Category: VAAI

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Issue with Manual VMFS-6 UNMAP and Block Count

So vSphere 6.5 introduced VMFS-6 which came with the highly-desired automatic UNMAP. Yay! But some users still might need to run manual UNMAP on it for some reason. Immediate reasons that come to mind are:

  • They disabled automatic UNMAP on the VMFS for some reason
  • They need to get space back quickly and don’t have time to wait

When you run manual UNMAP one of the options you can specify is the block count. The UNMAP process since 5.5 iterates through the VMFS, by issuing reclaim to a small part of the VMFS, one at a time, until UNMAP has been issued to all of the free space. The block count dictates how big that segment is. By default ESXi will use 200 blocks (which is 200 MB). Continue reading “Issue with Manual VMFS-6 UNMAP and Block Count”

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Detecting what FlashArray VMFS Volumes Have Dead Space

Another UNMAP post, are you shocked? A common question that came up was what volumes have dead space? What datastores should I run UNMAP on?

My usual response was, well it is hard to say. Dead space is introduced when you move a VM or you delete one. The array will not release the space until you either delete the physical volume, overwrite it, or issue UNMAP. Until vSphere 6.5, UNMAP for VMFS was not automatic. You had to run a CLI command to do it. So that leads back to the question, well I have 100 datastores, which ones should I run it on?

So to find out, you need to know two things:

  1. How much space the file system reports as currently being used.
  2. How much space the array is physically storing for the volume hosting that file system.

Continue reading “Detecting what FlashArray VMFS Volumes Have Dead Space”

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Allocation Unit Size and Automatic Windows In-Guest UNMAP on VMware

I posted shortly after ESXi 6.0 came out a while back explaining how to do in-guest UNMAP with Windows. See the original post here:

Direct Guest OS UNMAP in vSphere 6.0

The high-level workflow if you don’t want to read the post is:

  1. You delete a file in Windows
  2. Run Disk Optimizer to reclaim the space
  3. Windows issues UNMAP to the filesystem
  4. ESXi shrinks the virtual disk
  5. If EnableBlockDelete is enabled on the ESXi hosts, ESXi will issue UNMAP to reclaim the space on the array

This had a few requirements:

  • ESXi 6.0+
  • VM hardware version 11+
  • Thin virtual disk
  • CBT cannot be enabled (though this restriction is removed in ESXi 6.5 see this post)

Continue reading “Allocation Unit Size and Automatic Windows In-Guest UNMAP on VMware”

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What’s new in ESXi 6.5 Storage Part IV: In-Guest UNMAP CBT Support

This is the fourth in my series of what’s new in ESXi 6.5 storage. Here are the previous posts:

What’s new in ESXi 6.5 Storage Part I: UNMAP

What’s new in ESXi 6.5 Storage Part II: Resignaturing

What’s new in ESXi 6.5 Storage Part III: Thin hot extend

Here is another post for vSphere 6.5 UNMAP! So many improvements and this is a big one for many users. Certainly makes me happy. Previously, in vSphere 6.0.x, when in-guest space reclamation was introduced, the enabling of change block tracking for a given virtual disk blocked the guest OS from being able to issue UNMAP to that disk and therefore prevented it from leveraging the goodness it provides. Rumor has it that this undesirable behavior continued in vSphere 6.5…

leecorso

Continue reading “What’s new in ESXi 6.5 Storage Part IV: In-Guest UNMAP CBT Support”

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VMFS UNMAP switches block count

A recent question I got about my UNMAP PowerCLI script was it says it was using a certain block count but when I looked at the log it was using 200. Why?

Well I blogged before about why a given UNMAP process might revert to the default block count of 200 here. Essentially, if you indicate a block count larger than 1% of the free space of the VMFS ESXi will revert it to 200. Or if the VMFS is more than 75% full it will always override the block count back down to 200. Continue reading “VMFS UNMAP switches block count”

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Running UNMAP with vRealize Orchestrator

Let me start out with saying I’m embarrassed I have only been using vRO for 8 months or so. It is AWESOME.

The FlashArray Workflow Package for vRealize Orchestrator has been updated to include two new objects:

  1. Auto-expand datastore policy template
  2. Workflow to run UNMAP on a datastore

The creation of the first part is explained in this post. But if you are using the FlashArray it is all built into the package, so you have to do very little work. I’ll explain in a bit.

The UNMAP workflow is generic–it can be used with any VMFS datastore that supports UNMAP. So it is included in the workflow package and it is also standalone for those of you who don’t have a FlashArray. You can get the standalone here:

https://github.com/codyhosterman/orchestrator/blob/master/vmfsunmap.workflow

Continue reading “Running UNMAP with vRealize Orchestrator”

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VAAI XCOPY not being used with Powered-On Windows VM

This is an issue I discovered along with my good friend and former colleague Drew Tonnesen a few years back which has cropped up a few times in recent days. I noticed there wasn’t really any information about it online, so made sense to put a quick post together.

In short, Windows 2012 R2 virtual machine clone or Storage vMotion operations complete much slower when powered-on as compared to when power-off. The common explanation is that VAAI XCOPY does not work when the VM is powered-on. This is not exactly true. Let me explain. Continue reading “VAAI XCOPY not being used with Powered-On Windows VM”

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ZeroedThick or EagerZeroedThick? That is the question.

Having a best practices conversation the other day with a customer and the usual topic came up about any recommendations when it comes to virtual disk type. We had the usual conversation thin or thick, the ins and outs of those two. In the end it doesn’t matter too much, especially with some recent improvements in ESXi 6.0. The further question came up, well what about between zeroedthick and eagerzeroedthick? My initial reaction was that it doesn’t matter for the most part. But we had just had a conversation about Space Reclamation (UNMAP) and I realized, actually, I did have a big preference and it was EZT. Let me explain why.

Continue reading “ZeroedThick or EagerZeroedThick? That is the question.”