VMware vSphere: Storage - Thick & Thin Provisioning

hello I'm Brian Watchers of VMware education in this segment we're going to discuss how to use thin provisioned virtual disks as you can see illustrated in this slide it's entirely possible to have multiple virtual machines all on the same host each accessing their own virtual disks the virtual machine that you see on the left is using a traditional-style virtual disk traditionally virtual disks are thick provisioned thick provisioned virtual disks have all of their data blocks pre-allocated when you create the virtual disk so in the case of the VM on the left it's virtual disk is 20 gigabytes and we've allocated all 20 gigabytes once again because it's a thick provisioned disk the virtual machine in the middle has a thin provisioned virtual disk when you create a virtual disk you have the option to create the disk as a thin provisioned disk which we've done in this case we're creating a disk that appears to be 40 gigabytes but notice in this diagram that the actual amount of data box that we've allocated thus far is only 20 gigabytes with the thin provisioned virtual disk we delay the actual allocation of data blocks until the point in time when it's actually necessary to have those data blocks in other words we dynamically allocate data blocks on-the-fly the VM on the right also has a thin provision virtual disk you'll notice that we're creating a virtual disk in this case which appears to be 80 gigabytes but thus far we've only allocated 40 gigabytes now within provisioning one of the main benefits of thin provisioning is we're able to defer the purchase of the actual disk space that we need until a later point in time if we can defer the purchase of our storage space the same dollars that we have to spend on storage today is going to go farther and allow us to purchase more storage in the future so by deferring this purchase of the storage we're able to give the virtual machines the appearance that they have their full allocation storage space but allocate that space on the fly later on continue with this particular example you'll notice that we have a 20 gigabyte thick disc a 40 gigabyte thin disc and another 80 gigabyte thin disc for a total of 140 gigabytes now though it may seem impossible we can actually store all three of those virtual disks in the data store Illustrated on the bottom of the slide that data store only has a 100 gigabyte LUN in which there's 100 gigabyte VMFS you would think perhaps that 140 gigabytes of virtual disks wouldn't fit in that hundred gigabyte nuttin but in fact within provisioned virtual disks we can if you do a little quick arithmetic here the first disk has 20 gigabytes allocated to it the second disk though it appears to be 40 gigabytes only has 20 gigabytes so far we have 40 gigabytes total then that third virtual disk which is also thin provision is only using an additional 40 gigabytes so if you add the actual amounts of storage that we've allocated thus far 20 gigabytes plus 20 gigabytes plus 40 gigabytes that's only 80 gigabytes and 80 gigabytes of disk space will fit within a 100 gigabyte VMFS data store now that technique of creating thin provisioned virtual disks and storing thin provisioned virtual disks that appear to consume more disk space than you actually have is a technique called over-committing data stores now from that and sounds of it over committing a data store may not sound like a wise thing to do but again if we over commit data stores we can defer the purchase of the disk space to a later point in time when our dollars will purchase more if you over commit your data stores carefully using the techniques that we'll discuss here in a few moments you can safely over commit data stores but part of the burden of doing so falls on our shoulders and part of the burden of doing so correctly falls on your shoulders on our shoulders we take upon the task of making certain that we actively monitor your data store capacity we have two alarms that monitor to detect in the case of the first alarm the moment you over data store we will let you know through an alarm but additionally once a data store has been over committed or even if you aren't over committing data stores we have another alarm which will keep you posted in terms of how much storage space the a particular data store is using by default that alarm will trigger a yellow warning when you exceed 75% disk utilization and you'll trigger a red alert if you exceed 85% disk utilization so through the combination of those two alarms plus the reporting that we provide we VMware make you aware of your actual activities when it comes to thin provisioning and in particular over committing your data stores but from that point onwards it's up to you to make certain that you increase the size of the data stored if necessary to provide the disk space that we actually need so in the example of the previous slide we saw that we currently had 80 gigabytes of disk space being used in a 100 gigabyte VMFS at that point in time we have enough disk space but is the actual storage utilization level increases in that data store as we go from 80% to 85% 90 95 % you're going to want to pay attention to that second alarm to make certain that you know in advance to add the disk storage space that you need to make certain that you have the space that you need when you need it alternatively instead of adding disk space to a data store you can leverage technologies such as VMware vSphere v storage V motion to migrate virtual machines out of a data store that's filling up into a data store that still has space that way you can balance the storage needs across data stores to provide the space that we need and the following demonstration I will show you how to create thin provisioned disks in this demonstration I will show you how to create a thin provisioned virtual disk to do so I'm going to first go to VMs and templates view I'll then select the virtual machine that I want to give the virtual disk to I'll right-click the virtual machine then choose edit settings and in the Edit settings wizard we can see the hardware that this virtual machine already has notice that it currently has two virtual disks ones called virtual excuse me hard disk one the other disk is called hard disk two I'm going to add a third disk when I click Add I'm asked what type of hardware I want to add I'm going to specify I would like to add a virtual hard disk and on the following screen I'm asked whether I want to create a new virtual disk using existing virtual disks from another virtual machine or to use of raw device mapping I'm going to choose to create a brand new virtual disk and on the following screen the first thing I'm asked for is what size virtual disk I'd like to create now since I am creating a thin provisioned virtual hard disk here I have a bit of flexibility in the datastore I'm about to use there's only five gigabytes of storage space left available but notice because I'm creating a thin provisioned virtual hard disk I can create a virtual hard disk that's even larger than the amount of space that's in that datastore so to illustrate that point even though there's only five gigabytes of storage space left I'm going to choose 6 gigabytes now as i described earlier i can create a virtual disk that's thick provisioned or thin provisioned i'm going to choose a thin provisioned virtual disk in this case and i will specify specifically which datastore I want this thin provision virtual hard disk to reside in as I did before in a previous segment I will once again choose the my datastore datastore and when I click OK followed by next you'll notice that it tells us here that the disk capacity specified is greater than amount that's available in the datastore it goes on to say that disk space over-commitment can lead to filling up the virtual disk and blocking the virtual machine so it's giving us a learning right from the start that we're venturing into the territory of over committee in your data store and again if you do so wisely you can proceed safely on this screen I'm provided the opportunity to present the virtual disk in a variety of different ways I'll simply go with the defaults for now and on the following screen we have a summary that points out what we're about to do we're about to create a six gigabyte thin provisioned virtual disk in the my datastore data store if I click finish followed by ok you'll notice in the recent tasks that it tells us that we are creating a new virtual hard disk and indeed it has completed the task if we then go edit the settings for the virtual machine as you can see in the Edit settings wizard this virtual machine now has three virtual hard disks if I select the virtual hard disk that we just created artists three you can see on the right side of the interface that this virtual disk is thin provisioned the previous virtual disk that we created in an earlier segment the one called hardest to is a thick provision hard disk so in this demonstration we've seen how to create a thin provision virtual hard disk and furthermore once you start creating virtual disks of different types how to determine whether a virtual disk is thin provisioned or thick provisioned this completes this demonstration VMware Education Services offers training in over 500 training centers across the world in 60 different countries we offer both direct training and training through our view more authorized training centers we offer instructor-led training in both classroom and live online formats we offer private on sites and elearning modules available online to find out more information please see us online at the URLs listed on the screen thank you you

Channel: VMware

Views: 138,659

Keywords: virtual storage provisioning, thick and thin provisioning, vsphere getting started, vsphere video training series, vmware install help, free vmwarer training, vmware training video

Id: -8FoEl6CeYo

Length: 11min 19sec (679 seconds)

Published: Fri Mar 30 2012