vsphere-esxi-vcenter-server-55-storage-guide

vSphere StorageFile-Based (VMFS) SolutionWhen you use an ESXi system in conjunction with a SAN, you must decide whether file-based tools aremore suitable for your particular situation.When you consider a file-based solution that uses VMware tools and VMFS instead of the array tools, beaware of the following points:• Using VMware tools and VMFS is better for provisioning. One large LUN is allocated andmultiple .vmdk files can be placed on that LUN. With an RDM, a new LUN is required for each virtualmachine.• Snapshotting is included with your ESXi host at no extra cost.• Using VMFS is easier for ESXi administrators.• ESXi administrators who use the file-based solution are more independent from the SAN administrator.Third-Party Management ApplicationsYou can use third-party management applications in conjunction with your ESXi host.Most SAN hardware is packaged with storage management software. In many cases, this software is a webapplication that can be used with any web browser connected to your network. In other cases, this softwaretypically runs on the storage system or on a single server, independent of the servers that use the SAN forstorage.Use this third-party management software for the following tasks:• Storage array management, including LUN creation, array cache management, LUN mapping, andLUN security.• Setting up replication, check points, snapshots, or mirroring.If you decide to run the SAN management software on a virtual machine, you gain the benefits of running avirtual machine, including failover using vMotion and VMware HA. Because of the additional level ofindirection, however, the management software might not be able to see the SAN. In this case, you can usean RDM.NOTE Whether a virtual machine can run management software successfully depends on the particularstorage system.SAN Storage Backup ConsiderationsHaving a proper backup strategy is one of the most important aspects of SAN management. In the SANenvironment, backups have two goals. The first goal is to archive online data to offline media. This processis repeated periodically for all online data on a time schedule. The second goal is to provide access to offlinedata for recovery from a problem. For example, database recovery often requires retrieval of archived logfiles that are not currently online.Scheduling a backup depends on a number of factors:• Identification of critical applications that require more frequent backup cycles within a given period oftime.• Recovery point and recovery time goals. Consider how precise your recovery point needs to be, andhow long you are willing to wait for it.• The rate of change (RoC) associated with the data. For example, if you are usingsynchronous/asynchronous replication, the RoC affects the amount of bandwidth required between theprimary and secondary storage devices.32 VMware, Inc.