Implementation of RAM-based Cache at Write-back Mode Using Virtual-NAS for DAS-based Storage on VMware Platform

Storage was one of the crucial components that have a big impact on overall system performance, especially in a virtualization environment. The application of cache as storage performance accelerator was an option especially for small scale environments with limited resources and the usage of DAS-based storage scenarios (Direct-Attached Storage). Maximum performance obtained when the cache function was applied to both read and write operations (at write-back mode), but there was a limitation for RAM-based cache implementation on the DAS-based storage scenario with VMware-based platform which currently only supports write- through mode (acceleration was only for read operations). This paper tried to propose an alternative solution using a virtual NAS approach to apply RAM-based cache that runs in writeback mode at VMware platform on DAS-based storage scenario. Performance test performed using the workload simulation tool for single-cache and multi-cache implementation scenarios. The test results showed a significant performance improvement for read and write operations compared to baseline (without cache condition) within the scope of the workload simulation being performed. A single cache implementation scenario, the improvement range for read operation was between 27.71x - 98.02x, while write operation was between 21.94x - 63.21x better than baseline. In a multi-cache implementation scenario, the range of performance improvement for reading operations was between 110.37x - 431.43x, whereas for write operations it was in the range of 23.14x - 391.76x better than baseline.