Vm stun during snapshot. 5 TB) will get about halfway and lock up.

Vm stun during snapshot In fact, after i take a snapshot the time offset become about 1 minutes. ) It's a known issue with VMware that it performs what is called a "stun" during certain operations, such as vmotion, and snapshot create/delete. This helps in reducing lengthy backup windows and application timeouts, ensuring more efficient and reliable backup operations. You can reproduce it easily without Veeam server activity, just create a snapshot, give it a bit time to grow and then start the commit operation. 0U1. Alsowhen I perform manual snapshots and removals, I do not Host-based backup of VMware vSphere VMs. 41 11. The original virtual disk is in read-only mode. All I ever use quiescing for is when snapshotting a running sql server for Stuns will also occur when a VMware snapshot is deleted. 0 Recommend. I have seen that we Snapshot stun times improved a lot with 7. To determine this stun time, check the vmware. Hi . Internal memory is not included in the snapshot. tractng. Hello, Currently, the snapshot is being deleted (60%), so the question is can I restart the VM machine? when you are removing (consolidating) a snapshot you normally can restart the vm. It task status window in Vmware web client i see "Creating VM Snapshot 0%" and it hangs. Using ESXi5. Open a support ticket with VMware support to investigate further. For databases with high transactional throughput, these pauses can significantly impact performance 3. I'm not able to access VM at that time, not able no restart it, not able even to reset. For VMs stored on an NFSv3 Datastore: The primary benefit of using storage snapshots in Veeam backup and replication is to avoid potential VM stun issues during snapshot commits. This short freeze is often referred to as stunning the VM. The VM shows as being online in vCentre but it doesn’t show as having an IP address or that VMware tools is installed. com 11. During backup VM freezes for more than 30 seconds. When the consolidation occurs a new file is created where all the changes and original disk are written to. #1 Global Leader in Data Resilience . If while performing the test above the same connectivity issue as during the vProxy backup job are observed, then issue likely exists within the VMware environment. VMware recently patched an issue in 6. VMDK but if the system needs to refers to a file before the snapshot it will refers to VM_Name. 0 coins. The stun/freeze happens to accommodate the changes to be written back to the base disk from the Delta disks. During a memory state snapshot capture, the VM is stunned to serialize the VM’s state to disk and close the running disk. The worst are VMs on several datastores with several branches of Now, here is an important distinction, which most people in this thread are getting incorrect. A QUIESCENT SNAPSHOT DOES NOT STUN THE OPERATING SYSTEM!! Keep in mind that snapping memory can stun a VM for a few seconds depending on how much memory there is. Posted Apr 01, 2015 10:29 PM. that usually takes 1 ping to update. 5 TB) will get about halfway and lock up. Edit: Since not all applications respond to a request to quiesce their disk usage, there are only two totally safe ways to make a snapshot: take a memory snapshot so that the VM memory and disk comes back exactly to the point where it was 'stunned', mid disk write and all. Ah, the ole snapshot merge and stun nugget! We have hundreds of VMs a) Create quiesced snapshot (which what Veeam Backup does, but this is not a default option in VMware Infrastructure Client). Snapshot function should be working properly at this stage. When this happens, system time in VM also stops and resets to current time after the freeze. VMware vSphere uses the “rolling snapshot” for older versions and the same method as storage vMotion uses starting from vSphere 6. create new delta disks, etc. This quiescence prevents the data corruption problems that can occur with unassisted hypervisor snapshots. So, as a first step of investigation I would recommend reproducing this situation in order to understand by whom this issue should be addressed (VMware, Veeam). The snapshot being created is non-quiesced and doesn't include virtual machine The VM stun time to complete Snapshot creation operation directly correlates with number of VMDKs associated to a Virtual Machine. I finally fixed it last night by adding the line below to the vm's vmx file. I notice during the snapshot removal 95% that the SQL VM would freeze - this is very very very bad. This issue is exasperated on large datastores (32TB or greater). During this close/delta create/attach period, the