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.
Since this allocated but unused space cannot be used by other applications, many
businesses face the need to buy more storage space.
As this need for more space grows, so does the cost.
The problem of wasted space, and the cost associated with it, is eliminated by moving
to thin provisioned storage. Thin provisioning is essentially the
act of using virtualization technology to give the appearance of more physical resources
than are actually available.
However, the principle of thin provisioning suffers from some unique drawbacks at
both the computational and storage levels.
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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?
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
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