vSphere 5 storage enhancements

Doyle on a Riemann Sphere by fdecomite (cc) (from Flickr)
Doyle on a Riemann Sphere by fdecomite (cc) (from Flickr)

Twitter was all abuzz yesterday about the recent VMware vSphere 5 announcement. Although there were quite a few changes that came out, the ones of most interest to me were all in the data storage arena:

  • DAS storage appliance – VMware vSphere 5 now has a virtual machine that can take server DAS and offer a shared storage service to other VMs.  The storage appliance is only available for the Essentials+ and below licensing options and is restricted to a three physical ESX server environment.
  • Host based replication service – vSphere 5 now offers a software only replication option to support disaster recovery.  The host-based replication service is not considered high-bandwidth and will not compete with storage or other hardware replication products but can be used to support heterogeneous storage replication.
  • Storage DRS – For vSphere 5 Enterprise edition and above once storage pools have been defined, Storage DRS can migrate VMs to other storage within a pool to automatically load balance IO activity.
  • Storage performance guarantees – For Enterprise edition and above vSphere 5 can provide a QOS capability for IO activity allowing designated, high priority VMs to gain preferential access to IO queues and such so that they perform better in a noisy, mixed environment.
  • IO performance improvements – VMware claims a 4X improvement in storage throughput with vSphere 5.
  • Linked clones – VMware now offers a storage option that can chain two read-writeable copies of a VMDK together and only store the changes needed for the second copy enabling quicker and more efficient storage provisioning for similar VMs.

DAS appliances have been around for awhile now but have never been really popular. However for smaller shops, this might be just the thing to help them start down the virtualization path.  Similarly the VMware host- based data replication is a low-end capability that might help these customers virtualize, although this may be a bit more sophisticated than most SMB data centers need.

Storage performance guarantees, DRS, and automatic provisioning seem to be targeted at the higher end shops with vast storage farms to manage.  Such shops would like to automate (as much as possible) some of the performance management, provisioning and service management that they currently need to do manually to ease VMware’s storage admins workloads.

Linked clones and IO performance improvements will benefit all shops. However, IO improvements should enable bigger more mission critical applications to be virtualized.  On the other hand, linked clones will help all customers quickly and more efficiently deploy lot’s of similar VMs.


The big complaint on Twitter yesterday was on VMware’s licensing change. Apparently vSphere is licensed on a vRAM basis (the amount of virtual memory assigned to all VMs in a shop).  How this will impact customer costs is subject to debate but each vSphere processor license gets a certain amount of vRAM available to it (from 24GB to 48GB of vRAM per slot, depending on license level).

There’s been lot’s of talk about VASA and VAAI capabilities that are being rolled out by storage vendors but that will need to wait until another post.


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