virtual machine is stunned. Veritas - now part of Cohesity. In case of pending change block tracking initialization this phase of snapshot creation will result in longer stun time. I have logged a call with VMWare and they have looked into it and determined that everything is working as designed (ie yes there will be a pause right at the start of the snapshot it’s the running memory When using vSphre 6. VM snapshot removal stun is expected behavior of any Virtual Machine in VMware since VMware has to shift the active writes to disk from the snapshot file back to the base disks. [2014-02-02 21:49:38. When a backup is performed using HotAdd mode for VMs residing on NFS storage, target VMs become unresponsive for 30 seconds and removing snapshots takes a long time. 119. To determine this stun time, check Rubrik was designed to dramatically diminish the effects of virtual machine & application stunning when backing up VMware environments. For Example: If the time taken to stun a VM during snapshot create with one virtual disk is X, then, multiplying with number of VMDKs sums up the total Checkpoint_Unstun required to complete Snapshot creation After backing up a VM stored on vVol with HotAdd, snapshot removal operations stun the VM if the backup proxy server is located on a different ESXi host. On the guest VM, verify that VMware Tools are installed and up to date. vmdk snapshot that was also in . The VM is stunned to switch the virtual disk write stream from the See more To create a VM snapshot, the VM is “stunned” in order to (i) serialize device state to disk, and (ii) close the current running disk and create a snapshot point. When the snap is cleared the files are merged back into a single file and that process can cause a stun where the vm essentially pauses as VM snapshots can cause "stun moments," which are periods during which the VM is briefly paused to create the snapshot. I have the same problem wiht the time sync guest VM when i take a snapshot. If you are suspending a virtual machine, wait until the suspend operation finishes before you take a snapshot. Check for orphaned snapshots on the VM. msidnam Enthusiast Posts: 28 Liked: 2 times Joined: Fri Aug 19, 2011 3:23 pm Full Name: ME. Create a new VM and atach the disks to this new VM in their original order. 5 Update 2 hosts freeze at the *creation* of a snapshot. Worst-case scenarios improved from multi-second (5s?) to sub-second (0. The duration of the stun will depend on the number of vmdks and speed of datastore metadata operations (e. The process involved in the I/O is the VM-World process. The VM gets stunned during a snapshot. A virtual machine may also become unresponsive for a short period of time during a snapshot deletion. I read you are using Veeam. The snapshot size is small (sesparse file is 16GB big but du -h displays only 120MB being used), but during consolidation ESXi writes the whole time (10+ minutes) at 80-120MB/s to the storage array. A good blog post on stun times is here. Note that snapshot commit in VMware may take multiple stuns, so read the full log around that time. as I understand for a snapshot delete the VSS isn't used. Backing up your VMs in an application consistent manner, which is a really great idea. 0, the snapshot stun times are logged. a) Create quiesced snapshot (which what Veeam Backup does, but this is not a default option in VMware Infrastructure Client). i have not seen any ping drops during snapshots though, only vmotion Stuns will also occur when a VMware snapshot is deleted. This option can reduce any VM STUN associated with Vmware snapshot removal, but this will depend highly on the change rate across all disks that are subject to VMware snapshots. And this behavior causes massive problems in the application-layer. What is the maximum stun time for the VM during vmotion operation, snapshot creation/deletion? Is there any setting to verify this? Is there anyway to reduce the stun time of the VM? Google vmware+snapshot+stun. For VMs stored on an NFSv3 Datastore: Now, we have understood VM stun and the steps for VM snapshots, and how the delta VMDK files are merged into a single disk. At the creation point of a VM snapshot and after the backup is complete and the snapshot is committed, the VM needs to be frozen for a short period. We're currently experiencing minor stuns during both snapshot creation and removal, on all VMs. All blocks that are changed while the snapshot is active are written to the delta disk. For large deltas or slower performing storage, the stun can last long enough to When vSphere creates a snapshot of a VM on a VMFS or NFS-backed datastore, the VM is paused for a The long VM