HP StorageWorks 70 HP StorageWorks Replication Solutions Manager 4.0.1 user gu - Page 442
Tru64 UNIX host volumes, Types
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• Demand allocated. The space allocated for the snapshot can automatically change from an initial minimum amount, up to the full capacity of the original (active) virtual disk. • Fully allocated. The space allocated for the snapshot is initially set to, and remains fixed at, the full capacity of the source (active) virtual disk. Demand-allocated snapshots When a snapshot is demand allocated, the storage system initially allocates only a small amount of space for the snapshot, just enough to store point-in-time information and pointers to data on the source. As data on the source is over-written, the controller increases the allocated space for the snapshot and copies the original (point-in-time) data from the source to the snapshot. If all the original data on the source is over-written, the controller increases the allocated space on the snapshot by an amount equal to the full size of the source. The size of the disk group in which the source and snapshot are located must be sufficient to handle increases in snapshot size, whenever the increases might occur. Insufficient space in the disk group can not only prevent the controller from increasing the space allocation, but it can also prevent writes to both the source and snapshot. Fully allocated snapshots When a snapshot is fully allocated, the storage system initially allocates an amount of space that is equal to the capacity of the source virtual disk, plus a small amount of space for point-in-time information and pointers to data on the source. As data is over-written on the source, the controller copies the original (point-in-time) data from the source to the snapshot. The amount of space allocated on the snapshot never changes. Once created, a fully allocated snapshot cannot run out of space. Tru64 UNIX host volumes General • The replication manager displays information about UFS, AdvFS host volumes and LSM logical volumes on enabled hosts. • In a host cluster, only the volumes on the cluster's enabled host are displayed. See enabled hosts. • Local replication of UFS and AdvFS host volumes is supported. Local replication of LSM logical volumes is not supported. See local replication. Mounting • The replication manager does not support mounting a Tru64 host volume in a subdirectory of /tmp. Types Virtual disks types reported by the replication manager: 442 Virtual disks