Dell manual Advanced features of the Dell PowerVault MD3000, Virtual disk snapshots, Storage

Storage

Figure 4. Dell Modular Disk Storage Manager GUI

connected to a host using Ethernet, or a combination of the two

•Display configuration information, add and remove storage arrays, and manage Simple Network Management Protocol (SNMP) and Simple Mail Transfer Protocol (SMTP) alert notifications

file from the CLI, administrators would enter the following command (where ipaddress is the IP address of the storage enclosure):

smcli ipaddress -f sample.scr;

Advanced features of the Dell

PowerVault MD3000

storage partitions. Virtual disk snapshot creation and virtual disk copy creation are premium fea- tures that must be purchased and enabled separately.

Virtual disk snapshots

Snapshots are persistent point-in-time images of a specific virtual disk that help eliminate the application downtime traditionally required to create system backups. They typically use less disk space and take less time to create than a physical copy.

Snapshots are implemented using the copy-on-first-write method: when virtual disk data needs to be modified, the original data is copied to the virtual disk snapshot cache before it is modified. The virtual disk on which the snapshot is based—the source virtual disk— must be a standard virtual disk in the storage array. Snapshots are typically created so that software such as a backup application can access them while the source virtual disk remains accessible to hosts.

Modular Disk Storage Manager supports application-aware snapshots, which are recom- mended for transaction-based applications where all transaction operations must be com- pleted for transactions to be valid. Application- aware snapshots coordinate with the application using the virtual disk to help ensure the consis- tency of snapshot data with application data. Once the snapshot has been created, the snap-

Figure 5 shows a script file called sample.scr	Administrators can use the PowerVault MD3000
that creates a 2 GB RAID-5 virtual disk called	and Dell Modular Disk Storage Manager to create
“Test” and sets its parameters. To run this script	virtual disk snapshots, virtual disk copies, and

//sample.scr

create virtualDisk diskGroup=1 RAIDLevel=5 userLabel="Test" owner=0 segmentSize=16 capacity=2GB;

set virtualDisk["Test"] mediaScanEnabled=false;

set virtualDisk["Test"] consistencyCheckEnabled=false; set virtualDisk["Test"] modificationPriority

=high;

Figure 5. Sample script for the Dell Modular Disk Storage Manager CLI

shot engine signals the application to resume normal processing. Microsoft Volume Shadow Copy Service (VSS) enables the creation of these snapshots.

Administrators can use the virtual disk snapshot feature to perform the following tasks:

•Create a complete image of data on a virtual disk at a particular point in time

•Provide quick, frequent, nondisruptive backups

•Test new versions of a database system with- out affecting actual data

•Enable snapshot virtual disks to be read, written, and copied

	DELL POWER SOLUTIONS	May 2007	Reprinted from Dell Power Solutions, May 2007. Copyright © 2007 Dell Inc. All rights reserved. Rev. 2.
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