stun time reported during snapshot create was due to the time taken to search for suitable Resource Clusters (RC) to affinitize allocations to . abc. What're As @adrianyong4136 points out, Snapshots can fill a disk quickly and cause even more problems during the consolidation phase. VMs stored on vVols may experience a significant stun during the snapshot removal process after the backup session. I do not know where it can come. helper disk still exists * stun VM to halt all IO * consolidate helper disk * consolidation complete in 5. If you have a test VMS you can try without CBT backup. The sync time with Host and VMtools is uncheked and not configured in the VM. In this setup, we were Additional RDP session may drop during a long snapshot, this is expected behavior. 202. vmdk) is closed and a new delta disk is created (*-delta. Get Enterprise and backup from storage snapshots. CTK files used for CBT. But the bigger VM (~1. To quiesce the VM files, the VM must be powered on and have VMware Tools pre-installed. Might help track down your issue. After producing a snapshot of a VM disk file, requiring the VM to be stunned, a snapshot of the VM disk also an alternative way to reduce the adverse effects of the VM stun operation. VMware attempts to remove the snapshot created during a Druva job operation, and there was a snapshot present on the VM before the Druva job, snapshot stun may occur. Why is this? The reason the Virtual machine may become unresponsive is because of the stun process. If you want to have complete control I would suggest using CLI. Workaround: The PowerProtect Data Manager VMware Protection solution offers the Transparent Snapshot Data Mover (TSDM) solution, which does not require a VM snapshot to perform the backup. ) you might want to explore other backup options such as using an agent inside the guest OS instead. 0u1 to minimize the With memory snapshots, a running VM can be reverted to the state it was when the snapshot was taken. For VMs stored on an NFSv3 Datastore: Huge VM stun on snapshot merge? I've recently noticed it on some machines that are serving a web server and a MySQL database. Normally there is a performance impact during snapshot removal, which can vary significantly based on the load on the VM, especially I/O load, but the "pause" should usually only last a couple of seconds as the final "stun" freezes the system to remove the final snapshot. The smaller VMs complete backups successfully. Usually under 1s. 7u3 that was causing stun times on our MSSQL VM to randomly be over 10sec. Some of his VMware In the example above, the user is backing up the same VM at the same time using two different backup products. The performance is affected by how long the snapshot or the snapshot tree is in place. Browse to the datastore and folder where the VM is located d. This causes an issue since we have several RDP servers and VM's running on several ESXi 5. I never take snapshots with the memory as a backup. When you create a snapshot the original virtual disk (*-flat. We have an issue where the snapshot stun is significant and can stop network access for several seconds. When you get the issue again, check the corresponding VM logs files - the stun times are labeled pretty clearly there. You could run ping tests during a vsphere snapshot event at the VM in question IP address. Click to learn more about VMware snapshot stun. If you have a 10 GB snapshot that is only a day or so old, it should consolidate quickly, assuming that much of that 10 GB was bulk new data. com/virtualblocks/2020/10/29/vsphere-7-u1 When a large snapshot is removed from a VM, depending on the size of the snapshot, there could be a long stun time at the end of the consolidation process. During that time, that could go from 30 seconds to 10 minutes, some of my machines stop responding to ping, giving service and even the stun may be the equivilant of 1-2 pings in time but the actual reason for the ping drop is because the esx host sends a RARP to notify the switches that the VM has moved to a new hosts so they know where to send the network traffic. So let’s think about this. b) Keep snapshot open for long enough time before deleting it, similar to time it takes to backup the VM - to make sure it grows large (commiting large amounts of data into VMDK is what may cause some VM slowness). This stun is performed when the VM has finished current operations. Some VMs lose 3 pings. The longer you wait, the bigger the snap gets. Right click on the VM > Unregister > Ok c. Remove the snapshot. The NTP in the server is configured with the domain controler NT5DS. This happens on different VMs each time which are on different volumes and different host (we have 6 Dell R620’s). In this situation, the backup runs as a crash-consistent backup. Observe the VM during the snapshot removal. You will find a couple of tips in the topic I've referenced above, might be useful. 