Deep Dive into VMware Snapshot | Virtual Machine Snapshot -Deep Dive

everyone welcome to vmware in our youtube channel if this is the first time you're watching video in this channel please do subscribe to the channel to support us and also to get the latest updates about them many videos which i am posting about vmware virtualization and other tech modulation technologies so in this video today i'm going to talk about what is virtual machine snapshot and what are the files which makes up the snapshot so what is the concept of VMware snapshots for how does you know like virtual machine handles the snapshot and what are all the important discs changes which happened at the virtual machine so I'm going to talk about all these things with the whiteboard session and I will move towards a practical example I will show lively when I create a snapshot so what will be change it to the virtual machine folder and what all of the files will be changed and how the virtual machine you know writing and behavior changes when me working with a snapshot let's get started so basically VMware snapshot is which helps us to preserve the state and date of virtual machine at a specific point of time so snapshot includes rate or data including a disk memory and other devices such as network adapter on whatever the changes we made it to the disk okay and other thing is snapshot are extremely useful which simplifies the virtual machine operating system and maintenance tasks so it helps us to preserve the current state of virtual machine so it allow us to revert to the state of virtual machine prior to taking the snapshot okay so here is an example I have a watchman called VM one so virtual machine is nothing but a group of files so when we create a virtual machine there are a lot of files will be getting created to the directory for virtual machine is stored some of them are like vm x which is configuration file and there will be other things like VMDK file and flat dot VMDK files right so VMDK is nothing but virtual machine descriptor file the disk descriptor file so it will be having the reference to which is the actual disk right so what about the flat dot VMDK the flooded VMDK is the actual disc where your virtual machine right will be saved here so if you if you see if you edit the virtual machine from one vSphere client you see VMDK file but if you browse towards the directory of your virtual machine you will come to know the flat that VMDK which is having the same size as your virtual machine disk size imagine this is a Windows machine so Microsoft releases patches every month so imagine I want to install on the last month patches which is May 20 20 pages on my Windows operating system to preserve the state ok so in this case I want to preserve the state of virtual machine before I install these patches ok so I mean like if something has happened or some it crashed my operating system I should have something to snapshot to revert back to the old state so I'm creating a snapshot here and the snapshot I'm naming like a snapshot before patching so I created a snapshot so it halves to snapshot helps to preserve the state of virtual machines so once I create the snapshot so what will happen is so inside the virtual machine directory you can notice VM 1 - 0 0 0 0 5 times 0 1 dot VMDK will get created which is nothing but the descriptor file for your snapshot disk which is nothing but a delta disk so and also it will create a delta disk called vm 1 - 0 0 0 0 1 - Delta dot VMDK will get created here ok so basically your virtual machine will be pointed to the VMDK which is created the snapshot VMDK vm 1 - 0 0 0 dot descriptor file VMDK file and all your virtual machine know so your virtue may should be mapped with VMDK and VMDK will have a pointer to the Delta s so all the rights which is coming to your virtual machine will be written to the Delta so it means so whatever changes you are making it after you take the snapshot will be only written to the Delta disk so your world flat dot VMDK which is the parent disk will only have a read-only so if you need the virtual machine need some data which needs to be read from disk it will happen but all the writes will only happen to that Delta disk ok so by this what it happens is snapshot will preserve the state of the disk so if I want to you know like so whatever rights which is coming will only come to the Delta right so if I want to revert back to the world state so I can just select the snapshot and revert back so it will go back to the state before I install the patching ok which is a Microsoft patches so as I said the read will hope only the flood that VMDK parent disk will only have a read imagine you want to take another snapshot ok so after the MS insulation like patches I'm going to upgrade some of the software in my Windows version so I am taking another snapshot let's name this as snapshot before upgrade ok so I take another snapshot so what will happen to the existing file right so it will create on another VMDK on another Delta dot VMDK inside the same virtual machine directory so it will be named like vm 1 knife and 0 0 0 0 2 dot VMDK and same like vm 1 - 0 0 0 0 5 times 0 2 - Delta dot VMDK will get created for the second snapshot so again your virtual machine rights will be redirected to the new Delta disk and the flag dot VMDK and first Delta disk will become a read-only so all the rights will be going the virtual machine will be mapped with VM the 0 0 0 2 VMDK file ok so if we want to go back to the world state like after after the patching we can also revert using the snapshot which is we have taken snapshot before patching or you want to go back to the old state before we install a most batching we can revert back to the first snapshot which is snapshot before patching okay so it gives the option us to roll back if something to the previous state which we have taken so this is