There are many I/O caching solutions that employ Solid State Drives (SSDs) to bridge the performance gap between the CPUs and the virtual infrastructure’s I/O sub-system. However Symantec Storage Foundation’s SmartIO along with Dynamic Multi-pathing’s SmartPool employs a ‘SMART’ way for achieving this.
In virtual environments, the virtual infrastructure administrator gets requests to provision virtual machines specifying the amount of physical resources – CPU power, memory size and storage space, that are required for the virtual machine to operate. The storage space requirement is typically met by assigning one or more virtual storage devices depending on the storage’s characteristics such as performance, flexibility etc.
Once the resources are provisioned, it’s left to the system administrator to choose how to assign these to various applications that they plan to run on the virtual machine and the virtual infrastructure administrator has no visibility into it. Similarly when the storage space is spread across multiple devices as well; the virtual infrastructure administrator has no visibility into how the applications in the virtual machines would use these storage devices, which require caching and which do not. Even within a single storage device, when a file system or database is created on it, there is no visibility from outside the virtual machine into how the device is partitioned among various file system or database objects. There is no distinction between the portions that store important data and portions that store less important stuff.
A SSD on the physical machine is a precious resource. Therefore a judicious use of it needs to be made to store only the important stuff. The visibility of the important stuff can be made only from within the virtual machine and not outside. Besides one caching solution does not fit all and needs to be tailored according to the application running in the virtual machine. Therefore it’s best to provision the SSD as a separate resource at the virtual machine’s disposal along with CPU, memory and storage.
Directly mapping an SSD to a particular virtual machine robs the advantage of sharing it with other virtual machines and also the ability to move the virtual machine across physical frames. Also creating a datastore on the SSD to share it among multiple virtual machines does not provide the required performance advantage.
Therefore Veritas employs a ‘smart’ solution where in
Besides the obvious advantage of being closer to the application, SmartIO caching solution provides other significant features that go a long way in ensuring better application performance
So you do see that lot on thought and years of experience of providing infrastructure for running enterprise class applications has gone into developing this solution. I am sure after reading this most of you would agree that this is the ‘Smart’ way to do I/O caching and achieve application performance gains.
Looking forward to your comments and experiences with this solution. Your feedback would help in further fine tuning the offering…
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