FlashRecover replication on the Pure Storage FlashArray

Last year Pure Storage introduced built-in replication on the FlashArray 400 series in our Purity Operating Environment version 4.0. Our replication offers a variety of benefits–they center around two things. First it is completely free. There is no license charge for replication itself or by capacity. If you need to have is two FlashArrays and a TCP/IP network between the two of them to replicate over. No additional hardware to buy for the array or license packages required (all of our software is always free). Secondly, it is very easy to use–from a green field array to replicating volumes takes maybe five minutes–in reality probably far less than that. So I wanted to take some time to review how our replication is setup and how it works. I went over replication briefly when we released Purity 4.0, but I think it is time for a closer look.


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ESXi IO Operations Limit Parameter and IO Balance

Quick post here. I am working on updating some documentation and I wanted to add a bit more color to a section on changing the IO Operations limit for ESXi NMP Round Robin devices. The Pure Storage recommendation is to change this value to one from the default of 1,000. Therefore, ESXi will switch logical paths after each I/O instead of 1,000. There are some performance benefits to this and some evidence for improved failover time (in the case of a path failure) with this setting. I am not going to get into the veracity of these benefits right now. What I wanted to share here is that there is no doubt changing this to 1 makes a big difference to I/O balance on the array itself. Continue reading

FlashStack VMware vSphere Reference Architecture

Pure Storage announced last week our very first converged architecture offering appropriately named FlashStack. The initial release of FlashStack is built off of Cisco hardware (UCS of course) and the FlashArray. We have two reference architectures presently, one for VMware Horizon View and one for general purpose VMware vSphere environments (choose your own guest OSes). My colleague Ravi Venkat (@ravivenk) architected the View ref arch, while I focused on the general vSphere one. In this blog post I am going to overview what we did with the vSphere ref arch. For more information on either, refer to the respective reference architecture white papers at the usual place:





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Enhanced UNMAP script using with PowerCLI and RESTful API

The most common request I get for scripts here at Pure Storage is an UNMAP script using PowerCLI. I have a basic one here that does the trick–UNMAPs Pure Storage volumes in a vCenter. That being said it is pretty dumb–doesn’t tell you much about what happened other than what volumes it is reclaiming (or not reclaiming) and moves on. A few requests have come in recently for something a little more in-depth. Most notably the ability to see how much space has been reclaimed. This information cannot be gathered from the VMware side of things–it has to come from the FlashArray.

There are two options here–either use our REST APIs or use our PowerShell toolkit to get this information (which just wraps the REST calls). For this script I chose to use the REST API directly from within PowerShell. What this script does is:

  1. Connects to the vCenter and FlashArray
  2. Finds all of the datastores and counts how many are actually Pure Storage volumes (NAA comparison)
  3. Iterates through all of the datastores
  4. Skips it if it is not Pure
  5. If it is, the current data reduction ratio is reported and so the is current physical written capacity on the FlashArray.
  6. Runs UNMAP on the datastore
  7. Reports the new data reduction and physical space after UNMAP completes and how much was reclaimed.
  8. Repeats for the rest of the volumes.

The script reports all of this to the console window, but it always throws it in a log file through add-content. If you don’t want it to return the info to the console, simply delete the write-host lines. If you don’t want it to log, delete the add-content lines.

There are a few required parameters–vCenter information (IP, username, password), FlashArray info (IP, username, password), UNMAP block count and a log file location. These are hard-coded parameters, but that can easily be changed by altering it to a read-host.

You may also note that after each UNMAP the script sleeps for 60 seconds–I do this so I make sure the FlashArray has time to update its information right after the UNMAP. 60 seconds is VERY conservative–probably 10 or so is fine, so feel free to mess with that number if you don’t like waiting. I also have another sleep at the end of each datastore operation to give a quick chance to review the latest results before it starts spewing the next datastore information on the screen (note this update didn’t make it into the video demo below–it doesn’t wait after each datastore).

See the script in action below. Essentially I am deleting a bunch of VMs across 4 datastores and then running the UNMAP. You can see the space get reclaimed on the FlashArray.

The script is in Word doc form here: unmapscript

Reclaiming in-guest capacity with VMware and Pure Storage

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.

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PowerActions–The PowerCLI Plugin for the vSphere Web Client with UNMAP

The other day I stumbled upon a new VMware labs “Fling” called PowerActions. Basically it allows you to run in-context PowerShell/PowerCLI scripts right from within the vSphere Web Client. My mouth drooled at the promise of what this could deliver–and it really delivered! This is my new favorite tool by a landslide. See the announcement here from @alanrenouf http://www.virtu-al.net/2014/09/16/powercli-vsphere-web-clientannouncing-poweractions/. I’d recommend readin this first before you continue down with my post.



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