Recent Posts

VAAI Thin Provisioning Block Reclaim/UNMAP In Action

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Posted by Cormac HoganTechnical Marketing Architect (Storage) I have done a number of blog posts in the recent past related to our newest VAAI primitive UNMAP. For those who do not know, VAAI UNMAP was introduced in vSphere 5.0 to allow the ESXi host to inform the storage array that files or VMs had be Read more...

Does VMware Support Shared/Switched SAS?

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An interesting observation was made on a previous blog posting of mine which compared different storage protocols. The commenter asked why I didn't include Shared SAS in the comparison (SAS is Serial-Attached SCSI). I personally have not seen a lot of shared SAS configurations, so I decided to have a look at what is on Read more...

Exiting VSA Maintenance Mode using WSCLI

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I recently learnt about a built-in safety mechanism on the vSphere Storage Appliance when too many reboots of the host takes place. A VSA server will enter maintenance mode silently if it is rebooted 3 times in 15 minutes. If a member is in maintenance mode, then it does not join the cluster. If the Read more...

VM Storage Profile behaviour when VASA Provider fails

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I recently had a question around what happens to the compliance state of Virtual Machines that are using VM Storage Profiles which are built on top of storage capabilities surfaced by a VASA provider, and that VASA provider has an outage and is no longer reachable. The current behavior is that once the provider becomes Read more...

Debunking Storage I/O Control Myths

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I had the pleasure of presenting to a number of our customers and storage partners last week. Both sessions were very interesting as it gave VMware technical marketing a chance to elicit some good feedback about what's working well and what's not working well from a vSphere perspective. One of the things which surprised me Read more...

VASA, Profile Driven Storage & RDMs – Heads Up.

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I had a discussion earlier this week with Cody Hosterman from EMC. Cody was working on VASA & Profile Driven Storage, and spotted some anomalies in the way the feature works with RDMs, VMware's Raw Device Mappings. RDMs, as the name implies, using a mapping file to maintain details about a physical LUN that is Read more...

Ye olde Controller, Target, Device (ctd) Numbering

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I was having a discussion today about something that had not come up in a long, long time. It was about how controller numbers, target numbers and device numbers are assigned on an ESXi host. The scenario is a Microsoft Exchange implementation where the requirements are to have separate LUN for each DB & Log. Read more...

VAAI Thin Provisioning Block Reclaim/UNMAP is back in 5.0U1

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When vSphere 5.0 launched last year, I did a post on the new VAAI (VMware Storage APIs for Array Integration) primitives. One of the cool new features was the the ability to reclaim stranded space on Thin Provisioned datastores, something we could not do previously, which meant large amounts of stranded space could be left Read more...