2 - The affected VM protection mechanism stun is by design during the VM Snapshot creation. This file is called VM_Name-Delta. For VMs stored on an NFSv3 Datastore: Is it really normal to lose some pings during snapshot of VMs? Any other thoughts, comments or recommendations are appreciated. Symptoms. A VM snapshot is a way to make point in time copy of your VM; Be careful of how long you keep a VM Stun Times. The reason the Virtual machine may become unresponsive is because of the stun process integrated with Consolidation process. Keepalived virtual IP (VIP) management and failover does not work when using VMware based snapshot stun is to long; Veeam backup degrades VMware datastore/array performance during VMware based snapshot Very active vms, active as far as storage IOPs, when a snap shot is taken the new change bits go into a different file. How big is your SQL snapshot getting? Maybe something is causing a lot of data slosh while the snapshot exists (paging? As it was mentioned, the stun from a VM snapshot with Veeam should be extremely minimal and over in a flash. The TSDM solution uses a Lightweight Delta (LWD) filter, at the Larger/more active machines are more likely to become stunned during snapshot removal, due to the relatively large amount of data that has to be merged back into the base disk. This is the first thing I would check. Snapshot Stun Issue. x or newer, the advice in this article should only be implemented if node failover issues occur due to snapshot-induced VM Guest OS I/O stun. Challenge During the snapshot creation or commit phase of a Veeam Backup or Replication job using vSphere, a primary node in a DAG cluster may lose the heartbeat long enough to cause In both cases, the snapshot consolidation takes 12 or more minutes. Thx. 8 VM Stun 9 Backup Duration In order to commit the merge I/O must be paused, during which the VM experiences stun time again. ind. These stun moments are particularly disruptive during the consolidation phase, where the snapshot data is written to disk. . Retry the backup at Remove the snapshot. Memory snapshots are ideally used when you need to save the state of running applications. 2. vm_name Failed: Unable to quiesce guest file system during snapshot creation. However, in some circumstances such as a VM with a large storage footprint, VMs consuming large amounts of storage IO, or storage that isn't fast enough, the VM stun can be disruptive. In some cases we have seen VM's unresponsive for for nearly an hour. IF the VM is ALSO And whatever else 19 other VMs are doing with those 500IOPs you'll get during snapshot consolation. This is more common and quite troublesome in situations where heavy I/O servers (like Exchange for example) live on NFS datastores. Every time when Veeam starting create backup, the VM(every time it's different VM) the VM become unavailable. 5s). ) Remove the snapshot. 5. Note: Beginning in ESXi 5. Slower than normal but it would NOT "stun" the VM when committing the snapshot and deleting it. The backup job would just hang at 95% during the removal of the snapshot. 5 or later * migrate On a powered on VM with existing snapshots if you do an Active Full which resets CBT it causes the VM to stun. For VMs stored on an NFSv3 Datastore: During the backup process NetBackup initiates a VMware level snapshot, I know these snapshots are Skip to content. vmdk). (especially during the removal stage after a snapshot when changed data had to be integrated back into Normally the stun operation is only during the final step of snapshot removal. For a highly transactional application like databases (in this case the Oracle DB), side effects can appear due to VM stun. When a large snapshot is removed from a VM, depending on the size of the snapshot, there could be a long stun time at the end of the consolidation process. Is it normal for pings to stop to a VM being snapshot or snapshot removal happening in progress. Veeam is successful in resetting CBT but vSphere (because of the existing snapshot/s) is still running a process on the VM which basically stuns/locks it. Typically, it happens so quickly you don't even notice. Rubrik will only pull data for the VMDKs that aren't excluded reducing the overall time a full or incremental backup will take thus reducing the data written to a delta Hi All, I’m running VMWare 6 with windows VMs and have noticed that when ever a snap shot is created there is a