This is the second part of this post. In the first post, I explained the fix and how it affected Windows. In this post, we will overview how the change affects Linux-based virtual machines. See the original post here:
In-Guest UNMAP Fix in ESXi 6.5 Part I: Windows
I posted about In-Guest UNMAP with Linux VMs in this post:
What’s new in ESXi 6.5 Storage Part I: UNMAP
One thing you can note is that automatic UNMAP works quite well, but manual UNMAP, like fstrim did not. So let’s revisit fstrim now that this patch is out. Continue reading In-Guest UNMAP Fix in ESXi 6.5 Part II: Linux
Reclaiming “dirty” or “dead” space is a topic that goes by my desk quite often these days–since the FlashArray is a data reduction array it is especially important that space is not wasted on the array–throws off the economics etc. Therefore UNMAP is an important VAAI feature to leverage in any AFA environment. Supporting UNMAP is definitely table stakes for AFAs.
Note–I am doing to use the terms “dead”, “dirty” and “stranded” to define space that needs to be reclaimed interchangeably. So anyways…
Unfortunately UNMAP in its current form does not satisfy all of the reclamation use cases. UNMAP will only reclaim space on any array when capacity is cleared from the VMFS volume–so when a VM (or virtual disk) is deleted or migrated elsewhere. It does not have the ability to reclaim space when data is “deleted” inside a virtual machine by the guest OS when using virtual disks. VMware does not know this capacity has been cleared and neither can the array. So until this virtual disk is deleted or moved the capacity cannot be reclaimed with UNMAP. So to be clear, UNMAP with vmkfstools (in ESXi 5.0/5.1) or esxcli (in ESXi 5.5) does not allow you to reclaim space that remains stranded inside of virtual disks.
Continue reading Reclaiming in-guest capacity with VMware and Pure Storage
One of the main things I have been doing in my first few weeks at Pure Storage (which has been nothing but awesome so far by the way) is going through all of our VMware best practices and integration points. Testing them, seeing how they work or can they be improved etc. The latest thing I looked into was Dead Space Reclamation (which from here on out I will just refer to as UNMAP) with the Pure Storage FlashArray and specifically ESXi 5.5. This is a pretty straight forward process but I did find something interesting that is worth noting.
Continue reading VMware Dead Space Reclamation (UNMAP) and Pure Storage