{"id":12112,"date":"2012-03-03T18:58:51","date_gmt":"2012-03-03T18:58:51","guid":{"rendered":"https:\/\/aidanfinn.com\/?p=12112"},"modified":"2012-03-03T18:58:51","modified_gmt":"2012-03-03T18:58:51","slug":"the-virtualisation-smackdown-hyper-v-vhd-scales-out-to-64-tb-yes-i-said-64-terabytes","status":"publish","type":"post","link":"https:\/\/aidanfinn.com\/?p=12112","title":{"rendered":"The Virtualisation Smackdown \u2013 Hyper-V VHDX Scales Out to 64 TB \u2013 Yes, I said 64 Terabytes!"},"content":{"rendered":"

I was gobsmacked when I learned this week that the new Windows 8\/Windows Server 2012 (WS2012) format for virtual disks, VHDX, would have a maximum size of 64 TB<\/a>.\u00a0 64 TB!\u00a0 Damn, I was impressed with the Build announcement that it would go out to 16 TB.\u00a0 Even then, it was dwarfing the paltry 2040 GB that vSphere 5.0 VMDK can do.\u00a0 Wow, Hyper-V has vSphere smacked down on storage scalability; isn\u2019t that a shocker!?!?!<\/p>\n

Back to the serious side of things \u2026 what does this mean?\u00a0 One of the big reasons that people have implemented virtualisation (28.19% \u2013 Great Big Hyper-V Survey of 2011<\/a>) was flexibility.\u00a0 What makes that possible is that virtual machines are normally just files, unbound to their hardware they reside on unlike legacy hardware OS installations and data storage.\u00a0 A limiting factor on that has been the scalability of virtual disks.\u00a0 Both VHD (pre-Windows 8 Hyper-V) and VMDK (all current versions of vSphere) are limited to 2040 GB.\u00a0 The alternative is Raw Device Mapping (vSphere) or Passthrough disk (Hyper-V).<\/p>\n

I hate <\/em>this type of storage.\u00a0 It\u2019s bound to disk because it\u2019s just a raw LUN presented to a VM and therefore it\u2019s a hardware boundary that limits mobility, flexibility, and precludes other things that we can do such as Hyper-V Replica, snapshots, VSS backups of running VMs, etc.\u00a0 Way too often I see people using Passthrough for \u201cperformance\u201d reasons (usually with no assessment done and based on pure guesswork) without realising that even VHD has great performance (and I cannot wait for VHDX performance results to be published publicly).\u00a0 The only real reason to use Passthrough disk in my opinion has been to scale a VM\u2019s LUN beyond 2040 GB.<\/p>\n

That changes with Windows Server 2012 Hyper-V.\u00a0 I am thinking that Passthrough disk will become one of those things that is theoretical to 99.999999% of us.\u00a0 It\u2019ll be that exam question that no one can answer because they never do it.\u00a0 Think about it: a 64 TB virtual disk that performs near as good as the physical disk it sits on.\u00a0 Wow!<\/p>\n

Question: So which virtualisation platform isn\u2019t scalable or enterprise ready? *sniggers* I cannot wait to see the excuses that the competition come up with next.<\/p>\n

There are other benefits<\/a> to the VHDX format:<\/p>\n