slight “pause” in the machine (about 4 pings worth). I typically see a ping or so drop on larger memory VM’s. However, it has been observed that when VMware attempts to remove the snapshot created during a Druva job operation, and there was a snapshot present on the VM before the Druva job, snapshot stun may occur. A process deleted users/non-avamar snapshot while Avamar backup was still running causing the disk specified in the work order to be invalid. As mentioned above, it's called a VM stun. Other than Veeam backups to a storage snapshot we NEVER snapshot anything outside a maintenance window due to VM stun What is typically causing the issue is VM stun during snapshot commit. vpc. No snapshot or other process should be running on the VM either. If you do face this situation, then here you go a couple of tips that might help: 1. Technically, taking a Quiesced Snapshot usually relies on tools like VMware Tools, which can interact with the operating system within Also, the VM can experience a stun, during consolidation. System Spec. During the snapshot, VMware will create a Delta VMDK file. It actually happens every time a snapshot operation is performed. They provide information on VM stun cycles duration during snapshot commit operations, basically if VM remains stunned for a few seconds, this results in network drop in guest OS. During a memory state As to using VMware snapshot technology question, then, indeed, you can observer the "usual" stun/unstun problem from VMware during VM snapshot commit operation. RE: Virtual Machine unavailable during Snapshot after all the stun process with VMware reports the stun duration as 1-3 seconds, which ties in perfectly with the amount of pings lost. Right click on the VMX file, and then Register VM. During troubleshooting we found a very slow VM snapshot deletion on NFS volumes on ESXi hosts. When When the the snapshot is created for a virtual machine, disks are closed in order to create delta disks and attach them to virtual machine. Or just create case to Veeam and they can find the cause and prove evidence, that problem caused by vmware's issue. The process is the same for both Windows and Linux. You need to configure in job settings. This has The operation will pause any operation running on the VM, including processes that might modify the VM disk during a revert operation. Also read a little on Stun times on a vm log but no real solution fixed. I summarise the details below and put them in the context of IRIS database With memory snapshots, a running VM can be reverted to the state it was when the snapshot was taken. The only way is to reset the host. pings will fail, no IO). Shutdown the VM if not already powered-off b. Make sure VM does not have any other snapshots (including hidden). Environment. For Example: If the time taken to stun a I am facing longs stun on VM very busy while backuping, during the consolidation step, something like 40s, which totally down the jobs running on the VM. Quiesced Snapshot (File System Quiescing) A Quiesced Snapshot ensures that data in memory is written to disk before the snapshot is taken, preventing inconsistencies caused by delays or incomplete data writes during backup. The issue is the snapshot grows as it sits and reconsolidation will "STUN" the VM. The longer you have VMs running on snapshots, the more the guest OSs have changed since the time you took the snapshot. Note: You can continue to use manual unmap using esxcli to The VM stun time to complete Snapshot creation operation directly correlates with number of VMDKs associated to a Virtual Machine. Do you think it's normal behaviour if a VM doesn't respond to some ping packets sent to it during a vmware snapshot creation or deletion? Advertisement Coins. During this stun process the VM its OS cannot execute any operations and is essentially in a "stuck" state (e. When a backup operation is performed using HotAdd mode, virtual machines (VMs) that reside on NFS storage might stop responding during a snapshot removal operation. After removing all the snapshots using the snapshot manager for that particualar VM As you know, snapshots affect the performance of virtual machines (VMs) in your VMware environment. vmware. If you want to check Remove the snapshot. Arctera. A VM snapshot is a way to make point in time copy of your VM; Be careful of how long you keep a ESXi Host MGMT IP vMotion IP vxyzcldesx0101a. VM loses connection during This stun is performed when the VM has finished current operations. Some VMs even have a freeze period of 1 minute! Network connection is lost during freeze. Sometimes the backup snapshot close without issues, sometimes they stun the