datastore usage on disk alarm clearing .snapshot

When you perform VMware disk consolidation, data from delta disks is merged to a single disk, and no redundant data is left on the datastore where this VM’s files are located. When the chain of snapshots and related virtual disk files becomes large, performance degrades. As a result, redundant data is present in the virtual machine storage because each delta disk contains all changes made as compared to the previous delta disk state, and the parent disk remains unchanged. When you take a snapshot, delta disks are created and changes are written to the appropriate delta disk (the latest delta disk by default, until one of the previous snapshots is selected to restore the virtual machine). You can initiate disk consolidation on demand to avoid performance degradation and other issues. Virtual disk consolidation is the process of merging virtual disk files created after taking VM snapshots. Control snapshot space allocation to keep your NAS functional.What is good about the way QNAP does snapshots?.How do QNAP’s block-level snapshots work?.DISCOVER SOLUTION What Is VMware Disk Consolidation? In short snapshots are versioning, or the ability to undo a change. If you take a snapshot every hour, for example, then all your files or folders can be reverted back to the state they were at the time of any of your snapshots. So, if you get a virus, then you can just revert your files, folders, or whole volume to the state it was before you got the virus How is this different than a backup?Ī backup is a complete copy of your data. So, if you have 5TB of data each copy will take up an additional 5TB of space. If you make a backup every 1 hour, then after just 10 hours, your backups would take 50TB of space. For this reason, it is not common to save many versions of your backups and backups are not good for versioning. Snapshots are great for versioning because they are not backups and they can have many versions without taking up much space. How do QNAP’s block-level snapshots work? A snapshot only needs to save enough information to undo a change and that makes it take less space than a backup. When you take a snapshot, the metadata recording where each block of data is stored is copied to the snapshot. This takes very little space and the snapshot is created very quickly. From then on, any time you change a block of data, that block is written to a designated snapshot space. The current metadata is updated to reflect the change as well. This procedure is called “Redirect on write”.īecause your snapshot has the metadata, it can recognize what blocks of data have been added or changed since the creation of the snapshot. If you revert to one of your snapshots, every block of data that was added or changed since the snapshot was taken is removed from where it is saved in the snapshot. Then every block of data is as it was at the time the snapshot was taken. And since your files are made up of blocks of data, every file is now as it was when the snapshot was taken. What is good about the way QNAP does snapshots? Easy to navigate interface: This allows you to undo changes to your files, folders, and even volume, or to bring back files you have deleted accidentally. Just click on what snapshot you want to load, and then you can revert the whole volume or select a specific file or folder to restore.

Datastore usage on disk alarm clearing .snapshot