New release of Virsto One!
Posted Monday, May 10, 2010 in News 0 comments
Six weeks after our initial release of Virsto One we welcome version 1.1. We would not call it 1.1 unless we responded to customer feedback and introduced new features, along with some bug fixes.
I would like to highlight some changes to tracking and disk space reporting.
If you are reading this post than you may already be aware that Virsto One supports thinly provisioned storage and block sharing between storage objects. If not, I suggest reading our architectural white paper.
The physical data blocks in a virtual disk may be highly shared. For example after creating a clone with Virsto One, the total number of physical blocks allocated does not change, but the logical space shown is twice the original size, because now we have two objects (the parent and clone) of equal size. Only after writing to the clone are private blocks allocated, and then the number of physical blocks allocated will increase accordingly.
This seems rather trivial and conceptually it is. However, once you create a large number of virtual disks, clones, and clones of clones – where each of these objects has a number of private allocations – the resulting space allocation picture can be rather complex. The good news is this complexity is what Virsto One keeps track of, so users needn't ever be concerned with it.
Because of Virsto's scalable block sharing, there is usually a difference – often quite large – between physical space consumption and logical space used. Allocating a much smaller amount of physical capacity while presenting a vastly larger amount of logical disk space is one of Virsto One's key value propositions. With Virsto One, you'll buy a good deal less storage hardware than you'd otherwise need.
How much disk space is taken by a particular vDisk?
The answer to this seemingly simple query is, "It depends".
It depends on how much sharing of physical data blocks there is between that vDisk and other objects. The true amount could be as little as zero, and as large as the logical size of the vDisk.
Note that the size of the vDisk as reported to any interrogation will be the logical size of the disk, even if the physical space is zero. As far as any system software is concerned, Virsto One vDisks with their highly shared data blocks behave as if there was no sharing at all. Making Virsto vDisks behave exactly like standard VHDs – even though they are much more space efficient and higher performance – is a fundamental design goal of our software.
Physical disk space reporting in Virsto One is fundamentally a system wide concept. Deleting a virtual disk may or may not lead to freeing up of a significant amount of space. By the way, freeing up of space happens as a background operation so that garbage collection doesn't impact online disk performance.
Space reporting improvements in Virsto One v1.1
Our initial release of Virsto One did not do a good job of showing disk space allocation dynamics. In version 1.1 we changed the way vDisk deletion is presented. Now, deleting a vDisk removes it from vDisk name space and its disk blocks are placed into pool called "pending deletion". We also introduced a system wide gauge which shows three essential parameters of physical disk space space:
- Allocated space in use
- Free space available for immediate allocation
- Pending deletion
We present this dynamic gauge in our Hyper-V Mananager MMC snap-in. This information is also available via WMI and PowerShell to simplify integration with your favorite management framework, including homegrown scripts.
If you still have not tried Virsto One, there is no better time than the present.
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