one of the example I taken a screen shot so you can see the VM name is set at that one so it will have a VMDK usually and it will have a red dot one - flat dot VMDK which is the actual disk you can see the size which is equal into your this size so it creates an Delta disk called - Delta dot VMDK and snapshot like VMDK zero zero zero one dot VMDK it got created there will be something called vm SD which is a snapshot database file so basically it preserves the how many snapshot which we have it will be reporting to your snapshot from your vCenter server GUI ok so we understand how does write work so let's talk about some of the concepts log when we create a snapshot the state of this will be preserved rights to the VMDK is not allowed so system creates an additional VMDK file called delta disk for each VMDK disk in the datastore run allows writing any changes to the Delta disk so Delta disk represents a difference between a current state of virtual disk and state that exist at the time of pria snapshot as we discussed right so Delta disk whatever the changes after the snapshot will only return to the Delta disk so if multiple snapshots are taken so Delta disk will be created for each of the VM discs for every snapshot it represents the difference between every snapshot ok for each of the snapshot so new Delta s will be created what if your VM first version so after VSPs 6.5 that delta there will be no more Delta disk they renamed it as VM one eyghon 0 0 0 1 - SE sparse that disk so Delta disk is a world of format if you have a vSphere which is older than V spear 6.5 you will see the Delta file or if your VM first version is 6.0 or later you will see only the SE sparse which is nothing but the Delta s the SE sparse will provide a more functional to further reclaim the space reclamation okay so once we delete the snapshot the space will be quickly reclaimed in Macy's past this so that's why they introduced the icy spots disk in vSphere after VSP a 6.5 if your VM first version is 6r later ok so we talked about the concept of Lee let's take let's connect to the vCenter server and we'll see the real-time example how does it work so I have a Windows machine called win - vm 0 - so this is running on MDS 6 a 0 - as of now I don't have any snapshots here ok I don't have any snapshot here let me connect to the ESXi host to understand what is the virtual machines file which exists before we create the snapshot so I kind of I logged into the ESXi host let CD into the CD VM first volumes and go to the data store where this particular machine is stored so this is stored in I scuzzy data store let's see D - I scuzzy data store CD I scuzzy their store f-101 put a LS it lists all the virtual machine which is running inside the datastore so this will be CD win - VM - 0 - ok yeah let's LS so let's let's put a LS ok let's understand so this virtual machine will have is having one VMDK ok so I have a VMDK file which is there yeah you can see the size was like 663 KB's or something bytes so we have a flat dot VMDK which is 90 gig which is equal to the size of my VMDK file so let's go back to my virtual machine expand the hard disk will confirm it so expand the hardest you can see that the your hard disk is map to V knife and VM 0 2 dot V MDK which is a descriptor file so flood that VMDK is created for that particular disk ok so apart from that you may see VMs D which is snapshot database file source of noid don't have any snapshot so once we create a snapshot it'll have information so if you read the VMDK so basically VMDK file will have the what is the format what kind of version it is so it also have the pointer to the flat dot VMDK file so which where the actual my virtual machine disk will be going there what is a disk UID all the information will be written in the VMDK file ok so this is a VMDK file which is mapped to the virtual machine ok so we have a flat VMDK which is there so apart from that there is not notice no files related to that file then as I told VMs D is nothing but a watch machine snapshot data file so basically it provides the information about how many snapshots exist for the virtual machine and it will be displayed in your vCenter server vSphere client ok so let me take a snapshot so I'm going to take a snapshot right click take a snapshot so I'm going I'm not going to select the virtual machine memory snapshot so memory snapshot will preserve the memory state of virtual machine so it exactly revert to the state where it is wash machine was running it means like if it is powered on it will power down it will revert it ok so I have taken a snapshot so let me LS it again so here is the changes right now I see there is a VMDK which is vin knife and vm 0 2 - 0 0 0 1 dot snapshot VMDK which is descriptor file got created VMDK and i have a flat dot VMDK since this is vm first version 6 so instead of delta it created wind - 0 - 0 0 0 1 knife an AC spot VMDK so basically all the writes will go to the AC spot vm disk so as per so when we take a snapshot your virtual machine will be point at your virtual machine writes will go to the SE space disk so s is past disk so the snapshot VMDK will have to pointer to this virtual machine so it will automatically point to the snapshot disk so earlier it was pointed to V knife and VM 0 to dot VM DK now it is pointer to the snapshot this so whatever the right switch is coming to the verge machine will be written to this VM zero zero zero one dot VMDK basically if you read the VMDK it will show what is a parent disc it will show the parent disc details so it shows right parent disc a file name is Vinh - vm phase zero - actual VMDK is a parent disc it will also show pointer to the which is the actual data disc we can see even knife and vm - 0 0 0 s is positive so whatever the right switch is coming to the virtual machine will be written here so it preserves the existing state before