Dell Computer Drive manual Premium Feature-Snapshot Virtual Disks

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Premium Feature—Snapshot Virtual Disks

NOTE: If you ordered this feature, you received a Premium Feature Activation card shipped in the same box as your Dell PowerVault MD storage array. Follow the directions on the card to obtain a key file and to enable the feature.

A snapshot virtual disk is a point-in-time image of a virtual disk in a storage array. It is not an actual virtual disk containing data; rather, it is a reference to the data that was contained on a virtual disk at a specific time. A snapshot virtual disk is the logical equivalent of a complete physical copy. However, you can create a snapshot virtual disk much faster than a physical copy, using less disk space.

The virtual disk on which the snapshot is based, called the source virtual disk, must be a standard virtual disk in your storage array. Typically, you create a snapshot so that an application, such as a backup application, can access the snapshot and read the data while the source virtual disk remains online and accessible.

NOTE: No I/O requests are permitted on the source virtual disk while the virtual disk snapshot is being created.

Asnapshot repository virtual disk containing metadata and copy-on-write data is automatically created when a snapshot virtual disk is created. The only data stored in the snapshot repository virtual disk is that which has changed since the time of the snapshot.

After the snapshot repository virtual disk is created, I/O write requests to the source virtual disk resume. Before a data block on the source virtual disk is modified, however, the contents of the block to be modified are copied to the snapshot repository virtual disk for safekeeping. Because the snapshot repository virtual disk stores copies of the original data in those data blocks, further changes to those data blocks write only to the source virtual disk. The snapshot repository uses less disk space than a full physical copy, because the only data blocks that are stored in the snapshot repository virtual disk are those that have changed since the time of the snapshot.

Snapshot Virtual Disks

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Contents W . d e l l . c o m s u p p o r t . d e l l . c o m Dell PowerVault Modular Disk Storage Manager User’s GuideFebruary Contents Connecting the Serial Cable System Setup for Password Reset Viewing iSCSI Statistics and Setting Baseline Disk Groups and Virtual Disks Premium Feature-Snapshot Virtual Disks Troubleshooting Problems 101 Contents User Interface About This GuideSummary Tab Configure TabModify Tab ISCSI Tab Tools TabSupport Tab View online help View the event log Other Information You May NeedAbout Your Storage Array Access Virtual DiskOut-of-Band and In-Band Management Automatic Discovery of Storage Arrays Adding Storage ArraysManual Addition of a Storage Array Removing Storage Arrays Naming Storage ArraysInitial setup tasks include Setting Up Your Storage ArrayStorage Array To set, change, or remove a password for a storage array Setting a PasswordStorage Array Support Data Consider these guidelines when you create a password Resetting a PasswordPassword Guidelines Connecting the Serial CableMicrosoft Windows Operating Systems System Setup for Password ResetReset Password Configuring E-mail Alerts Configuring Alert NotificationsChanging Expansion Enclosure ID Numbers Storage Array Configuring Snmp Alerts Starting or Restarting the Host-Agent Software in Linux Starting or Restarting the Host-Agent Software in WindowsStorage Array Storage Array Using the iSCSI Tab Using iSCSIEntering Mutual Authentication Permissions Changing the iSCSI Target AuthenticationCreating Chap Secrets Valid Ascii Characters for Chap Secrets Space Using iSCSI Changing the iSCSI Target Discovery Changing the iSCSI Target IdentificationType the alias in the iSCSI target alias field and click OK Advanced iSCSI Host Ports Settings Configuring the MD3000i iSCSI Host PortsViewing or Ending an iSCSI Session Lowest priority defaultViewing iSCSI Statistics and Setting Baseline Statistics Edit, Remove, or Rename Host Topology Host Topology Actions Desired Action Using iSCSI Event Monitor Service Status area, click Start LinuxEnabling the Event Monitor Disabling the Event Monitor About Your Host Configuring Host AccessManual Configuration using SAS HBA Automatic ConfigurationClick Next Manual Configuration using iSCSIRemoving Host Access Creating a Host Group Host GroupsAdding a Host to a Host Group Moving a Host to a Different Host Group Removing a Host From a Host GroupRemoving a Host Group Host TopologyHost Context Agent Data Path Protection Create a virtual disk and map it to LUN Reboot the hostFailover with Red Hat Enterprise Linux About Your Host Disk Groups and Virtual Disks Creating Disk Groups and Virtual Disks Manual Configuration Disk Groups and Virtual Disks Disk Groups and Virtual Disks Hot Spare Drive Protection Automatically Configuring Hot SparesClick OK in the dialog box Manually Configuring Hot SparesCreating Host-to-Virtual Disk Mappings Host-to-Virtual Disk MappingModifying and Removing Host-to-Virtual Disk Mapping Changing Controller Ownership of the Virtual Disk Storage PartitioningDisk Group Expansion Disk Group and Virtual Disk ExpansionVirtual Disk Expansion Errors discovered by the media scan include Changing Media Scan SettingsStorage Array Media Scan Virtual Disk Service Microsoft Services Suspending the Media Scan Volume Shadow-Copy Service Disk Groups and Virtual Disks Premium Feature-Snapshot Virtual Disks About the Simple Path Creating a Snapshot Virtual Disk Using the Simple PathHost-to-Virtual Disk Mapping The default setting is Map now SMrepassist -ffilename-identifier Creating the Snapshot Using the Simple Path Snapshot Virtual Disks About the Advanced Path Creating a Snapshot Virtual Disk Using the Advanced PathSnapshot Virtual Disks SMrepassist -ffilename-identifier Creating the Snapshot Using the Advanced Path Snapshot Virtual Disks Source-virtual disk-name-sequence-number Specifying Snapshot Virtual Disk NamesSnapshot Repository Capacity Disabling a Snapshot Virtual Disk Re-creating Snapshot Virtual DisksPreparing Host Servers to Re-create a Snapshot Virtual Disk To disable a snapshot virtual diskRe-creating a Snapshot Virtual Disk Premium Feature-Virtual Disk Copy Reasons to use virtual disk copy include the following Creating a Virtual Disk Copy for an Mscs Shared DiskVirtual Disk Read/Write Permissions If you are using the target virtual disk for backup purposesVirtual Disk Copy Restrictions Preparing Host Servers to Create a Virtual Disk Copy Creating a Virtual Disk CopyChoose the target virtual disk Copying the Virtual DiskClick Next at the bottom Storage Array Performance During Virtual Disk Copy Setting Copy PriorityClick Yes to stop the virtual disk copy Stopping a Virtual Disk CopyRecopying a Virtual Disk To stop a virtual disk copy, complete the following stepsPreparing Host Servers to Recopy a Virtual Disk Recopying the Virtual Disk Removing Copy Pairs Virtual Disk Copy Downloading RAID Controller and Nvsram Packages Firmware DownloadsDownloading Both RAID Controller and Nvsram Firmware Downloading Non-redundant Mscs Nvsram Firmware Downloading Only Nvsram FirmwareDownloading Physical Disk Firmware Downloading EMM Firmware 100 Device Health Conditions Troubleshooting ProblemsRecovery Guru Storage Array Profile102 SMrepassist UtilityClick Browse Support Information Package103 Unidentified Devices Recovering from an Unidentified Storage Array105 Ping host-name-or-IP-address-of-the-hostTroubleshooting Inserting an EMM into an Expansion Enclosure Removing an EMM from the Expansion Enclosure107 Removing and Inserting Physical Disks MD3000 Maintenance Considerations108 109 110 111 IndexIndex 113 114