HP P4000 9.0 HP StorageWorks P4000 SAN Solution User Guide - Page 190
Provisioning volumes, Full provisioning, Best practice for setting volume size
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Provisioning volumes Configure volume size based on your data needs, how you plan to provision your volumes, and whether you plan to use snapshots. The SAN/iQ software offers both full and thin provisioning for volumes. Table 39 Volume provisioning methods Method Full provisioning Thin provisioning Settings Volume size x Network RAID level factor = amount of space allocated on the SAN Volume size x Network RAID level factor >= amount of space allocated on the SAN Full provisioning Full provisioning reserves the same amount of space on the SAN as is presented to application servers. Full provisioning ensures that the application server will not fail a write. When a fully provisioned volume approaches capacity, you receive a warning that the disk is nearly full. Thin provisioning Thin provisioning reserves less space on the SAN than is presented to application servers. The SAN/iQ software allocates space as needed when data is written to the volume. Thin provisioning also allows storage clusters to provision more storage to application servers than physically exits in the cluster. When a cluster is over-provisioned, thin provisioning carries the risk that an application server will fail a write if the storage cluster has run out of disk space. The SAN/iQ software adds utilization and over-provisioned events as the cluster approaches 100% utilization. You can add capacity to the cluster or delete unneeded snapshots to accommodate additional volume growth. NOTE: Paying attention to the space utilization events on over-provisioned storage clusters is critical to prevent a write failure on a thin volume. Best practice for setting volume size Create the volume with the size that you currently need. Later, if you need to make the volume bigger, increase the volume size in the CMC and then expand the disk on the server. In Microsoft Windows, you expand a basic disk using Windows Logical Disk Manager and Diskpart. For detailed instructions, see "Changing the volume size on the server" on page 203. Planning data protection Data protection results from creating data redundancy for volumes on the SAN. Configure data protection levels, called Network RAID, when you create a volume. You can store two, three, or four mirrored copies of your data using Network RAID-10, Network RAID-10+1, or Network RAID-10+2. Network RAID-5 and Network RAID-6 store parity on multiple storage systems in the cluster. Under some workloads that write the data infrequently, Network RAID-5 and Network RAID-6 provide better 190 Provisioning storage