Thin Provisioned Storage & VM Thin Provisioning
In the storage arena, thin provisioning is a fairly hot topic. Planning ahead for growth using traditional storage provisioning, system admins typically provide themselves with more storage space than is actually needed. This results in substantial inefficiencies as space is allocated, but often not used.
How do I better utilize my thin provisioned storage?
Some storage arrays include a feature permitting thin provisioning for their LUNs (logical unit number). This thin provisioning storage layer occurs below the virtual platform storage stack, and essentially means scalable datastores.
Thin provisioning at the datastore level has been the source of some concern for storage administrators with regards to recovery from over-provisioning. When virtual disks are deleted or copied away from a datastore, the array itself is not led to understand that those storage blocks are now free. You can see how this can lead to needless storage consumption.
vSphere 5 from VMware introduced a solution for this issue. The new vSphere Storage APIs for Array Integration (VAAI) for thin provisioning uses the SCSI UNMAP command to tell the storage array that space previously occupied by a VM can be reclaimed. This addresses one aspect of the issue with thin virtual machine growth.
Thin Provisioning is a method for optimizing utilization of available storage in a shared storage environment. It is a flexible manner to allocate space to systems, on a just-enough and just-in-time basis. It is a technique that applies to SANs, as well as virtual systems. One disadvantage in this technology is that deleted content is simply marked unused at the file system layer rather than zeroed out, causing a wasted space.
How to Reclaim Free Space on Thin Provisioned Virtual Disks?
With V-locity® I/O optimization software, we introduced a new Automatic Space Reclamation engine. This engine automatically zeroes out the no longer used free space within thin virtual disks, without taking them offline and with no impact on resource usage.
So what does this mean? Reclaiming the deleted makes virtual disk compaction easy. The thin virtual disks themselves are kept slimmed down within datastores, giving more control back to the storage admins governing provisioning.
The end result is that less storage is required, so instead of purchasing additional storage, your company can better utilize the storage they already have – saving you money.
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