Dell PowerVault MD3000i Hardware Owner's Manual

Also see for PowerVault MD3000i: Getting started Tuning guide System installation guide User guide Information update

Contents

Dell PowerVault MD3000i Hardware Owner's Manual Manual pdf 45 page image

Using Your RAID Enclosure 45Snapshots are used to recover previous versions of files that have changedsince the snapshot was taken. Snapshots are implemented using a copy-on-write algorithm, which makes a backup copy of data the instant an erroroccurs. Data on a virtual disk is copied to the snapshot repository before it ismodified.Snapshots are instantaneous and take up less overhead than a full physicalcopy process.For further details on using snapshot virtual disks, see the MD StorageManager User’s Guide.Snapshot Repository Virtual DiskWhen you create a snapshot virtual disk, it automatically creates a snapshotrepository virtual disk. A snapshot repository is a virtual disk created in thestorage array as a resource for a snapshot virtual disk. A snapshot repositoryvirtual disk contains snapshot virtual disk metadata and copy-on-write datafor a particular snapshot virtual disk. The repository supports one snapshotonly.You cannot select a snapshot repository virtual disk as a source virtual disk oras a target virtual disk in a virtual disk copy. If you select a Snapshot sourcevirtual disk as the target virtual disk of a virtual disk copy, you must disable allsnapshot virtual disks associated with the source virtual disk.NOTICE: Before using the Snapshot Virtual Disks Premium Feature in a WindowsClustered configuration, you must map the snapshot virtual disk to the cluster nodethat owns the source virtual disk. This ensures that the cluster nodes correctlyrecognize the snapshot virtual disk.Mapping the snapshot virtual disk to the node that does not own the source virtualdisk before the Snapshot enabling process is completed can result in the operatingsystem misidentifying the snapshot virtual disk. This, in turn, can result in data lossor an inaccessible snapshot.For details on mapping the snapshot virtual disk to the secondary node, refer to theDell PowerEdge Cluster SE600W Systems Installation and Troubleshooting Guide onsupport.dell.com.