Recent Posts

VMFS Heap Considerations

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[Updated 29-April-2013] By default, prior to 5.0p5 & 5.1U1, an ESXi host has 80MB of VMFS heap at its disposal. This is defined in the advanced setting VMFS3.MaxHeapSizeMB. The main consumer of VMFS heap are the pointer blocks which are used to address file blocks in very large files/VMDKs on a VMFS filesystem. Therefore, the Read more...

Some useful vmkfstools 'hidden' options

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I was recently playing around with vmkfstools, checking out a few things for one of our storage partners. I noticed that I was using some undocumented options to look at a few things, and thought I would share them with you here.   1. Display hosts which are actively using a volume ~ # vmkfstools Read more...

Advanced VMkernel Settings for Disk Storage

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As regular readers will know by now, many of these blog posts are a result of internal discussions held between myself and other VMware folks (or indeed storage partners). This one is no different. I was recently involved in a discussion about how VMs did sequential I/O, which led me to point out a number Read more...

VAAI Offload Failures & the role of the VMKernel Data Mover

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Before VMware introduced VAAI (vSphere Storage APIs for Array Integration), migrations of Virtual Machines (and their associated disks) between datastores was done by the VMkernel Data Mover (DM). The Data Mover aims to have a continuous queue of outstanding IO requests to achieve maximum throughput. Incoming I/O requests to the Data Mover are divided up Read more...

Path failure and related SATP/PSP behaviour

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Posted by Cormac HoganTechnical Marketing Architect (Storage) This question came up in a recent conversation about what happens in the Pluggable Storage Architecture (PSA) when there is a path failure. It basically describes the roles played by both the Storage Array Type Plugin (SATP) and the Path Selection Policy (PSP) when a path fails, resulting Read more...

VMworld 2012 – Some Interesting Storage Sessions

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You'll probably know by now that the VMworld 2012 content catalog has gone live. I've had a look through the catalog to see which storage sessions caught my eye. The majority of these are technical, but some of them are designed you give you some sneak peaks at VMware's storage vision. First a shameless plug. Read more...

Low Level VAAI Behaviour

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We’re getting a lot of queries lately around how exactly VAAI behaves at the lower level. One assumes more and more VMware customers are seeing the benefit of offloading certain storage intensive tasks to the array. Recently the questions I have been getting are even more in-depth. I’ve been back over my VAAI notes gathered Read more...

Nutanix announces more vSphere integration features

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Posted by Cormac HoganTechnical Marketing Architect (Storage) For those of you who don't know about Nutanix, these are the folks who won a gold award for desktop virtualization at VMworld 2011 last year. Their complete cluster product is both a hardware and software solution that delivers compute and storage to run virtual machines and store Read more...