we make changes to this particular operating system so if you want to roll back to the previous state we were able to do it what if we create on another snapshot right let's take another snapshot and let's name this as snapshot before upgrade as we discussed in the previous example so I'm not including the memory snapshot let's exclude this click on ok so snapshot has been created let's go back to the ESXi so before that will validate the snapshot okay I have a - snapshot which is snapshot before Windows patching and latest only snapshot before upgrade so let's put LS ok so now I should have a VM - VM 0 to iPhone 0 0 0 2 dot VMDK and 0 0 0 2 dot a c-spot start disk so this will be created for my second snapshot so whatever the writes now coming to the virtual machine will be pointed to this one will be directly written to this the second snapshot disk so it preserves the state between the first snapshot and second snapshot and the first snapshot prefers the preserves the state between the parent disk and the new snapshot so if you want to go back to without patching I can select it and revert back so it will go to the previous state before we perform the software upgrade so if you want to click on Windows patching and revert it it will go to the parent state where we before before state before we on the back okay we understand when we create a snapshot so Delta is created and virtual machine is pointed to the Delta disk and the read and write has been given to the Delta disk and only the parent VMDK will be read only so we understand how does the internal things works so let's take some of the snapshot maybe we will take two snapshots one with a memory and one without a memory snapshot without memory snapshot then we will revert the snapshot to understand how does the operating system behaves when we revert the snapshot okay so basically I will take one snapshot with memory and one without on memory will revert the snapshot and we'll understand from the Windows operating system or any operating system perspective so what does it changes how does the snapshot preserves the state of virtual machines when it when we try to help okay so this is a virtual machine called wind vm 0 - I just copied the two software installer so maybe which is VMware OVF tool which helps us to convert VMware various formats of virtual machine go via to OVF virtual machine - OVF all these things so I'm going to install the worthy of tool on this particular machine ok so before I get installed so I am going to take a snapshot on this virtual machine called wind vm 0 1 so I will specify the snapshot name called before consider this is anything you get installed right for example you are installing the patches as per our earlier example ok so I will say snapshot before software install ok so I have selected the option snapshot the virtual machine memory so basically with this snapshot the memory state will also be captured and in the memory file so when we revert the snapshot it just reverts to the exact same state what is there in the virtual machine memory ok so I have selected the option snapshot virtual machine memory so basically when we take a snapshot with virtual machine memory so it may take the snapshot the time to take the snapshot may be little longer than the normal snapshot okay I click on okay so I'll be moving forward to avoid the video length okay so maybe I will show what is the completion time how long it took Stu okay so here it started basically if you have taken without memory snapshot by this time the snapshot would have created but it takes a little longer time because it have to capture the virtual machine memory state as well okay so it's completed so let's see the completion time so it started at around 96 and completed around nine eight so it took around two minutes to take the snapshot because it have to capture the memory state of that particular virtual machine let's validate whether the snapshot is created yes so the snapshot is their snapshot before software install is there so in the right side we can see the snapshot virtual machine memory yes the size of the virtual machine is snapshot is around a ten point nine 4gb and it shows a creator time a name of the snapshot okay so I created the snapshot so let me go back to the Windows operating system and we install this VMware OVF told okay so I posted on a dedicated video about how to use a VMware OVF tool to convert OVA to OVF images or if you want to deploy convert from whoa VF to OVA or you want to export a virtual machine as a movie a template all these things I have talked about that in the video I will just put it in the iCard you can get the details about that particular video okay so it takes the insulation so it started the insulation yes like any Windows installer just click on next next to install this so basically it updates operating system files and it deploys the software related files and created a folders and this after get installed these are all the changes we are making at the Windows operating system after we create the snapshot okay so whatever the new right switch over this after we are getting installed new rights of the snapshot will be pointed to our Delta disk so all the rights will be returned to the Delta disk once we created the snapshot okay so the insulation is come okay we haven't solved click on finish install the another software as well which is something called free of TPD which helps us to create on ftp on your window server I hope this insulation will be yes the insulator ok it's gonna finish let's refresh it yes so I have a to software which could install VMware ODF tool and we are free FTP D ok so this both the software's got installed after we take a snapshot so whatever the changes which was happened on this particular disk will be written to the Delta disk so let's revert the snapshot remember guys this is a snapshot with