devices in /etc/vx/dsk/.Users direct IO requests at volume or volume set.VxVM Objects Replication Volume Group Replication Link Volume Set Volume SRL DCO Plex Logonly Plex Snapshot Subcache Subdisk Logsubdisk DCO Volume Disk Media Cache Disk Access Info Cache Volume Dynamic Multipathing Storage Pool Solid foundation for advanced functionality.Group Manager, Product Management VERITAS Software Volume Manager Engineer Sean Derrington Sr. VERITAS VolumeManager TechnicalTalk S201/Best Practices Mike Root Sr.
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