vm indefinitely and lock up the host. The main thing to note here is that I cloned the root VMDK, not the vm-00002. Now the stuns are usually pretty quick in human terms (sub-second), but in machine terms they're pretty long, several hundred You can take a snapshot when a virtual machine is powered on, powered off, or suspended. Some data protection solutions are able to provide full application-aware quiescence during a snapshot. That's a pretty large topic to read, so as a short summary - VM stun can happen during snapshot commit operation. When snapshots consolidate, they halve repeatedly until the last one where it pauses the VM stuns" it briefly. Some of his VMware When taking snapshots of VMs, the quiescing option provides additional control to ensure consistency of the VM’s data over and above the regular crash consistent snapshot - additional work is required to script or configure those controls and once in place these can be used by VMware Cloud DR when creating Recovery Points for Disaster it is not about the size of the snapshot, but the age. https://blogs. 544z| vcpu-0 | checkpoint_Unstun: vm stopped for 403475568 us As in thread title pretty much. 0. On a side note, I've found that additional vmdk drives increase stun times considerably. No heavy loads, so no long stuns - total stun periods are about 2-4 seconds per VM during backup, and the stun is not continious. VMDK increasing the I/O of this operation. both vMo and SVMo are impacted by how much To workaround this issue, disable the automatic unmap processing on all the hosts sharing the volume. But, a 10 GB snapshot that is a month or more old, on a system that has a lot of little changes over time will likely take a lot longer. A very intersting thread. All the other VMs are running fine, though. At first I thought the system was BSOD'ing, but I have disabled "Automatic restart on blue screen" and the system doesn't halt at all -- it's almost like something is rebooting it. g. Restarting a machine during snapshot removal. rchew wrote:It always happens right after the snapshot removal. When you create a memory snapshot, the snapshot captures the state of the virtual machine memory and the virtual machine power settings. 201. Probably not exactly stun but the state of the VM is killed and started from the snapshot so there will be a moment in time where the VM appears to be stunned right? During the snapshot removal component of a Druva backup the source virtual machine loses connectivity temporarily. From a VMware KB: A snapshot removal can stop a virtual machine for long time. The freeze periode depends on the VM. So you want there to be as little as possible to do. 7. During this stun, the guest OS is frozen, and so when it comes back, the system clock is behind. Example. The SES stores the bitmaps that correspond to the data in the VM gets unresponsive when removing a snapshot – Snapshot consolidation takes 30 minutes and longer A customer of us informed us about the following situation he ran into. The “stun” is typically a short pause (usually only a few seconds or less); the VM is unresponsive (“lost ping”) while the very last bits of the snapshot file are being committed. log file for the VM for a message similar to the one below: YYYY-MM-DD TIME. 996 F5949B90 verbose 'vm: We had 2 scripts for CBT snapshot and without CBT. 8 posts • Page 1 of 1. shut the VM down completely then snapshot it. If this is a high-I/O VM (busy SQL server, Exchange, etc. Druva can back up a VM that has snapshots present. is dynamically created during snapshot creation and is deleted when the snapshot is retired. Also, the b. Clone each disk using vmkfstools by using the last snapshot file as input. How does Veeam ensure efficient use of delta files during backup operations? Typically, the problem of frozen VM during snapshot commit process is related to VMware rather than Veeam side. This happens after veeam is done backing up and has to merge the snapshot file. Virtual machine experiences very long stun time during snapshot creation initiated from backup software. If you take multiple snapshots you are referring to the last delta file of the last snapshot not the original VMDK thus increasing I/O. 41 VM gets unresponsive when removing a snapshot – Snapshot consolidation takes 30 minutes and longer A customer of us informed us about the following situation he ran into. meaning that upon snapshot creation there will be a little bit of a stun, and then on snapshot deletion there'll be even more of a stun as all the changes are recommitted. Minimizing the Impact of VMware Snapshots During Backups. cite eefo iybp umyiwz ikht xogu touaof lipqit jqp vveiawl