memory ok we have taken the memory snapshot so I have selected the snapshot to revert to that particular snapshot so I need to select so this is as I said this is a snapshot which memory so let's see how does the snap chart reversal work with memory snapshot so we have to select this snapshot click on River to so it will revert your virtual machine to the previous state before we take the snapshot okay so convert state of virtual machine will be lost until it saved a snapshot River to the snapshot yes click on OK click done let's open up ok the console may be disconnected let me open up the console again as I said when we revert the snapshot with memory snapshot option so whatever running in the virtual machine memory before we take the snapshot it reverts to the same state it means it also preserves the power state of virtual machine ok so here is the I reverted the snapshot but I don't see the two softest which we have installed which is VMware OVF tool and FTP which is not there but the virtual machine is still powered on straight okay so it just reverts the virtual machine to the same state including the memory state when we take the memory snapshot so as we understand the memory snapshot may take a little longer time to create and also the size it grows will be higher because it have to capture the the memory contents of that virtual machine okay so now we understand the memory snapshot how to revert the memory snapshot and how does the operating system behaves when we revert the snapshot which is taken with the memory okay so let's go back and we'll delete this snapshot first click on OK it will get deleted yes it's let's take on another snapshot without memory and we will understand how does the reverse snapshot works ok so it was same state as of now it's not installed with anything so before installing the software I am taking the snapshot here so this time let me specify the same name I think snapshot before so this time we will take a snapshot without a memory state ok so we have to uncheck the snapshot virtual machine memory because by default it is enabled ok just uncheck the option snapshot virtual machine memory so it will not capture the memory state of virtual machine it will only preserve the disk and other configuration like virtual machine configuration and vmx and other configuration but it will not capture the operating system whatever there in the memory contents okay so the snapshot is very quick it completed within few seconds ok within few seconds it it got completed because this is not the snapshot with memory so it's a normal snapshot so let's install the software okay thus after installation has been completed let's refresh it yes the VMware OVF tool is installed so you we have taken a snapshot before we install the OVF tool which is without the memory let's revert the snapshot okay we can also select a river to let a snapshot to revert to the latest snapshot which we have taken it select the snapshot click on revert which is not memory snapshot okay click on OK click on done ok so now we see the difference your virtual machine is powered off ok because this is not the memory state it will not capture the you know like your operating system state basically it will only preserve the disk state ok so whatever changes it makes to the disk will be reverted back so we have to go ahead and manually power on the virtual machine so it preserves the same state as before the so as I said it is powered off I just powered on ok so in the in when we take the snapshot with memory for example you open up a 10 different application like you are working on some of the excel sheet and your you're writing some notes on the notepad something like that so you if you take a memory snapshot and you feel reverted right so it preserves the whatever there in the operating system memory as well so when we revert the snapshot the whatever the files which you are working on it will be still open it preserves the entire state but it's not the case with the snapshot without memory so most of the cases the snapshot without memory is perfectly fine because we need to roll back to the changes before whatever the changes we make on the operating system right we don't care about what is there we really don't need to preserve the same status in the memory because so we take a snapshot before making any of the changes only it's not to preserve the state actually ok so now the snapshot is reverted so I don't have the soft snapshot the software which I have installed it so it go it went back to the same state before we take a snapshot but this virtual machine was powered on I have to power on right so I hope this article help you to understand a detailed information about what is a VM a snapshot what are the files involved when we take a snapshot how does the snapshot behaves and what are the Delta disk how does the create a snapshot with memory and without memory how can we revert the snapshot and how does the operating system behaves when we revert the snapshot with different snapshot options such as with and without memory I hope you got better information about VMware snapshot I hope this is infirmity for you please please do subscribe to the channel to support us thank you so much bye-bye

Channel: VMware Arena

Views: 9,764

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Keywords: vmware snapshot, vmware snapshot explained, vmware snapshot consolidate, vmware snapshot restore, vmware snapshot background process, vmware snapshot step by step, vmware snapshot delete, vmware snapshot best practices, vmware snapshot deep dive, vmware snapshot delete all, vmware snapshots backup, vmware snapshot guide, vmware snapshot process, vmware snapshot without memory, how vmware snapshot works, virtual machine snapshot vmware, vm snapshot explained

Id: TbRLu8koF1w

Length: 27min 46sec (1666 seconds)

Published: Mon Jun 22 2020