Virtualization technologies and performance needs have increased the demand in mid-range storage solutions for the last 2 years in Turkey's market. Since performance needs are satisfied easily with tiering features most of the CIOs prefer to invest in mid-range storage solutions although a standard entry-level storage would easily handle their current I/O traffic.
At this point, in nearly every Project HP 3PAR, IBM V7000 and EMC VNX 5000 series products are entered into rivalry with each other. Because of the controller and raid architecture which requires minimum 8 SSDs to build an array for tiering, HP 3PAR solutions fail to beat its rivals in total price perspective. With the firmware version 3.2.1, HP announced a new feature called Adaptive Flash Cache. This new feature brings the ability to make an additional controller cache with minimum 4 SSD disks without the need to build an SSD array. This additional controller cache is used in RAID1 architecture which means all cached data is mirrored. Controller moves the hot chunklets to the SSD cache area automatically and this reduces the latency for random read operations which is the typical I/O behavior for most of mixed virtualization environments. Having a big level-2 cache size brings the probability to cache hit ratio for the storage and accordingly overall latency decreases dramatically while IOPS value increases.
This is the basic definition of this feature so in our first implementation, we want to challenge the product to see whether it is as good as it says. We made an implementation in one of our clients which is the leading entertainment and leisure company in Turkey. After everything was set we created an I/O traffic with IOmeter on one of the virtual machines and track the changes on 3PAR management console. The results were impressive.
After a short learning period, IOPS value increased from average 3.000 IOPS to 22.500 IOPS while latency decreased from 6 ms to <1 ms. This stress test was made with random I/O characteristics which we wanted to see. When we repeated the same test with sequential I/O characteristics IOPS values was around 8.000 IOPS.
As a conclusion, Adaptive Flash Cache feature works just fine and bring impressive performance improvements for random read environments. Data I/O characteristic will also define the result but in our perspective this feature fits perfectly for the great majority of the virtualization environments. Adaptive Flash Cache feature comes with the basic OS license and adaptive optimization or dynamic optimization licenses do not needed. This feature gives a leverage for HP 3PAR Systems against its rivals.